diff --git a/.dockerignore b/.dockerignore index 25a1c8e..fadf35b 100644 --- a/.dockerignore +++ b/.dockerignore @@ -1,4 +1,11 @@ * !*.py +!*.txt +!*.html +!*.sh !requirements.txt !SOURCE_DOCUMENTS +!static +!websocket + + diff --git a/.flake8 b/.flake8 deleted file mode 100644 index 3a87b26..0000000 --- a/.flake8 +++ /dev/null @@ -1,4 +0,0 @@ -[flake8] -exclude = docs -max-line-length = 119 -extend-ignore = E203 diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..a6344aa --- /dev/null +++ b/.gitattributes @@ -0,0 +1,35 @@ +*.7z filter=lfs diff=lfs merge=lfs -text +*.arrow filter=lfs diff=lfs merge=lfs -text +*.bin filter=lfs diff=lfs merge=lfs -text +*.bz2 filter=lfs diff=lfs merge=lfs -text +*.ckpt filter=lfs diff=lfs merge=lfs -text +*.ftz filter=lfs diff=lfs merge=lfs -text +*.gz filter=lfs diff=lfs merge=lfs -text +*.h5 filter=lfs diff=lfs merge=lfs -text +*.joblib filter=lfs diff=lfs merge=lfs -text +*.lfs.* filter=lfs diff=lfs merge=lfs -text +*.mlmodel filter=lfs diff=lfs merge=lfs -text +*.model filter=lfs diff=lfs merge=lfs -text +*.msgpack filter=lfs diff=lfs merge=lfs -text +*.npy filter=lfs diff=lfs merge=lfs -text +*.npz filter=lfs diff=lfs merge=lfs -text +*.onnx filter=lfs diff=lfs merge=lfs -text +*.ot filter=lfs diff=lfs merge=lfs -text +*.parquet filter=lfs diff=lfs merge=lfs -text +*.pb filter=lfs diff=lfs merge=lfs -text +*.pickle filter=lfs diff=lfs merge=lfs -text +*.pkl filter=lfs diff=lfs merge=lfs -text +*.pt filter=lfs diff=lfs merge=lfs -text +*.pth filter=lfs diff=lfs merge=lfs -text +*.rar filter=lfs diff=lfs merge=lfs -text +*.safetensors filter=lfs diff=lfs merge=lfs -text +saved_model/**/* filter=lfs diff=lfs merge=lfs -text +*.tar.* filter=lfs diff=lfs merge=lfs -text +*.tar filter=lfs diff=lfs merge=lfs -text +*.tflite filter=lfs diff=lfs merge=lfs -text +*.tgz filter=lfs diff=lfs merge=lfs -text +*.wasm filter=lfs diff=lfs merge=lfs -text +*.xz filter=lfs diff=lfs merge=lfs -text +*.zip filter=lfs diff=lfs merge=lfs -text +*.zst filter=lfs diff=lfs merge=lfs -text +*tfevents* filter=lfs diff=lfs merge=lfs -text diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml deleted file mode 100644 index 5b565d9..0000000 --- a/.pre-commit-config.yaml +++ /dev/null @@ -1,49 +0,0 @@ -default_stages: [commit] - -repos: - - repo: https://github.com/pre-commit/pre-commit-hooks - rev: v4.4.0 - hooks: - - id: trailing-whitespace - - id: end-of-file-fixer - - id: check-json - - id: check-toml - - id: check-xml - - id: check-yaml - - id: debug-statements - - id: check-builtin-literals - - id: check-case-conflict - - id: detect-private-key - - - repo: https://github.com/pre-commit/mirrors-prettier - rev: "v3.0.0-alpha.9-for-vscode" - hooks: - - id: prettier - args: ["--tab-width", "2"] - - - repo: https://github.com/asottile/pyupgrade - rev: v3.4.0 - hooks: - - id: pyupgrade - args: [--py311-plus] - exclude: hooks/ - - - repo: https://github.com/psf/black - rev: 23.3.0 - hooks: - - id: black - - - repo: https://github.com/PyCQA/isort - rev: 5.12.0 - hooks: - - id: isort - - - repo: https://github.com/PyCQA/flake8 - rev: 6.0.0 - hooks: - - id: flake8 - -ci: - autoupdate_schedule: weekly - skip: [] - submodules: false diff --git a/Dockerfile b/Dockerfile index f651715..f1e1a76 100644 --- a/Dockerfile +++ b/Dockerfile @@ -1,21 +1,37 @@ # syntax=docker/dockerfile:1 # Build as `docker build . -t localgpt`, requires BuildKit. # Run as `docker run -it --mount src="$HOME/.cache",target=/root/.cache,type=bind --gpus=all localgpt`, requires Nvidia container toolkit. +FROM nvidia/cuda:12.1.1-devel-ubuntu22.04 + +RUN apt-get update && apt-get upgrade -y \ + && apt-get install -y git build-essential libpq-dev gcc \ + wget ocl-icd-opencl-dev opencl-headers clinfo \ + libclblast-dev libopenblas-dev software-properties-common \ + g++-11 make python3 python-is-python3 pip redis \ + && mkdir -p /etc/OpenCL/vendors && echo "libnvidia-opencl.so.1" > /etc/OpenCL/vendors/nvidia.icd -FROM nvidia/cuda:11.7.1-runtime-ubuntu22.04 -RUN apt-get update && apt-get install -y software-properties-common -RUN apt-get install -y g++-11 make python3 python-is-python3 pip -# only copy what's needed at every step to optimize layer cache -COPY ./requirements.txt . -# use BuildKit cache mount to drastically reduce redownloading from pip on repeated builds -RUN --mount=type=cache,target=/root/.cache CMAKE_ARGS="-DLLAMA_CUBLAS=on" FORCE_CMAKE=1 pip install --timeout 100 -r requirements.txt llama-cpp-python==0.1.83 -COPY SOURCE_DOCUMENTS ./SOURCE_DOCUMENTS -COPY ingest.py constants.py ./ -# Docker BuildKit does not support GPU during *docker build* time right now, only during *docker run*. -# See . -# If this changes in the future you can `docker build --build-arg device_type=cuda . -t localgpt` (+GPU argument to be determined). -ARG device_type=cpu -RUN --mount=type=cache,target=/root/.cache python ingest.py --device_type $device_type COPY . . -ENV device_type=cuda -CMD python run_localGPT.py --device_type $device_type + +# setting build related env vars +ENV CUDA_DOCKER_ARCH=all +ENV LLAMA_CUBLAS=1 + +# Install depencencies +RUN python -m pip install --upgrade pip pytest cmake \ + scikit-build setuptools fastapi uvicorn sse-starlette \ + pydantic-settings starlette-context gradio huggingface_hub hf_transfer + +RUN CMAKE_ARGS="-DLLAMA_CUBLAS=on" pip install llama-cpp-python +RUN CMAKE_ARGS="-DLLAMA_CUBLAS=on" FORCE_CMAKE=1 PIP_ROOT_USER_ACTION=ignore pip install --ignore-installed --timeout 100 -r requirements.txt +RUN pip install uvicorn + +RUN useradd -m -u 1000 user +USER user + +WORKDIR $HOME/app + +COPY --chown=user . $HOME/app + +RUN chmod +x ./run.sh + +CMD ["sh", "run.sh"] diff --git a/README.md b/README.md index 57d6538..7acef59 100644 --- a/README.md +++ b/README.md @@ -1,326 +1,8 @@ -# LocalGPT: Secure, Local Conversations with Your Documents 🌐 - -**LocalGPT** is an open-source initiative that allows you to converse with your documents without compromising your privacy. With everything running locally, you can be assured that no data ever leaves your computer. Dive into the world of secure, local document interactions with LocalGPT. - -## Features 🌟 -- **Utmost Privacy**: Your data remains on your computer, ensuring 100% security. -- **Versatile Model Support**: Seamlessly integrate a variety of open-source models, including HF, GPTQ, GGML, and GGUF. -- **Diverse Embeddings**: Choose from a range of open-source embeddings. -- **Reuse Your LLM**: Once downloaded, reuse your LLM without the need for repeated downloads. -- **Chat History**: Remembers your previous conversations (in a session). -- **API**: LocalGPT has an API that you can use for building RAG Applications. -- **Graphical Interface**: LocalGPT comes with two GUIs, one uses the API and the other is standalone (based on streamlit). -- **GPU, CPU & MPS Support**: Supports multiple platforms out of the box, Chat with your data using `CUDA`, `CPU` or `MPS` and more! - -## Dive Deeper with Our Videos đŸŽ„ -- [Detailed code-walkthrough](https://youtu.be/MlyoObdIHyo) -- [Llama-2 with LocalGPT](https://youtu.be/lbFmceo4D5E) -- [Adding Chat History](https://youtu.be/d7otIM_MCZs) -- [LocalGPT - Updated (09/17/2023)](https://youtu.be/G_prHSKX9d4) - -## Technical Details đŸ› ïž -By selecting the right local models and the power of `LangChain` you can run the entire RAG pipeline locally, without any data leaving your environment, and with reasonable performance. - -- `ingest.py` uses `LangChain` tools to parse the document and create embeddings locally using `InstructorEmbeddings`. It then stores the result in a local vector database using `Chroma` vector store. -- `run_localGPT.py` uses a local LLM to understand questions and create answers. The context for the answers is extracted from the local vector store using a similarity search to locate the right piece of context from the docs. -- You can replace this local LLM with any other LLM from the HuggingFace. Make sure whatever LLM you select is in the HF format. - -This project was inspired by the original [privateGPT](https://github.com/imartinez/privateGPT). - -## Built Using đŸ§© -- [LangChain](https://github.com/hwchase17/langchain) -- [HuggingFace LLMs](https://huggingface.co/models) -- [InstructorEmbeddings](https://instructor-embedding.github.io/) -- [LLAMACPP](https://github.com/abetlen/llama-cpp-python) -- [ChromaDB](https://www.trychroma.com/) -- [Streamlit](https://streamlit.io/) - -# Environment Setup 🌍 - -1. đŸ“„ Clone the repo using git: - -```shell -git clone https://github.com/PromtEngineer/localGPT.git -``` - -2. 🐍 Install [conda](https://www.anaconda.com/download) for virtual environment management. Create and activate a new virtual environment. - -```shell -conda create -n localGPT python=3.10.0 -conda activate localGPT -``` - -3. đŸ› ïž Install the dependencies using pip - -To set up your environment to run the code, first install all requirements: - -```shell -pip install -r requirements.txt -``` - -***Installing LLAMA-CPP :*** - -LocalGPT uses [LlamaCpp-Python](https://github.com/abetlen/llama-cpp-python) for GGML (you will need llama-cpp-python <=0.1.76) and GGUF (llama-cpp-python >=0.1.83) models. - - -If you want to use BLAS or Metal with [llama-cpp](https://github.com/abetlen/llama-cpp-python#installation-with-openblas--cublas--clblast--metal) you can set appropriate flags: - -For `NVIDIA` GPUs support, use `cuBLAS` - -```shell -# Example: cuBLAS -CMAKE_ARGS="-DLLAMA_CUBLAS=on" FORCE_CMAKE=1 pip install llama-cpp-python==0.1.83 --no-cache-dir -``` - -For Apple Metal (`M1/M2`) support, use - -```shell -# Example: METAL -CMAKE_ARGS="-DLLAMA_METAL=on" FORCE_CMAKE=1 pip install llama-cpp-python==0.1.83 --no-cache-dir -``` -For more details, please refer to [llama-cpp](https://github.com/abetlen/llama-cpp-python#installation-with-openblas--cublas--clblast--metal) - -## Docker 🐳 - -Installing the required packages for GPU inference on NVIDIA GPUs, like gcc 11 and CUDA 11, may cause conflicts with other packages in your system. -As an alternative to Conda, you can use Docker with the provided Dockerfile. -It includes CUDA, your system just needs Docker, BuildKit, your NVIDIA GPU driver and the NVIDIA container toolkit. -Build as `docker build . -t localgpt`, requires BuildKit. -Docker BuildKit does not support GPU during *docker build* time right now, only during *docker run*. -Run as `docker run -it --mount src="$HOME/.cache",target=/root/.cache,type=bind --gpus=all localgpt`. - -## Test dataset - -For testing, this repository comes with [Constitution of USA](https://constitutioncenter.org/media/files/constitution.pdf) as an example file to use. - -## Ingesting your OWN Data. -Put you files in the `SOURCE_DOCUMENTS` folder. You can put multiple folders within the `SOURCE_DOCUMENTS` folder and the code will recursively read your files. - -### Support file formats: -LocalGPT currently supports the following file formats. LocalGPT uses `LangChain` for loading these file formats. The code in `constants.py` uses a `DOCUMENT_MAP` dictionary to map a file format to the corresponding loader. In order to add support for another file format, simply add this dictionary with the file format and the corresponding loader from [LangChain](https://python.langchain.com/docs/modules/data_connection/document_loaders/). - -```shell -DOCUMENT_MAP = { - ".txt": TextLoader, - ".md": TextLoader, - ".py": TextLoader, - ".pdf": PDFMinerLoader, - ".csv": CSVLoader, - ".xls": UnstructuredExcelLoader, - ".xlsx": UnstructuredExcelLoader, - ".docx": Docx2txtLoader, - ".doc": Docx2txtLoader, -} -``` - -### Ingest - -Run the following command to ingest all the data. - -If you have `cuda` setup on your system. - -```shell -python ingest.py -``` -You will see an output like this: -Screenshot 2023-09-14 at 3 36 27 PM - - -Use the device type argument to specify a given device. -To run on `cpu` - -```sh -python ingest.py --device_type cpu -``` - -To run on `M1/M2` - -```sh -python ingest.py --device_type mps -``` - -Use help for a full list of supported devices. - -```sh -python ingest.py --help -``` - -This will create a new folder called `DB` and use it for the newly created vector store. You can ingest as many documents as you want, and all will be accumulated in the local embeddings database. -If you want to start from an empty database, delete the `DB` and reingest your documents. - -Note: When you run this for the first time, it will need internet access to download the embedding model (default: `Instructor Embedding`). In the subsequent runs, no data will leave your local environment and you can ingest data without internet connection. - -## Ask questions to your documents, locally! - -In order to chat with your documents, run the following command (by default, it will run on `cuda`). - -```shell -python run_localGPT.py -``` -You can also specify the device type just like `ingest.py` - -```shell -python run_localGPT.py --device_type mps # to run on Apple silicon -``` - -This will load the ingested vector store and embedding model. You will be presented with a prompt: - -```shell -> Enter a query: -``` - -After typing your question, hit enter. LocalGPT will take some time based on your hardware. You will get a response like this below. -Screenshot 2023-09-14 at 3 33 19 PM - -Once the answer is generated, you can then ask another question without re-running the script, just wait for the prompt again. - - -***Note:*** When you run this for the first time, it will need internet connection to download the LLM (default: `TheBloke/Llama-2-7b-Chat-GGUF`). After that you can turn off your internet connection, and the script inference would still work. No data gets out of your local environment. - -Type `exit` to finish the script. - -### Extra Options with run_localGPT.py - -You can use the `--show_sources` flag with `run_localGPT.py` to show which chunks were retrieved by the embedding model. By default, it will show 4 different sources/chunks. You can change the number of sources/chunks - -```shell -python run_localGPT.py --show_sources -``` - -Another option is to enable chat history. ***Note***: This is disabled by default and can be enabled by using the `--use_history` flag. The context window is limited so keep in mind enabling history will use it and might overflow. - -```shell -python run_localGPT.py --use_history -``` - - -# Run the Graphical User Interface - -1. Open `constants.py` in an editor of your choice and depending on choice add the LLM you want to use. By default, the following model will be used: - - ```shell - MODEL_ID = "TheBloke/Llama-2-7b-Chat-GGUF" - MODEL_BASENAME = "llama-2-7b-chat.Q4_K_M.gguf" - ``` - -3. Open up a terminal and activate your python environment that contains the dependencies installed from requirements.txt. - -4. Navigate to the `/LOCALGPT` directory. - -5. Run the following command `python run_localGPT_API.py`. The API should being to run. - -6. Wait until everything has loaded in. You should see something like `INFO:werkzeug:Press CTRL+C to quit`. - -7. Open up a second terminal and activate the same python environment. - -8. Navigate to the `/LOCALGPT/localGPTUI` directory. - -9. Run the command `python localGPTUI.py`. - -10. Open up a web browser and go the address `http://localhost:5111/`. - - -# How to select different LLM models? - -To change the models you will need to set both `MODEL_ID` and `MODEL_BASENAME`. - -1. Open up `constants.py` in the editor of your choice. -2. Change the `MODEL_ID` and `MODEL_BASENAME`. If you are using a quantized model (`GGML`, `GPTQ`, `GGUF`), you will need to provide `MODEL_BASENAME`. For unquantized models, set `MODEL_BASENAME` to `NONE` -5. There are a number of example models from HuggingFace that have already been tested to be run with the original trained model (ending with HF or have a .bin in its "Files and versions"), and quantized models (ending with GPTQ or have a .no-act-order or .safetensors in its "Files and versions"). -6. For models that end with HF or have a .bin inside its "Files and versions" on its HuggingFace page. - - - Make sure you have a `MODEL_ID` selected. For example -> `MODEL_ID = "TheBloke/guanaco-7B-HF"` - - Go to the [HuggingFace Repo](https://huggingface.co/TheBloke/guanaco-7B-HF) - -7. For models that contain GPTQ in its name and or have a .no-act-order or .safetensors extension inside its "Files and versions on its HuggingFace page. - - - Make sure you have a `MODEL_ID` selected. For example -> model_id = `"TheBloke/wizardLM-7B-GPTQ"` - - Got to the corresponding [HuggingFace Repo](https://huggingface.co/TheBloke/wizardLM-7B-GPTQ) and select "Files and versions". - - Pick one of the model names and set it as `MODEL_BASENAME`. For example -> `MODEL_BASENAME = "wizardLM-7B-GPTQ-4bit.compat.no-act-order.safetensors"` - -8. Follow the same steps for `GGUF` and `GGML` models. - -# GPU and VRAM Requirements - -Below is the VRAM requirement for different models depending on their size (Billions of parameters). The estimates in the table does not include VRAM used by the Embedding models - which use an additional 2GB-7GB of VRAM depending on the model. - -| Mode Size (B) | float32 | float16 | GPTQ 8bit | GPTQ 4bit | -| ------- | --------- | --------- | -------------- | ------------------ | -| 7B | 28 GB | 14 GB | 7 GB - 9 GB | 3.5 GB - 5 GB | -| 13B | 52 GB | 26 GB | 13 GB - 15 GB | 6.5 GB - 8 GB | -| 32B | 130 GB | 65 GB | 32.5 GB - 35 GB| 16.25 GB - 19 GB | -| 65B | 260.8 GB | 130.4 GB | 65.2 GB - 67 GB| 32.6 GB - 35 GB | - - -# System Requirements - -## Python Version - -To use this software, you must have Python 3.10 or later installed. Earlier versions of Python will not compile. - -## C++ Compiler - -If you encounter an error while building a wheel during the `pip install` process, you may need to install a C++ compiler on your computer. - -### For Windows 10/11 - -To install a C++ compiler on Windows 10/11, follow these steps: - -1. Install Visual Studio 2022. -2. Make sure the following components are selected: - - Universal Windows Platform development - - C++ CMake tools for Windows -3. Download the MinGW installer from the [MinGW website](https://sourceforge.net/projects/mingw/). -4. Run the installer and select the "gcc" component. - -### NVIDIA Driver's Issues: - -Follow this [page](https://linuxconfig.org/how-to-install-the-nvidia-drivers-on-ubuntu-22-04) to install NVIDIA Drivers. - -## Star History - -[![Star History Chart](https://api.star-history.com/svg?repos=PromtEngineer/localGPT&type=Date)](https://star-history.com/#PromtEngineer/localGPT&Date) - -# Disclaimer - -This is a test project to validate the feasibility of a fully local solution for question answering using LLMs and Vector embeddings. It is not production ready, and it is not meant to be used in production. Vicuna-7B is based on the Llama model so that has the original Llama license. - -# Common Errors - - - [Torch not compatible with CUDA enabled](https://github.com/pytorch/pytorch/issues/30664) - - - Get CUDA version - ```shell - nvcc --version - ``` - ```shell - nvidia-smi - ``` - - Try installing PyTorch depending on your CUDA version - ```shell - conda install -c pytorch torchvision cudatoolkit=10.1 pytorch - ``` - - If it doesn't work, try reinstalling - ```shell - pip uninstall torch - pip cache purge - pip install torch -f https://download.pytorch.org/whl/torch_stable.html - ``` - -- [ERROR: pip's dependency resolver does not currently take into account all the packages that are installed](https://stackoverflow.com/questions/72672196/error-pips-dependency-resolver-does-not-currently-take-into-account-all-the-pa/76604141#76604141) - ```shell - pip install h5py - pip install typing-extensions - pip install wheel - ``` -- [Failed to import transformers](https://github.com/huggingface/transformers/issues/11262) - - Try re-install - ```shell - conda uninstall tokenizers, transformers - pip install transformers - ``` -- [ERROR: "If reserved but unallocated memory is large try setting max_split_size_mb to avoid fragmentation..." ](https://pytorch.org/docs/stable/notes/cuda.html#memory-management) - ```shell - export PYTORCH_NO_CUDA_MEMORY_CACHING=1 - ``` - +--- +license: mit +title: katara +sdk: docker +emoji: 🚀 +colorFrom: yellow +colorTo: yellow +--- diff --git a/SOURCE_DOCUMENTS/dataset.txt b/SOURCE_DOCUMENTS/dataset.txt index 42acafe..870b8f9 100644 --- a/SOURCE_DOCUMENTS/dataset.txt +++ b/SOURCE_DOCUMENTS/dataset.txt @@ -1 +1,26474 @@ -These ensemble experiments underline the importance of both spring sea ice and summer atmospheric forcing to August SIC. In summary, we find that: Spring ice conditions were mostly responsible for the summer SIC anomaly through the end of July, while the atmosphere was mainly responsible for driving SIC to a record low during August. Partitioning the impact of 2020 spring initial sea ice conditions vs. summer atmospheric forcing on the sea ice anomaly at the time of the WS sea ice minimum on August 14 (see “Methods”) attributes ~20% to the initial conditions while ~80% is the due to the atmospheric forcing. Assuming that the increasing presence over the past 40 years of thin ice and open water at the beginning of the melt season (Fig. 5c) is primarily driven by climate change and that the summer atmospheric conditions were due to internal variability, the above 20/80 partitioning provides an approximate measure of the contributions of climate change and internal variability to the 2020 event (see further discussion in “Methods”). Is this 20% climate change signal significant or not? Extreme local events such as storms, heat waves, or floods are almost always dominated by dynamics driven by internal climate variability15. For example, flooding in New York City in response to Superstorm Sandy was on the order of 20% more extreme owing to long-term sea level rise17,18, a signal of the same magnitude we have detected in the present study. Using this example as a scale, we conclude that climate change was indeed a significant contributor to sea ice loss during the summer of 2020 in the WS. Atmospheric variability in context To put 2020 WS sea ice advection into a larger scale context, we consider here the fundamental modes of Arctic atmospheric variability, i.e., the Arctic Oscillation (AO), the Arctic Dipole Mode (ADA), and the Barents Oscillation (BO)19,20. Each of these correspond to the principal components (PCs) of empirical orthogonal functions computed from monthly mean sea level pressure fields north of 30°N (Figs. 7 and S4). During January–March 2020, when sea ice was advected into the Wandel Sea, sea level pressure over the Arctic was low, with a sea level pressure pattern similar to that found in 2017 when the Beaufort Gyre reversed21,22. The resulting onshore ice motion contributed to anomalously thick ice north of Greenland. At this time, the AO and ADA were both very high (the AO was in fact a record), a situation not found in any other year over the 41-year time series. Interestingly, summer 2020 conditions show the opposite, with ice motion westward away from the WS and the AO and ADA near record negative values. It seems clear that the anomalous 2020 WS wind forcing was associated with anomalous large-scale surface wind patterns. Fig. 7: Atmospheric circulation and sea ice motion during 2020. Discussion and conclusions While primarily driven by unusual weather, climate change in the form of thinning sea ice contributed significantly to the record low August 2020 SIC in the WS. Several advection events, some relatively early in the melt season, transported sea ice out of the region and allowed the accumulation of heat from the absorption of solar radiation in the ocean. This heat was mixed upward and contributed to rapid melt during high wind events, notably between August 9 and 16. Ocean-forced melting in this area that is traditionally covered by thick, compact ice is a key finding of this study. However, in some ways this should not be surprising given that this area (like most areas of the Arctic) has experienced a long-term thinning trend. Given the long-term thinning trend and strong interannual variability in atmospheric forcing, it seems reasonable to expect that summer sea ice conditions in the WS will likely become more variable in the future. In fact, mean SIT at the start of summer in 2018 and 2019 was even thinner than in 2020, which implies that with 2020-type atmospheric forcing, we might have seen even lower August SICs in those years, relative to that observed in 2020. In other words, SIC in the WS is now poised to plunge to low summer values, given the right atmospheric forcing. So, is the LIA in trouble? The WS is a key part of the LIA, one that has recently experienced anomalous conditions. We have shown that climate change-associated thinning ice in this region is a prerequisite for the record low ice concentrations seen in August 2020. Further, the unusually high SIT at the start of 2020 suggests that a temporary replenishment of sea ice from other parts of the Arctic may do little to protect this area from eventual sea ice loss. Recent work indicates that while western and eastern sectors of the LIA have distinct physics11, they both are experiencing long-term sea ice thinning and thus are both vulnerable to the processes discussed in this study. Our work suggests a re-examination of climate model simulations in this area, since most do not predict summer 2020-level low SICs until several decades or more into the future. Given that most climate models presently feature a subgrid-scale thickness distribution23 its evolution over time in those models should be a focal point of future investigations (i.e., rather than simply focusing on grid-cell mean thickness). Coupled model simulations where atmosphere and ocean conditions are nudged to 2020 conditions would provide useful insights into the capabilities of the current generation of climate models to replicate our results. In addition, our results should be replicated with ice-ocean models using different resolutions and physics. While the WS is only one part of the LIA, our results should give us pause when making assumptions about the persistence and resilience of summer sea ice in the LIA. Currently, little is known about marine mammal densities and biological productivity in the WS and the broader LIA. Recent studies indicate there may be some transient benefits for polar bears in areas transitioning from thick multi-year ice to thinner first year ice as biological productivity in the system increases. However, this is largely the case in shallow water <300 m in depth and it is unclear if this will occur in multi-year ice regions elsewhere. The assumption that the LIA will be available as a refuge over the next century is inherently linked to projections about species’ population status, because for some species the LIA will be the last remaining summer sea ice habitat e.g. ref. 27. It is critical that future work quantify the resilience of this area for conservation and management of ice-dependent mammals under climate change. Methods Model and model configuration details PIOMAS consists of coupled sea ice and ocean model components. The sea ice model is a multi-category thickness and enthalpy distribution sea ice model which employs a teardrop viscous plastic rheology, a mechanical redistribution function for ice ridging and a LSR (line successive relaxation) dynamics solver. The model features 12 ice thickness categories covering ice up to 28 m thick. Sea ice volume per unit area h provides an “effective sea ice thickness” which includes open water (or leads) and ice of varying thicknesses. Unless otherwise noted, we refer to this quantity as sea ice thickness. The sea ice model is coupled with the Parallel Ocean Program model developed at the Los Alamos National Laboratory. The PIOMAS model domain is based on a curvilinear grid with the north pole of the grid displaced into Greenland. It covers the area north of 49°N and is one-way nested into a similar, but global, ice-ocean model. The average resolution of the model is 30 km but features its highest resolution in the Wandel Sea, with grid cell sizes on the order of 15 × 30 km. Vertical model resolution is 5 m in the upper 30 m, and less than 10 m at depths down to 100 m, a resolution that has been shown sufficient to provide a realistic representation of upper ocean heat fluxes and the NSTM. PIOMAS is capable of assimilating satellite sea ice concentration data using an optimal interpolation approach either over the whole ice-covered area or only near ice edge. In our run HIST, satellite ice concentrations are assimilated only near the ice edge (defined as 0.15 ice concentration). This means that no assimilation is conducted in the areas where both model and satellite ice concentrations are above 0.15. If the observed ice edge exceeds the model ice edge, then sea ice is added to the thinnest sea ice thickness category and sea surface temperature (SST) is set to the freezing point. If the model ice edge exceeds observations, excess ice is removed in all thickness categories proportionally. This ice-edge assimilation approach forces the simulated ice edge close to observations, while preventing satellite-derived ice concentrations (which can be biased low during the summer e.g. ref. ) from inaccurately correcting model ice concentrations in the interior of the ice pack. Ice concentrations used for assimilation are from the Hadley Centre (HadISST v1) for 1979-2006 and from the NSIDC near real time product for 2007 to present. PIOMAS also assimilates SST, using observations provided in the NCAR/NCEP reanalysis (see below for atmospheric forcing) which in turn are derived from NOAA’s OISSTv2.1 data set. SST assimilation is only conducted in the open water areas, not in the ice-covered areas to avoid introducing an additional heat source into the sea ice budget. For this study, we also conducted a number of sensitivity simulations in which no assimilation of ice concentration and SST is performed (see below). Daily mean NCEP/NCAR reanalysis data are used as atmospheric forcing, i.e., 10-m surface winds, 2-m surface air temperature, specific humidity, precipitation, evaporation, downwelling longwave radiation, sea level pressure, and cloud fraction. Cloud fraction is used to calculate downwelling shortwave radiation following Parkinson and Kellogg. Precipitation less evaporation is calculated from precipitation and latent heat fluxes provided by the reanalysis model and specified at monthly time resolution to allow the calculation of snow depth over sea ice and input of fresh water into the ocean. There is no explicit representation of melt-ponds in this version of PIOMAS. River runoff into the model domain is specified from climatology. Because of the uncertainty of net precipitation and river runoff, the surface ocean salinity is restored to a salinity climatology with a 3-year restoring constant. Surface atmospheric momentum and turbulent heat fluxes are calculated using a surface layer model that is part of the PIOMAS framework. Additional model information can be found in in Zhang and Rothrock. PIOMAS has undergone substantial validation and has been shown to simulate sea ice thickness with error statistics similar to the uncertainty of the observations. Validation results for ocean profiles for the WS are shown in S5. Sea ice mass and upper ocean heat budgets Components of the sea ice mass and upper ocean heat budgets are computed directly from model output and residuals. Fprod is calculated as Fprod = Δh/Δt – Fadv and Fbot = Fprod – Fatm-ice. All heat entering the uppermost ocean grid cell is used to melt ice until SIT = 0; however, subsurface shortwave radiation penetration and attenuation are allowed, which can warm the ocean below the uppermost grid cell. Focndyn over the upper 60 m (Eq. (1)) can be partitioned into Focndyn = Focnadv + Fdiff + Fconvect where Focnadv, Fdiff, and Fconvect are heat exchanges between the upper 60 m of the WS and the adjacent ocean via horizontal and vertical advection, horizonal and vertical diffusion, and vertical convection, respectively. Focnadv is calculated directly from model ocean temperatures and velocities, and the sum of Fdiff + Fconvect found as a residual, i.e., Fdiff + Fconvect = ΔH/Δt – Fatm-ocn − Fbot − Focnadv where ΔH/Δt is calculated directly from model temperature profiles. We find that Fdiff + Fconvect is negligible, meaning that horizontal and vertical advection terms (more formally, heat flux convergence) dominate. This is illustrated in Fig. S6, which shows a strong ocean warming within ~100 km of the north Greenland coast owing to lateral heat flux convergence. This is nearly exactly balanced (not shown) by the vertical fluxes, i.e., downwelling, in keeping with previous results. Finally, by comparing the heat budget for summer 2020 simulations with and without data assimilation (i.e., HIST vs. INIT), we find that this numerical effect produces only a negligible heat flux term and so is neglected here (it might be larger in other regions or over a longer time period of simulation). All ice mass and ocean heat budget terms are presented in units of meters of ice melt, assuming an ice density of 917 kg m−3 and latent heat of sea ice fusion of 3.293 × 105 J/kg. HIST, INIT, and ATMOS Runs The single HIST simulation uses data assimilation for the entire simulation period and is the basis for our analysis except for the sensitivity experiments described next. The INIT and ATMOS ensemble runs turn off the assimilation after May 31, 2020. For the JJA period of comparison, differences between the HIST run (which includes assimilation) and the equivalent members from the following ensemble runs (which do not include assimilation) are negligible. Attribution of drivers The INIT and ATMOS ensembles allow a partitioning of the proximate causes of the 2020 sea ice anomaly into those driven by the initial spring conditions (sea ice and ocean) and those related to the evolution of the atmosphere (winds, temperature, radiation, humidity) over the summer. To compute the relative contribution, we calculate spatially averaged SIC and SIT differences between the INIT and ATMOS ensemble medians and the HIST median at the time of the observed and simulated WS SIC sea ice minimum (August 14). The ensemble median here represents normal conditions as the reference to which conditions (sea ice for INIT, atmosphere for ATMOS) being tested are compared. The difference from HIST is considered the contribution of the respective 2020 condition, initial ice thickness for “INIT” and atmosphere for “ATMOS.” This difference in SIC (SIT) is 6.3% (0.35 m) for INIT and 31% (1.5 m) for ATMOS. Adding these differences yields a total SIC response of 37.3%, and with respective fractions for “INIT and ATMOS” yields a 17% (6.3%/37.3%) role of initial conditions and a 83% (31%/37.3%) role for the atmosphere. The impact on SIT is slightly higher with respective contributions of 19% and 81%. This partitioning can be used as a measure of the relative impacts of climate change and internal variability. Loosely following the framework of Trenberth at al. we assume atmospheric variability is governed by internal variability, and initial (i.e., spring) sea ice conditions to be driven by long-term climate change. Therefore the 20%/80% partitioning provides an approximate measure of the contributions of climate change and internal variability on the 2020 event. This separation is not perfect because atmospheric warming appears to be playing a role as evident in the fact that ATMOS ensemble members 2018/2019 both yield ice concentrations well below the 1979–2020 mean/median. The assumption that initial ice conditions are entirely due to climate change is also not entirely correct either, since internal variability also plays a role in sea ice conditions. Nevertheless, our experiments clearly show that the climate signal of thinning sea ice exerts an impact on the magnitude of internally driven extreme events in the WS. Moreover, the fact that dynamic thickening of WS spring sea ice conditions (likely the result of internal variability) did little to improve the resilience of sea ice later in the summer provides an indication that climate change-driven thinning will likely influence future events. Model uncertainties As noted, PIOMAS has undergone substantial validation with respect to sea ice thickness, volume and motion. A measure of the uncertainty of ice-mass budget terms can be obtained from a recent study that compared monthly advection and ice production terms from PIOMAS with another numerical model and estimates derived from satellite observations. Mass budget terms from the three different sources are highly correlated and provide confidence that the relationship of budget terms is correct even if their magnitudes may have error. In addition, our INIT and ATMOS model simulations incur additional uncertainties due to the lack of a direct feedback between the atmosphere and ice-ocean system. However, this problem is less severe in the summer season which is our focus here, because summer thermal contrasts are small between the marine surface and the atmosphere. Future experiments with coupled models that allow for a “replay” of observed variability will be needed to verify this. Sea Ice Outlook: 2023 August Report We thank all the groups and individuals who submitted August Outlooks in this 16th year of the Sea Ice Outlook. We also thank NSF for supporting this year's Outlook with funds from NSF award #1331083. This month we received 29 September pan-Arctic sea-ice extent forecasts. Of these, 10 included regional Alaska sea ice extent forecasts, and 7 included Antarctic sea-ice extent forecasts. The August median forecasted value for pan-Arctic September sea-ice extent is 4.60 million square kilometers with interquartile values of 4.35 and 4.80 million square kilometers, while individual forecasts range from 2.88 to 5.47 million square kilometers. We note that the lowest two forecasts predict a new record September sea-ice extent value (current record is September 2012, with a sea-ice extent of 3.57 million square kilometers), but these forecasts are outliers relative to the other contributions. The median Alaska sea-ice extent forecast is 0.44 million square kilometers and the median Antarctic sea-ice extent forecast is 17.70 million square kilometers, which would be the second lowest Antarctic September sea-ice extent on record. Three of the seven Antarctic forecasts predict a record low sea-ice extent (see below for further details). The August median forecast of 4.60 million square kilometers is slightly lower than the July median (4.66) and slightly higher than the June median (4.54). Interestingly, the interquartile range of August forecasts is slightly higher than the July interquartile range (0.45 compared to 0.36 million square kilometers), illustrating that inter-model uncertainty was not reduced between early July and early August forecasts. The August interquartile range is narrower than the June interquartile range of 0.56 million square kilometers. We also received 13 forecasts of the September Arctic sea-ice extent anomaly. The median anomaly sea-ice extent forecast is +0.17 million square kilometers, suggesting that September 2023 sea-ice extent will be slightly above the expected long term linear trend value. Anomaly forecasts range from -0.31 million square kilometers to +0.68 million square kilometers, and the interquartile range is 0.50 million square kilometers, slightly greater than the interquartile range for absolute September sea-ice extent mentioned above. Nine groups submitted supplemental materials (see: Contributor Full Reports and Supplemental Materials below). The supplemental material contents vary among the contributions, but they may include additional figures and information on methodology including (1) how the forecasts are produced; (2) number of ensemble members used in the forecasts; (3) whether and how bias-corrections are applied; (4) ensemble spread, range of forecasts, uncertainties and other statistics; and (5) whether or not post-processing was performed. This August Outlook Report was developed by lead author Mitch Bushuk, NOAA's Geophysical Fluid Dynamics Laboratory (Executive Summary, Overview of pan-Arctic forecasts), Edward Blanchard-Wrigglesworth, University of Washington (discussion of predictions from spatial fields), Walt Meier, National Snow and Ice Data Center (Discussion of current Arctic conditions); with contributions from Uma Bhatt, University of Alaska Fairbanks (Overview of Alaska regional forecasts, discussion of pan-Arctic anomaly sea-ice forecasts and ice conditions in the Bering and Chukchi seas); François Massonnet, UniversitĂ© catholique de Louvain (Discussion of Antarctic contributions); and with input from Matthew Fisher and the NSIDC Development Team, (statistics and graphs); Betsy Turner-Bogren and Helen Wiggins, ARCUS (report coordination and editing). Note: The Sea Ice Outlook provides an open process for those who are interested in Arctic sea ice to share predictions and ideas; the Outlook is not an operational forecast. 2023 SIO Forecasts (Pan-Attic, Alaska Region, Spatial Forecasts, and Antarctic) The August 2023 Outlook received 29 pan-Arctic contributions (Figure 1). This year's median forecasted value for pan-Arctic September sea-ice extent is 4.60 million square kilometers with interquartile values of 4.35 and 4.80 million square kilometers. This is lower than last year's August median forecast for September, but higher than the three previous years (2019–2021). The lowest sea-ice extent forecast is 2.88 million square kilometers, from UC Louvain, which would be a new record low for the satellite period (1979-present); the highest sea-ice extent forecast is 5.47 million square kilometers, from the NMEFC ArcCFPS Group, which would be the highest September extent since 2006. Two of the outlooks forecast a new record minimum September extent (UC Louvain and the AWI Consortium), with UC Louvain predicting a notable record and AWI Consortium forecasting a value close to the 2012 record low of 3.57 million square kilometers. The observed extent values are from the NSIDC Sea Ice Index (Fetterer et al., 2017), based on the NASA Team algorithm sea ice concentration fields distributed by the NASA Snow and Ice Distributed Active Archive Center (DAAC) at NSIDC (DiGirolamo et al., 2022; Meier et al., 2021). There are 12 dynamical model contributions and 17 contributions from statistical models. The dynamical models have a median forecast of 4.33 million square kilometers with an interquartile range of 4.20 to 4.70 million square kilometers (Figure 2). Compared to the dynamical models, the statistical models generally predict higher values, with a median forecast of 4.64 million square kilometers and an interquartile range of 4.48 to 4.82 million square kilometers. The Outlooks from all methods have medians and interquartile values below last year's observed September extent (4.90), with only a handful of methods yielding an extent higher than last year (Figure 2). Figure 1. Distribution of SIO contributors for August predictions of September 2023 pan-Arctic sea-ice extent. Public/citizen contributions include: Simmons and Sun, Image courtesy of Matthew Fisher, NSIDC. Figure 2. June (left), July (center), and August (right) 2023 pan-Arctic Sea Ice Outlook submissions, sorted by method. The August median of Statistical/ML method (center left in pink) is 4.64 million square kilometers and the median for Dynamic Methods (far right in green) is 4.33 million square kilometers. The flat line represents a single submission that used Mixed/Other Methods in June. There were no submissions using heuristic methods in July or August. Image courtesy of Matthew Fisher, NSIDC. Pan-Arctic Sea-Ice Extent Anomalies This is the third year that the SIO has solicited forecasts of September mean sea-ice extent anomalies. The pan-Arctic anomaly is the departure of the contributors' September extent Outlook relative to their adopted baseline trend (e.g., the trend in historical observations, model hindcasts, etc.). This is motivated by the prospect of reducing SIO extent forecast uncertainty that may originate from models having different trends, mean states, and post-processing methodologies. The 13 anomaly forecasts range from -0.31 to +0.68 million square kilometers, with four at or below and 9 above the contributors' baseline (Figure 3 top). The observed anomalies range from -1.24 (2012) to 0.79 (2006) million square kilometers (Figure 3 bottom). The pan-Arctic 2023 August SIO anomaly forecast has a median of +0.17 million square kilometers and an interquartile range of 0.50 million square kilometers. The uncertainty in the August SIO anomaly forecasts matches that in June, both of which are smaller than the large spread in July. Similar to the pan-Arctic forecasts, statistical methods generally predict higher positive anomalies than dynamical methods. Figure 3. Anomaly pan-Arctic August 2023 forecast ranked by submission (top) and observed anomalies with August forecasts (bottom). The median August 2023 forecast is 0.17 million square kilometers. Alaska Regional Forecasts The multimodel median for the August 2023 SIO forecast for the Alaska seas is 0.44 million square kilometers, and ranges from a minimum of 0.24 to a maximum of 0.81 million square kilometers (Figure 4). The dynamical model forecasts range from a minimum of 0.24 to maximum 0.81 million square kilometers with a median of 0.27 million square kilometers. The statistical model forecasts range from a minimum of 0.33 to a maximum of 0.64 million square kilometers with a median of 0.46 million square kilometers. The statistical forecasts display a smaller spread (interquartile range of 0.05) compared to the dynamical models (interquartile range of 0.48) (Figure 5). To place these in historical perspective, the September median sea-ice extent for the Alaska seas (Bering, Chukchi, and Beaufort) over 2007–2022 is 0.44 million square kilometers, making the forecast for August 2023 SIO forecast match the observed median value (see Figure 3 of 2022 Postseason SIO report). Figure 4. Distribution of SIO contributors for August estimates of September 2023 Alaska Regional sea-ice extent. Figure courtesy of Matthew Fisher, NSIDC. Figure 5. June (left), July (center), and August (right) 2023 Alaska Region Sea Ice Outlook submissions, sorted by method. The observed September 2022 sea-ice extent for the Bering-Chukchi-Beaufort seas was 0.47 million square kilometers. Figure courtesy of Matthew Fisher, NSIDC. Pan-Arctic Forecasts with Spatial Methods We received seven forecasts of September sea-ice probability (SIP), and five of ice-free date (IFD, using both a 15% and an 80% sea-ice concentration threshold). Figure 6. September sea ice probability forecasts from 7 models, the multi-model forecast (bottom middle), and the uncertainty across the forecasts, quantified as the standard deviation (bottom right). The SIP forecasts are in general similar to those in July, with a slight reduction in uncertainty. Interestingly, the forecasts show relatively high SIP values in the Laptev sea (with the exception of the IAP LASG forecast), which in recent years has often undergone significant melt. In contrast, the East Siberian 'sea ice tongue' is forecasted to mostly melt out or show reduced cover. Figure 7. Ice-free date (IFD) forecasts using a 15% SIC threshold (top row) and an 80% SIC threshold (bottom row). The IFD forecasts show that we are near the end of the melt season, with relatively small additional loss of sea ice (shown by the reduced covers of IFD during August or September). These forecasts however help understand the differences across models in their SIP forecasts above. For example, IAP LASG forecasts melt the ice cover during August around the Laptev sea, whereas other models' forecasts maintain the ice cover in this region. Regarding the IFD80 forecasts, there is forecast uncertainty regarding the SIC over the central Arctic region, with some models forecasting significant areas to remain above 80% SIC (GFDL, RASM), whereas others forecast SICs below 80% by the end of summer throughout the central Arctic (e.g., IAP LASG). This month we received two contributions of SIC and sea ice thickness (SIT) initial conditions (Figure 8). Figure 8. SIC and SIT ICs in the RASM and GFDL forecasts. While at large scale there is reasonable agreement in the SIC and SIT ICs, there are also significant differences in particular regions (especially in the Kara and East Siberian seas), which likely help explain some of the SIP and IFD forecast differences between the two models. Antarctic Forecasts Seven outlooks were received for this August call. All groups except one (NCEP-EMC) forecast below-average September mean Antarctic sea-ice extent (Figure 9). We note that the NCEP-EMC forecast is not bias corrected, and we place caution in interpreting it – especially given the increase of the predicted Antarctic sea-ice extent with lead time. On 20 August 2023, the anomaly of daily Antarctic sea-ice extent was 2.2 million square kilometers below the 1981-2020 average, according to the NSIDC sea ice index. This confirms the exceptional behavior of austral sea ice in 2023, that has been following record-low values for eight months. Last month, we stated that it was more likely than not that Antarctic sea-ice would hit a record low in September. Given the continued slow development of sea ice and the consistent sign of the forecasts, we now turn this level of confidence to "very likely". Figure 9. Time-series of observed September Antarctic sea-ice extent and June, July, August individual model forecasts. Also shown are the climatological and anomaly persistence forecasts. Current Conditions Pan-Arctic Conditions During the month of July, sea ice extent decline was near average at 93,300 sq km per day and was fairly steady through the month and near-average decline rates continued through mid-August. At the end of July, extent was 12th lowest in the 45-year satellite record. Thus, conditions were not extreme relative to recent years, but continued a trend of much lower summer extent than before 2007. Figure 10. Daily extent (based on a 5-day running average) through 14 August 2023 and comparisons to the past four years (2019-2022) and the record low minimum year of 2012. The 1981-2010 average is the dark gray line, surrounded by the inter-quartile range (medium gray) and the inter-decile range (light gray). Note: Figure 10 is from NSIDC Charctic, based on NSIDC Sea Ice Index, Fetterer et al., 2017 and the NASA Team sea-ice concentration product at NSIDC (DiGirolamo et al., 2022; Meier et al., 2021). The primary areas of loss during the month were in the Beaufort and Chukchi Seas, where the ice edge retreated far from the coast. The ice also retreated in the eastern East Siberian Sea and the Laptev Sea, though at the end of July a tongue of ice extending to near the coast in the western East Siberian Sea remained. Sea ice also extended to the coast of the Taymyr Peninsula, keeping the Northern Sea Route closed. By mid-August, the tongue of ice in the East Siberian Sea had largely eroded, but ice still remained in the proximity of the Taymyr Peninsula. Ice was beginning to clear out of the channels of the Canadian Archipelago by the end of July and by mid-August the Amundsen (southern) route through the Northwest Passage was open and the northern route was also clearing. Figure 11. Sea ice concentration for 20 August 2023 from the NSIDC Arctic Sea Ice News and Analysis, based on the NSIDC Sea Ice Index (Fetterer et al., 2017) and the NASA team sea ice concentration product at NSIDC (DiGirolamo et al., 2022; Meier et al., 2021). The 1981-2010 median ice edge location is in orange. Note: For current data, see NSIDC Arctic Sea Ice News and Analysis and NSIDC Sea Ice Index. Temperatures during July were moderate over most of the Arctic with the exception of very warm conditions in the eastern Beaufort Sea, where air temperatures at the 925 mb level of the atmosphere were up to 7 degrees C above average. Air temperatures over the Laptev Sea were 1 to 3 degrees C below average. Elsewhere, temperatures were near-average. Figure 12. July 2023 average air temperature anomaly at the 925 mb level. NOAA Physical Sciences Laboratory, Boulder, Colorado (Kalnay et al., 1996). The July sea-level pressure pattern was marked by low pressure over the Laptev Sea and high pressure centered over the Canadian Archipelago. This dipole-anomaly pattern resulted in a fairly strong pressure gradient across the central Arctic, which led to strengthened winds and greater sea ice transport from the Pacific side of the Arctic toward the Atlantic side. Figure 13. Sea level pressure for July 2023. NOAA Physical Sciences Laboratory, Boulder, Colorado (Kalnay et al., 1996). The 500 hPa ('Z500', about 5.5 kilometers up in the atmosphere) geopotential anomalies for 1 June through 16 August 2023 (calculated from the ERA5 reanalysis) show negative anomalies over the Siberian Arctic and positive anomalies over Svalbard and the CAA (Figure 14). The summer pattern of geopotential height anomalies at 500 hPa that covaries with September sea-ice extent can also help account for forecast uncertainty in SIO forecasts, with summers that have low Z500 anomalies tending to have more sea ice (and forecasts that tend to under-predict SIE) and vice versa (Blanchard-Wrigglesworth et al, 2023). In Figure 14 we show the canonical summer pattern, and the so-far (1 June—16 August) observed pattern of Z500 anomalies for summer 2023. Figure 14. (left) The regression of detrended June through September (JJAS) 500 hPa heights on detrended September sea-ice extent over 1979–2022 (in m per million square kilometers) - when central Arctic Z500 heights are low, September SIE tends to be anomalously high, and vice versa -, and (right) anomalous 1 June—16 August 2023 500 hPa heights. As we saw in July, the atmospheric pattern during the current summer is mostly orthogonal to the canonical pattern, and thus, to first order, we do not expect the current summer's circulation to strongly impact September pan-Arctic sea ice extent anomalies. Alaska Regional Conditions The seasonal cycle of daily sea-ice extent in the Alaskan seas in 2023 remained close to climatology during the melt season until mid-July. Since then, the sea-ice extent has fallen steeply, with mid-August values nearly reaching those from 2019 (Figure 15, top). The 2022 sea ice in the Chukchi was lower than mid-August values in 2023, while it was higher in 2022 than 2023 in the Beaufort. The August Alaska sea ice had lower concentrations in 2023 compared to 2022 (Figure 15, bottom). Figure 15. Daily seasonal cycle of Bering-Chukchi-Beaufort Sea Ice Extent from 2008 to present and showing the 1981-2010 median climatology (top). August 20th sea-ice concentration in 2022 (bottom left) and 2023 (bottom right). The average surface air temperature over the Arctic for this past year (October 2021-September 2022) was the 6th warmest since 1900. The last seven years are collectively the warmest seven years on record. Low pressure across the Alaska Arctic and northern Canada sustained warm summer temperatures over the Beaufort Sea and Canadian Archipelago. The Arctic continues to warm more than twice as fast as the rest of the globe, with even greater warming in some locations and times of year. 2022 Arctic sea ice extent was similar to 2021 and well below the long-term average. August 2022 mean sea surface temperatures continued to show warming trends for 1982-2022 in most ice-free regions of the Arctic Ocean. SSTs in the Chukchi Sea were anomalously cool in August 2022. Most regions of the Arctic continued to show increased ocean plankton blooms, or ocean primary productivity, over the 2003-22 period, with the greatest increases in the Eurasian Arctic and Barents Sea. Satellite records from 2009 to 2018 show increasing maritime ship traffic in the Arctic as sea ice declines. The most significant increases in maritime traffic are occurring from the Pacific Ocean through the Bering Strait and Beaufort Sea. NASA’s Oceans Melting Greenland mission used cutting-edge technology to demonstrate that rising ocean temperatures along Greenland’s continental shelf are contributing to ice loss through melting glaciers at the ice sheet’s margins. June 2022 terrestrial snow cover was unusually low over both the North American (2nd lowest in the 56-year record) and Eurasian Arctic (3rd lowest in the record). Winter accumulation was above average, but early snow melt in a warming Arctic contributed to the overall low snow cover. A significant increase in Arctic precipitation since the 1950s is now detectable across all seasons. Wetter-than-normal conditions were observed from October 2021 through September 2022, in what was the 3rd wettest year of the past 72 years. The Greenland Ice Sheet experienced its 25th consecutive year of ice loss. In September 2022, unprecedented late-season warming created surface melt conditions over 36% of the ice sheet, including at the 10,500 ft ice sheet summit. Tundra greening declined from the record high values of the previous two years, with high productivity in most of the North American Arctic, but unusually low productivity in northeastern Siberia. Wildfires, extreme weather events, and other disturbances have become more frequent, influencing the variability of tundra greenness. Striking differences were observed between lake ice durations in Eurasia and North America, with substantially longer than average ice durations in Eurasia and predominantly shorter in North America. Freeze-up of Arctic lakes is occurring later in most of North America, especially in Canada. The distribution, conservation status, and ecology of most Arctic pollinators are poorly known though these insects are critically important to Arctic ecosystems and the food systems of Arctic Indigenous Peoples and Arctic residents. Coordinated long-term monitoring, increased funding, and emerging technologies can improve our understanding of Arctic pollinator habitats and status, and inform effective conservation strategies. In 2022, despite an outbreak of highly pathogenic avian influenza affecting birds throughout North America and variable spring weather conditions, the population sizes of most Arctic geese remained high with increasing or stable trends. Multiple geese species provide food and cultural significance for many peoples. In contrast, communities in the northern Bering and southern Chukchi Sea region reported higher-than-expected seabird die-offs for the sixth consecutive year. Tracking the duration, geographic extent, and magnitude of seabird bird die-offs across Alaska’s expansive and remote coastline is only possible through well-coordinated communication and a dedicated network of Tribal, State, and Federal partners. People experience the consequences of a rapidly changing Arctic as the combined effects of physical conditions, responses of biological resources, impacts on infrastructure, decisions influencing adaptive capacities, and environmental and international influences on economics and well-being. Living and innovating in Arctic environments over millennia, Indigenous Peoples have evolved holistic knowledge providing resilience and sustainability. Indigenous expertise is augmented by scientific abilities to reconstruct past environments and to model and predict future changes. Decision makers (from communities to governments) have the skills necessary to apply this experience and knowledge to help mitigate and adapt to a rapidly changing Arctic. Addressing unprecedented Arctic environmental changes requires listening to one another, aligning values, and collaborating across knowledge systems, disciplines, and sectors of society. What is the longest river in the world? The largest river on the planet, the Amazon, forms from the confluence of the SolimĂ”es (the upper Amazon River) and the Negro at the Brazilian city of Manaus in central Amazonas. At the river conjunction, the muddy, tan-colored waters of the SolimĂ”es meet the “black” water of the Negro River. The unique mixing zone where the waters meet extends downstream through the rainforest for hundreds of miles, and attracts tourists from all over the world, which has contributed to substantial growth in the city of Manaus. It is the vast quantity of sediment eroded from the Andes Mountains that gives the SolimĂ”es its tan color. By comparison, water in the Negro derives from the low jungles where reduced physical erosion of rock precludes mud entering the river. In place of sediment, organic matter from the forest floor stains the river the color of black tea. The SolimĂ”es provides nutrient-rich mud to lakes on the floodplain (lower right). The ecology of muddy lakes differs correspondingly from that of nutrient-poor, blackwater rivers and lakes. SolimĂ”es water can be seen leaking into the Negro west of the main meeting zone (lower left). The SolimĂ”es is much shallower than the Negro because it has filled its valley and bed with great quantities of sediment since the valleys were excavated. Widths of the rivers differ for this reason Global Temperature Key Takeaway: Earth’s global average surface temperature in 2020 statistically tied with 2016 as the hottest year on record, continuing a long-term warming trend due to human activities. This graph (graph_globaltemperature.txt) shows the change in global surface temperature compared to the long-term average from 1951 to 1980. The year 2020 statistically tied with 2016 for the hottest year on record since record keeping began in 1880 (source: graph_globaltemperature.txt). NASA’s analyses generally match independent analyses prepared by National Oceanic and Atmospheric Administration (NOAA) and other institutions. The animation on the right shows the change in global surface temperatures. Dark blue shows areas cooler than average. Dark red shows areas warmer than average. Short-term variations are smoothed out using a 5-year running average to make trends more visible in this map. Methane Key Takeaway: Methane is a powerful heat-trapping gas. The amount of methane in the atmosphere is increasing due to human activities. Methane Basics Methane (CH4) is a powerful greenhouse gas, and is the second-largest contributor to climate warming after carbon dioxide (CO2). A molecule of methane traps more heat than a molecule of CO2, but methane has a relatively short lifespan of 7 to 12 years in the atmosphere, while CO2 can persist for hundreds of years or more. Methane comes from both natural sources and human activities. An estimated 60% of today’s methane emissions are the result of human activities. The largest sources of methane are agriculture, fossil fuels, and decomposition of landfill waste. Natural processes account for 40% of methane emissions, with wetlands being the largest natural source. (Learn more about the Global Methane Budget.) The concentration of methane in the atmosphere has more than doubled over the past 200 years. Scientists estimate that this increase is responsible for 20 to 30% of climate warming since the Industrial Revolution (which began in 1750). Tracking Methane Although it’s relatively simple to measure the amount of methane in the atmosphere, it’s harder to pinpoint where it’s coming from. NASA scientists are using several methods to track methane emissions. One tool that NASA uses is the Airborne Visible InfraRed Imaging Spectrometer - Next Generation, or AVIRIS-NG. This instrument, which gets mounted onto research planes, measures light that is reflected off Earth’s surface. Methane absorbs some of this reflected light. By measuring the exact wavelengths of light that are absorbed, the AVIRIS-NG instrument can determine the amount of greenhouse gases present. NASA added the Earth Surface Mineral Dust Source Investigation (EMIT) instrument to the International Space Station in 2022. Though built principally to study dust storms and sources, researchers found that it could also detect large methane sources, known as “super-emitters.” These aircraft and satellite instruments are finding methane rising from oil and gas production, pipelines, refineries, landfills, and animal agriculture. In some cases, these measurements have led to leaks being fixed, including suburban gas leaks and faulty equipment in oil and gas fields. The Arctic is a source of natural methane from wetlands, lakes, and thawing permafrost. Although a warming climate could change these emissions, scientists do not yet think it will drive a major increase. To this end, NASA’s Arctic Boreal and Vulnerability Experiment, or ABoVE, has been measuring methane coming from natural sources like thawing permafrost in Alaska and Canada. Data Notes and Sources NOAA’s methane data comes from a globally-distributed network of air sampling sites. https://gml.noaa.gov/ccgg/trends_ch4/ Ice core data are from Law Dome (Antarctica) and Summit (Greenland) ice cores, from Etheridge, D.M., L.P. Steele, R.J. Francey, and R.L. Langenfelds, Atmospheric methane between 1000 AD and present: Evidence of anthropogenic emissions and climatic variability. Journal of Geophysical Research, 103, D13, 15,979-15,993, 1998. Data archived at the Carbon Dioxide Information Analysis Center https://cdiac.ess-dive.lbl.gov/trends/atm_meth/lawdome_meth.htm Ocean Warming Ninety percent of global warming is occurring in the ocean, causing the water’s internal heat to increase since modern recordkeeping began in 1955, as shown in the upper chart. (The shaded blue region indicates the 95% margin of uncertainty.) This chart shows annual estimates for the first 2,000 meters of ocean depth. Each data point in the upper chart represents a five-year average. For example, the 2020 value represents the average change in ocean heat content (since 1955) for the years 2018 up to and including 2022. The lower chart tracks monthly changes in ocean heat content for the entire water column (from the top to the bottom of the ocean) from 1992 to 2019, integrating observations from satellites, in-water instruments, and computer models. Both charts are expressed in zettajoules. Heat stored in the ocean causes its water to expand, which is responsible for one-third to one-half of global sea level rise. Most of the added energy is stored at the surface, at a depth of zero to 700 meters. The last 10 years were the ocean’s warmest decade since at least the 1800s. The year 2022 was the ocean’s warmest recorded year and saw the highest global sea level. Ice Sheets Key Takeaway: Antarctica is losing ice mass (melting) at an average rate of about 150 billion tons per year, and Greenland is losing about 270 billion tons per year, adding to sea level rise. Data from NASA's GRACE and GRACE Follow-On satellites show that the land ice sheets in both Antarctica (upper chart) and Greenland (lower chart) have been losing mass since 2002. The GRACE mission ended in June 2017. The GRACE Follow-On mission began collecting data in June 2018 and is continuing to monitor both ice sheets. This record includes new data-processing methods and is continually updated as more numbers come in, with a delay of up to two months. This is important because the ice sheets of Greenland and Antarctica store about two-thirds of all the fresh water on Earth. They are losing ice due to the ongoing warming of Earth’s surface and ocean. Meltwater coming from these ice sheets is responsible for about one-third of the global average rise in sea level since 1993. Sea Level Key Takeaway: Global sea levels are rising as a result of human-caused global warming, with recent rates being unprecedented over the past 2,500-plus years. Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers, and the expansion of seawater as it warms. The first graph tracks the change in global sea level since 1993, as observed by satellites. The second graph, which is from coastal tide gauge and satellite data, shows how much sea level changed from about 1900 to 2018. Items with pluses (+) are factors that cause global sea level to increase, while minuses (-) are what cause sea level to decrease. These items are displayed at the time they were affecting sea level. EVIDENCES How Do We Know Climate Change Is Real? There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause. TAKEAWAYS While Earth’s climate has changed throughout its history, the current warming is happening at a rate not seen in the past 10,000 years. According to the Intergovernmental Panel on Climate Change (IPCC), "Since systematic scientific assessments began in the 1970s, the influence of human activity on the warming of the climate system has evolved from theory to established fact."1 Scientific information taken from natural sources (such as ice cores, rocks, and tree rings) and from modern equipment (like satellites and instruments) all show the signs of a changing climate. From global temperature rise to melting ice sheets, the evidence of a warming planet abounds. The rate of change since the mid-20th century is unprecedented over millennia. Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives. The current warming trend is different because it is clearly the result of human activities since the mid-1800s, and is proceeding at a rate not seen over many recent millennia.1 It is undeniable that human activities have produced the atmospheric gases that have trapped more of the Sun’s energy in the Earth system. This extra energy has warmed the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred. Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate. Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th century.2 Many of the science instruments NASA uses to study our climate focus on how these gases affect the movement of infrared radiation through the atmosphere. From the measured impacts of increases in these gases, there is no question that increased greenhouse gas levels warm Earth in response. "Scientific evidence for warming of the climate system is unequivocal." - Intergovernmental Panel on Climate Change Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. Carbon dioxide from human activities is increasing about 250 times faster than it did from natural sources after the last Ice Age. As evidĂȘncias para mudanças ClimĂĄticas rĂĄpidas sĂŁo convincentes: A temperatura global estĂĄ aumentando A temperatura mĂ©dia da superfĂ­cie do planeta aumentou cerca de 2 graus Fahrenheit ( 1 graus Celsius ) desde o final do sĂ©culo XIX, uma mudança impulsionada em grande parte pelo aumento das emissĂ”es de diĂłxido de carbono na atmosfera e em outras atividades humanas.4 A maior parte do aquecimento ocorreu nos Ășltimos 40 anos, sendo os sete anos mais recentes os mais quentes. Os anos de 2016 e 2020 estĂŁo empatados no ano mais quente jĂĄ registrado.5 O oceano estĂĄ ficando mais quente O oceano absorveu grande parte desse aumento de calor, com os 100 metros superiores ( cerca de 328 pĂ©s ) do oceano mostrando um aquecimento de 0,67 graus Fahrenheit ( 0,33 graus Celsius ) desde 1969.6 A Terra armazena 90% da energia extra no oceano. As folhas de gelo estĂŁo encolhendo As camadas de gelo da GroenlĂąndia e da AntĂĄrtica diminuĂ­ram em massa. Dados da experiĂȘncia de recuperação de gravidade e clima da NASA mostram que a GroenlĂąndia perdeu uma mĂ©dia de 279 bilhĂ”es de toneladas de gelo por ano entre 1993 e 2019, enquanto a AntĂĄrtica perdeu cerca de 148 bilhĂ”es de toneladas de gelo por ano.7 Geleiras estĂŁo recuando As geleiras estĂŁo recuando em quase todo o mundo —, incluindo nos Alpes, Himalaia, Andes, Montanhas Rochosas, Alasca e África.8 A cobertura de neve estĂĄ diminuindo ObservaçÔes por satĂ©lite revelam que a quantidade de cobertura de neve na primavera no HemisfĂ©rio Norte diminuiu nas Ășltimas cinco dĂ©cadas e a neve estĂĄ derretendo mais cedo. CrĂ©dito da imagem: NASA / JPL-Caltech9 O nĂ­vel do mar estĂĄ aumentando O nĂ­vel global do mar subiu cerca de 8 polegadas ( 20 centĂ­metros ) no sĂ©culo passado. A taxa nas Ășltimas duas dĂ©cadas, no entanto, Ă© quase o dobro da do sĂ©culo passado e acelera um pouco a cada ano.10 Gelo do Mar Ártico estĂĄ diminuindo Tanto a extensĂŁo quanto a espessura do gelo do mar do Ártico diminuĂ­ram rapidamente nas Ășltimas dĂ©cadas.11 Eventos extremos estĂŁo aumentando em frequĂȘncia O nĂșmero de eventos recordes de alta temperatura nos Estados Unidos tem aumentado, enquanto o nĂșmero de eventos recordes de baixa temperatura vem diminuindo desde 1950. Os EUA tambĂ©m testemunharam um nĂșmero crescente de intensos eventos de chuvas.12 A acidificação do oceano estĂĄ aumentando Desde o inĂ­cio da Revolução Industrial, a acidez das ĂĄguas superficiais do oceano aumentou cerca de 30%.13,14 Esse aumento ocorre devido ao fato de os seres humanos emitirem mais diĂłxido de carbono na atmosfera e, portanto, serem mais absorvidos pelo oceano. O oceano absorveu entre 20% e 30% do total de emissĂ”es antropogĂȘnicas de diĂłxido de carbono nas Ășltimas dĂ©cadas ( 7,2 a 10,8 bilhĂ”es de toneladas mĂ©tricas por ano ).15,16 CrĂ©dito da imagem: NOAA CAUSES The Causes of Climate Change Human activities are driving the global warming trend observed since the mid-20th century. TAKEAWAYS The greenhouse effect is essential to life on Earth, but human-made emissions in the atmosphere are trapping and slowing heat loss to space. Five key greenhouse gases are carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, and water vapor. While the Sun has played a role in past climate changes, the evidence shows the current warming cannot be explained by the Sun. Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the "greenhouse effect"1 — warming that results when the atmosphere traps heat radiating from Earth toward space. Life on Earth depends on energy coming from the Sun. About half the light energy reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and radiated in the form of infrared heat. About 90% of this heat is then absorbed by greenhouse gases and re-radiated, slowing heat loss to space. Four Major Gases That Contribute to the Greenhouse Effect: FORCING: Something acting upon Earth's climate that causes a change in how energy flows through it (such as long-lasting, heat-trapping gases - also known as greenhouse gases). These gases slow outgoing heat in the atmosphere and cause the planet to warm. Carbon Dioxide A vital component of the atmosphere, carbon dioxide (CO2) is released through natural processes (like volcanic eruptions) and through human activities, such as burning fossil fuels and deforestation. Methane Like many atmospheric gases, methane comes from both natural and human-caused sources. Methane comes from plant-matter breakdown in wetlands and is also released from landfills and rice farming. Livestock animals emit methane from their digestion and manure. Leaks from fossil fuel production and transportation are another major source of methane, and natural gas is 70% to 90% methane. Nitrous Oxide A potent greenhouse gas produced by farming practices, nitrous oxide is released during commercial and organic fertilizer production and use. Nitrous oxide also comes from burning fossil fuels and burning vegetation and has increased by 18% in the last 100 years. Chlorofluorocarbons (CFCs) These chemical compounds do not exist in nature – they are entirely of industrial origin. They were used as refrigerants, solvents (a substance that dissolves others), and spray can propellants. Another Gas That Contributes to the Greenhouse Effect: FEEDBACKS: A process where something is either amplified or reduced as time goes on, such as water vapor increasing as Earth warms leading to even more warming. Water Vapor Water vapor is the most abundant greenhouse gas, but because the warming ocean increases the amount of it in our atmosphere, it is not a direct cause of climate change. EFFECTS The Effects of Climate Change The effects of human-caused global warming are happening now, are irreversible for people alive today, and will worsen as long as humans add greenhouse gases to the atmosphere. TAKEAWAYS We already see effects scientists predicted, such as the loss of sea ice, melting glaciers and ice sheets, sea level rise, and more intense heat waves. Scientists predict global temperature increases from human-made greenhouse gases will continue. Severe weather damage will also increase and intensify. Earth Will Continue to Warm and the Effects Will Be Profound Global climate change is not a future problem. Changes to Earth’s climate driven by increased human emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic ranges are shifting, and plants and trees are blooming sooner. Effects that scientists had long predicted would result from global climate change are now occurring, such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves. "The magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related losses and damages escalate with every increment of global warming." - Intergovernmental Panel on Climate Change Some changes (such as droughts, wildfires, and extreme rainfall) are happening faster than scientists previously assessed. In fact, according to the Intergovernmental Panel on Climate Change (IPCC) — the United Nations body established to assess the science related to climate change — modern humans have never before seen the observed changes in our global climate, and some of these changes are irreversible over the next hundreds to thousands of years. Scientists have high confidence that global temperatures will continue to rise for many decades, mainly due to greenhouse gases produced by human activities. The IPCC’s Sixth Assessment report, published in 2021, found that human emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since 1850-1900.1 The global average temperature is expected to reach or exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth. The severity of effects caused by climate change will depend on the path of future human activities. More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. So, if we can reduce emissions, we may avoid some of the worst effects. "The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss the brief, rapidly closing window to secure a liveable future."2 SOLUTIONS - Intergovernmental Panel on Climate Change Sustainability and Government Resources NASA is an expert in climate and Earth science. While its role is not to set climate policy or prescribe particular responses or solutions to climate change, its job does include providing the scientific data needed to understand climate change. NASA then makes this information available to the global community – the public, policy-, and decision-makers and scientific and planning agencies around the world. (For more information, see NASA's role.) With that said, NASA takes sustainability very seriously. NASA’s sustainability policy is to execute its mission as efficiently as possible. In doing so, we continually improve our space and ground operations. Sustainability involves taking action now to protect the environment for both current and future living conditions. In implementing sustainability practices, NASA supports its missions by reducing risks to the environment and our communities. In executing its mission, NASA's sustainability objectives are to: increase energy efficiency; increase the use of renewable energy; measure, report, and reduce NASA's direct and indirect greenhouse gas emissions; conserve and protect water resources through efficiency, reuse, and stormwater management; eliminate waste, prevent pollution, and increase recycling; leverage agency acquisitions to foster markets for sustainable technologies and environmentally preferable materials, products, and services; design, construct, maintain, and operate high-performance sustainable buildings; utilize power management options and reduce the number of agency data centers; support economic growth and livability of the communities where NASA conducts business; evaluate agency climate change risks and vulnerabilities and develop mitigation and adaptation measures to manage both the short-and long-term effects of climate change on the agency's mission and operations; raise employee awareness and encourage each individual in the NASA community to apply the concepts of sustainability to every aspect of their daily work to achieve these goals; maintain compliance with all applicable federal, state, local or territorial law and regulations related to energy security, a healthy environment, and environmentally-sound operations; and comply with internal NASA requirements and agreements with other entities. What is the gray circle in the middle of some of the extent maps? Not all satellites pass close enough to the North Pole for their sensors to collect data there. This lack of data is indicated by a gray circle, or “pole hole,” in each image. Created: June 2008 Related question: How will we know if ice at the North Pole melts? Return to top How will we know if ice at the North Pole melts? Historically, lack of satellite data directly over the North Pole has not concerned scientists; they have always assumed that the area underneath is covered with sea ice. However, in recent years, the possibility that there will be no sea ice over the North Pole in summer has become more likely. Fortunately, some satellite sensors are able to obtain data directly over the North Pole; Data from these satellites could be used to fill in data that are missing from other satellite records. For example, the NASA Advanced Microwave Scanning Radiometer—Earth Observing System (AMSR-E) could fill in some missing data because it has a smaller pole hole than other satellites. Or, scientists could use the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) instrument, which does collect data over the North Pole and thus has no pole hole. To learn more about how scientists study sea ice, see our Learn about Sea Ice: Science page. Created: June 2008 Related questions: What is the gray circle in the middle of some of the extent maps? Will the ice at the North Pole melt? Return to top What satellite is the sea ice data from? The “Daily image update,” as well as many of the images shown in Arctic Sea Ice News & Analysis, are derived from the Sea Ice Index data product. The Sea Ice Index relies on NASA-developed methods to estimate sea ice conditions using passive-microwave data from the Defense Meteorological Satellite Program (DMSP) the Special Sensor Microwave Imager/Sounder (SSMIS). The basis for the Sea Ice Index is the data set, “Near-Real-Time DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations,” and the NASA-produced “Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data.” For more details, see the Sea Ice Index. Updated: June 2009 Return to top Why is the Sea Ice Index product used to study sea ice? The passive-microwave data used for the Sea Ice Index is especially helpful because the sensor can “see” through clouds and deliver data even during the six months of Arctic darkness and frequently cloudy conditions. Some other satellite sensors cannot penetrate clouds to take data, so the results are sporadic and dependent upon weather conditions. Still other sensors can see through clouds, but they do not cover the entire region of the globe where sea ice exists every day, making near-real-time monitoring difficult. Furthermore, some sensors cannot provide information in winter, when polar darkness prevails. The passive microwave sea ice record dates back to 1979, one of the longest environmental data sets we know of. This provides a long-term product that consistently tracks changes in the ice cover over many years, lending additional confidence to the trends that we observe. So, although NSIDC refers to additional satellite data in developing our analysis, we primarily rely on passive-microwave data for Arctic Sea Ice News & Analysis images and content, and for tracking long-term change. Created: June 2008 Return to top Sometimes readers report that our maps show ice incorrectly, compared to on-the-ground observations or other data sources. Why is this? Quality control for near-real-time-data One reason that ice extent images may have errors is that the satellite derived images in our Daily Image Update are near-real time and have not yet undergone rigorous quality control to correct for conflicting information that is especially likely along coastlines. Areas near land may show some ice coverage where there is not any because the sensor’s resolution is not fine enough to distinguish ice from land when a pixel overlaps the coast. Sometimes, the data we receive have errors in the geolocation data, caused by problems with the instrument, which could affect where ice appears. Near-real-time data may also have areas of missing data, displayed on the daily map as gray wedges, speckles, or spider web patterns. In addition, satellite sensors occasionally have problems and outages, which can affect the near-real-time data. We correct these problems in the final sea ice products, which replace the near-real-time data in about six months to a year. Despite areas of inaccuracy, near-real-time data are still useful for assessing changes in sea ice coverage, particularly when averaged over an entire month. The monthly average image is more accurate than the daily images because weather anomalies and other errors are less likely to affect it. Because of the limitations of near-real-time data, they should be used with caution when seeking to extend a sea ice time series, and should not be used for operational purposes such as navigation. To look at monthly images that have been through quality control, click on “Archived Data and Images” on the Sea Ice Index. Resolution of the data Another reason for apparent errors in ice extent is that the data are averaged over an area of 25 kilometers by 25 kilometers (16 by 16 miles). This means that the ice edge could be off by as much as 25 to 50 kilometers (16 to 31 miles) in passive-microwave data, compared to higher-resolution satellite systems. In addition, we define ice extent as any 25 by 25 kilometer grid cell with with an average of ?at least 15 percent ice. Ice-free areas may nevertheless exist within an area that is defined by our algorithms as ice covered. Passive microwave data characteristics The daily image is derived from remotely sensed passive microwave data, which can be collected even during cloudy or dark conditions. Passive microwave data may show ice where none actually exists due to signal variation between land and water along coastlines, or because of atmospheric interference from rain or high winds over the ice-free ocean. Reasons that passive microwave data may not detect ice include the presence of thin, newly formed ice; the shift in albedo of actively melting ice; and atmospheric interference. Thin, newly formed ice is consistently underestimated by these data. Centers such as the U.S. National Ice Center and the Canadian Ice Service that publish sea ice data for navigation employ higher spatial resolution data that is better able to detect such thin ice. Despite the limitations in passive microwave data, they still yield good large-scale estimates for the overall extent pattern and values of the ice. Plus, the limitations are consistent, affecting the data this year in the same way they have affected it in previous years. So when comparing from year to year, these types of errors do not affect the comparison. While passive microwave data products may not show as much detail or be as accurate “on the ground” as other satellite data, they provide a consistent time series to track sea ice extent going back to 1979. Higher resolution sensors only go back to 2002. This type of long-term, consistent data is important to scientists who study whether or not change is taking place in a system. To learn more about how scientists study sea ice, see our Learn about Sea Ice: Science page. Updated: March 2012 Related question: Do your data undergo quality control? Return to top Do your data undergo quality control? The daily and monthly images that we show in Arctic Sea Ice News & Analysis are near-real-time data. Near-real-time data do not receive the rigorous quality control that final sea ice products enjoy, but it allows us to monitor ice conditions as they develop. Several possible sources of error can affect near-real-time images. Areas near land may show some ice coverage because the sensor has a coarse resolution and though a coastal filter is applied, it is not effective in some situations. Sometimes, the data we receive have geolocation errors, which could affect where ice appears. Near-real-time data may also have areas of missing data, displayed on the daily map as gray wedges, speckles, or spider web patterns. In addition, satellite sensors occasionally have problems and outages, which can affect the near-real-time data. We correct these problems in the final sea ice products, which replace the near-real-time data in about six months to a year. Despite its areas of inaccuracy, near-real-time data are still useful for assessing changes in sea ice coverage, particularly when averaged over an entire month. The monthly average image is more accurate than the daily images because weather anomalies and other errors are less likely to affect it. Because of the limitations of near-real-time data, they should be used with caution when seeking to extend a sea ice time series, and should not be used for operational purposes such as navigation. To look at monthly images that have been through quality control, click on “Archived Data and Images” on the Sea Ice Index. Updated: June 2009 Return to top What is the error range for your images? NSIDC does not have error bars on the time series plot shown in the “Daily Image Update” and the daily time series plot (usually labeled “Figure 2”) because we strive to keep the images concise and easy to read. Plus, the error bars would be quite small compared to the total extent values in the images. We estimate error based on accepted knowledge of the sensor capabilities and analysis of the amount of “noise,” or daily variations not explained by changes in weather variables. For average relative error, or error relative to other years, the error is approximately 20,000 to 30,000 square kilometers (7,700 to 11,600 square miles), a small fraction of the total existing sea ice. For average absolute error, or the amount of ice that the sensor measures compared to actual ice on the ground, the error is approximately 50 thousand to 1 million square kilometers (19,300 to 386,100 square miles), varying over the year. During summer melt and freeze-up in the fall, the extent may be underestimated by 1 million square miles; during mid and late winter before melt starts, the error will be on the low end of the estimates. It is important to note that while the magnitude of the error varies through the year, it is consistent year to year. This gives scientists high confidence in interannual trends at a given time of year. The absolute error values may seem high, but it is important to note that each year has roughly the same absolute error value, so the decline over the long term remains clear. NSIDC has high confidence in sea ice trend statistics and the comparison of sea ice extent between years. Created: June 2008 Related questions: Sometimes readers report that our maps show ice incorrectly. Why? What is standard deviation and how does it relate to sea ice extent? Return to top Why do you use the 1981 to 2010 average for comparisons? NSIDC scientists use the 1981 to 2010 average because it provides a consistent baseline for year-to-year comparisons of sea ice extent. Thirty years is considered a standard baseline period for weather and climate, and the satellite record is now long enough to provide a thirty year baseline period. If we were to recalculate the baseline every year to incorporate the most recent year of data, we couldn’t meaningfully compare between recent years. To borrow a common phrase, we would be comparing apples and oranges. The problem with relying on a sliding average becomes clear over time, when we try to compare new years of data with previous years. For example, if we rely on a standard, unchanging baseline like 1981 to 2010, we can easily and clearly compare September 2007 and September 2008 with each other. However, if we were to use a sliding baseline of 1979 to 2006 for September 2007, and a sliding baseline of 1979 to 2007 for September 2008, we would no longer be comparing “apples to apples” when we compared the two years to the baseline. Arctic Sea Ice News and Analysis and the Sea Ice Index moved to a baseline period of 1981 to 2010 starting July 1, 2013. Previously, NSIDC had used 1979 to 2000 as the comparison period. Updated: July 2013 Related questions: What is the difference between sea ice area and extent? Are you updating the 1981-2010 average to the 1991-2020 average for comparisons? Return to top Are you updating the 1981-2010 average to the 1991-2020 average for comparisons? No. A 30-year climatology is commonly used as a reference period in weather and climate to define “normal” conditions. Thirty years is long enough to average out most natural variations in climate, like El Niño, that can affect the average in the short term. A norm or an average for weather is geared towards operational type of applications. For instance, is the weather warmer than average compared to recent years? If so, should farmers plant crops earlier than last year? Therefore, weather forecast services update their climatology with each new decade. The US National Weather Service, for instance, updated their period from 1981 to 2010 to 1991 to 2020. NSIDC scientists decided against such a shift for analyzing changes to Arctic sea ice. A shifting baseline makes tracking long-term climate change more complicated. As the baseline shifts, anomalies (amount above or below “normal”) and relative (percent per decade) trends will change. For climate, we want to look at long-term changes, so having a consistent baseline makes more sense. That way when new data is collected, there is a consistent baseline for decadal or longer evaluation of change. Ideally, this baseline period would be relatively stable and without much of a trend. This is particularly a problem for Arctic sea ice where the last 10 years have had several extremely low extents. Including these recent years hardly represents “normal” in terms of the long-term climate. If we switch to the 1991-2020 average, then all previous statistics can not be compared with the new baseline. And the new baseline will be more skewed by the downward trend. This would make relative trends, represented as percents per decade, larger in magnitude than they are with 1981-2010 average. For this reason, we plan to maintain the 1981-2010 period as our standard climate record. The period comprises the earliest three full decades in the continuous satellite record. The data for this period have been well validated and consistency has been maintained through careful calibrations between different sensors used in the time series. As a note, ASINA’s sea ice analysis tool allows users to see data relative to a customizable climatology. Updated: October 2021 Return to top The daily image update isn’t current; why? The daily image update is produced from near-real-time operational satellite data, with a data lag of approximately one day. However, visitors may notice that the date on the image is occasionally more than one day behind. Occasional short-term delays and data outages do occur and are usually resolved in a few days. Updated: February 2009 Related question: Do your data undergo quality control? Return to top Are there other sources of sea ice data? How do these sources differ from NSIDC data? Other researchers and organizations monitor sea ice independently, using a variety of sensors and algorithms. While these sources agree broadly with NSIDC data, extent measurements differ because of variation in the formulas (algorithms) used for the calculation, the sensor used, the threshold method to determine whether a region is “ice-covered,” and processing methods. NSIDC’s methods are designed to be as internally consistent as possible to allow for tracking of trends and variability throughout our data record. Links to other sources of sea ice data are listed below: University of Bremen Daily Updated AMSR-E Sea Ice Maps Nansen Environmental & Remote Sensing Center Arctic Regional Ocean Observing System Another source of sea ice data is the operational centers that provide support to ships navigating in the Arctic. There are often discrepancies between information from these centers and our data because they employ additional data sources to capture as much detail on sea ice conditions as possible. However, unlike our data, because the quality and availability of their data sources vary, their products do not provide a long-term, consistent timeseries suitable for tracking climate trends and variability. Several Arctic nations have operational sea ice centers. The two North American centers are: US National Ice Center Canadian Ice Service Updated: February 2020 Related questions: Do your data undergo quality control? What is the difference between sea ice area and extent? Return to top Why do different years appear on the graph? Each year at the beginning of January, the reference year on the daily extent graph changes. The graph of daily sea ice extent for the Northern Hemisphere shows ice extent in the current year, the 1981 to 2010 average, and the year with record low ice extent, (currently 2012). The graph has a five month window. This means that in December, the graph shows the record year of 2012, plus some of 2008 (2007-08) and 2013 (2012-13). When we shift the view in January to show five months beginning in October, the graph shows the end of 2006 and the beginning of 2007 (2006-07) and the end of 2011 and the beginning of 2012 (2011-12). July 2013 Return to top What is the standard deviation range on the daily image? In February 2010, we added the range of standard deviation to our daily extent chart. The gray area around the 1981 to 2010 average line shows the two standard deviation range of the data, which serves as an estimate of the expected range of natural variability. For the past few years, Arctic sea ice extent for most months has been more than two standard deviations below the 1981 to 2010 mean, particularly in summer. Updated: July 2013 Related questions: What is standard deviation and how does it relate to sea ice extent? What is the error range for your images? Return to top What is standard deviation and how does it relate to sea ice extent? Standard deviation is a measure of variation around a mean. One standard deviation is defined as encompassing 68% of the variation, and two standard deviations encompass 95% of the variation. Scientists use standard deviations as a way to estimate the range of variability of data. In the context of climate data like sea ice extent, it provides a sense of the range of expected conditions. Measurements that fall far outside of the two standard deviation range or consistently fall outside that range suggest that something unusual is occurring that can’t be explained by normal processes. For sea ice extent data, the standard deviation is computed for each day of the year from the extent on that day over the 30 years of the baseline period, 1981 to 2010. Doubling the standard deviation to produce a 95% range means that 95% of the daily extents for the years 1981 to 2010 fall within that range. In recent years, ice extent has declined and in the summer especially, it has regularly fallen outside of two standard deviations. This suggests that the recent decline in sea ice extent represents a significant change in conditions from 1981 to 2010 time period. Updated: July 2013 Related question: What is the error range for your images? Return to top Why don’t you publish a global sea ice extent number? The combined number, while easy to derive from our online posted data, is not useful as an analysis tool or indicator of climate trends. Looking at each region’s ice extent trends and its processes separately provides more insight into how and why ice extent is changing. Sea ice in the Arctic is governed by somewhat different processes than the sea ice around Antarctica, and the very different geography of the two poles plays a large role. Sea ice in the Arctic exists in a small ocean surrounded by land masses, with greater input of dust, aerosols, and soot than in the Southern Hemisphere. Sea ice in the Southern Hemisphere fringes an ice-covered continent, Antarctica, surrounded by open oceans. While both regions are affected by air, wind, and ocean, the systems and their patterns are inherently very different. Moreover, at any point in time, the two poles are in opposite seasons, and so a combined number would conflate summer and winter trends, or spring and autumn trends, for the two regions. Why is the daily change in sea ice extent in the northern hemisphere larger at the beginning of each month? If you plot the average daily change in sea ice extent in the northern hemisphere, based on the data from ‘Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx,’ you may notice that at the beginning of each month, particularly in the summer, the daily change is larger. This is related to the valid ice masks that are used in the processing of the Sea Ice Index. It is really a land spillover effect: that is, even when there is not ice in a coastal sea, ice can appear to fringe the coast, and fill fjords. This happens because there are mixed land-ocean areas within the sensor’s field of view. That mixture of land and ice looks like sea ice to the algorithms interpreting the sensor data. A correction for land spillover is applied, but it is not perfect. Monthly valid ice masks are also used and these mask out areas where sea ice is not realistic in a given month, including along the coast due to land spillover. When you switch to the next month there is a change in the ice mask. Going from May to June to July, the valid ice mask moves north in the Arctic and crops out more potential ice areas south of the valid ice line. Ice may have receded in a coastal sea by the end of May, for instance, but may still appear to be along the coastline. On the first day of June the new mask removes more of the invalid ice, which is why you see a sudden change in sea ice. Updated: July 2020 Return to top STUDYING SEA ICE What would it mean for Arctic sea ice to recover? Sea ice extent normally varies from year to year, much like the weather changes from day to day. But just as one warm day in October does not negate a cooling trend toward winter, a slight annual gain in sea ice extent over a record low does not negate the long-term decline. Even though the extent of Arctic sea ice has not returned to the record low of 2012, the data show that it is not recovering. To recover would mean returning to within its previous, long-term range. Arctic sea ice extent remains very low. In addition, sea ice remains much thinner than in the past, and so is more vulnerable to further decline. While ice thickness is difficult to measure using satellites, a variety of data sources and estimates indicate that the Arctic ice cover remains thin. For more information on ice thickness, read our Ask a Scientist article, Getting beneath the ice. So what would scientists call a recovery in sea ice? First, a true recovery would continue over a period of multiple years. Second, scientists would expect to see a series of minimum sea ice extents that not only exceed the previous year, but also return to within the range of natural variation. In a recovery, scientists would also expect to see a return to an Arctic sea ice cover dominated by thicker, multiyear ice. Updated: September 2013 Return to top What was sea ice like before the satellite era? The satellite record only dates back to 1979. However, scientists have used historical records of sea ice conditions to estimate sea ice extent before 1979. For more on this topic, read the Ask a Scientist article, How was Arctic sea ice measured before the satellite era? Updated: February 2022 Related questions: Has the Arctic Ocean always had ice in summer? Return to top Has the Arctic Ocean always had ice in summer? We know for sure that at least in the distant past, the Arctic was ice-free. Fossils from the age of the dinosaurs, 65 million years ago, indicate a temperate climate with ferns and other lush vegetation. Based on the paleoclimate record from ice and ocean cores, the last warm period in the Arctic peaked about 8,000 years ago, during the so-called Holocene Thermal Maximum. Some studies suggest that as recent as 5,500 years ago, the Arctic had less summertime sea ice than today. However, it is not clear that the Arctic was completely free of summertime sea ice during this time. The next earliest era when the Arctic was quite possibly free of summertime ice was 125,000 years ago, during the height of the last major interglacial period, known as the Eemian. Temperatures in the Arctic were higher than now and sea level was also 4 to 6 meters (13 to 20 feet) higher than it is today because the Greenland and Antarctic ice sheets had partly melted. Because of the burning of fossil fuels, global averaged temperatures today are getting close to the maximum warmth seen during the Eemian. Carbon dioxide levels now are far above the highest levels during the Eemian, indicating there is still warming to come. According to analyses at NASA and NOAA, the past decade has been the warmest in the observational record dating back to the 19th century and the Arctic has been substantially higher than the global average. Updated: February 2012 Related question: How do we know human activities cause global climate change? Return to top Will the ice at the North Pole melt? Sometimes in everyday use, people associate “the North Pole” with the entire Arctic region. However, when scientists discuss the North Pole, they mean the geographic North Pole, a single point on the globe located at 90 degrees North. The term Arctic generally refers to a much larger region that encompasses the northern latitudes of the globe. The Arctic includes regions of Russia, North America, and Greenland, as well as the Arctic Ocean. The scientific community has a range of predictions concerning when we could see an ice-free Arctic Ocean in summer. Predictions range from sometime between 2030 and 2100. Updated: January 2012 Related questions: What is the gray circle in the middle of some of the extent maps? How will we know if ice at the North Pole melts? Return to top Why don’t I hear much about Antarctic sea ice? NSIDC scientists do monitor sea ice in the Antarctic, and sea ice in the Antarctic is of interest to scientists worldwide. While there are many peer-reviewed journal articles on the topic of Antarctic sea ice and its changes, it has received less attention than the Arctic. Antarctic sea ice has in general changed far less dramatically than Arctic ice. Moreover, changes in Antarctic sea ice are unlikely to have a significant direct impact on the temperate southern latitudes. For more information on Antarctic sea ice, read the Ask a Scientist article, How does Antarctic sea ice differ from Arctic sea ice? Antarctic sea ice data is available on the NSIDC Sea Ice Index. Updated: January 2012 Return to top Is wintertime Antarctic sea ice increasing or decreasing? Wintertime Antarctic sea ice is increasing at a small rate and with substantial year-to-year variation. Monthly sea ice data show trends of increasing sea ice extent that are slightly above the mean year-to-year variability over the satellite record (1979 to present). In more technical terms, the trends are statistically significant at the 95% level, although small (~1% per decade as of 2016). Global climate model projections for sea ice trends around Antarctica are at odds with what is being observed. Nearly all models to date project a slight decline in sea ice extent at present and for the next several decades. The mismatch between model results and observations is a topic of research, and a basis for investigations to find the processes that must be added to the models to align them with what is observed. However, analysis of the variability of Antarctic sea ice in models shows that it is possible that the current trend of increasing sea ice extent is a result of the high variability in the Antarctic sea ice and climate system. The dominant, though subtle, change in the climate pattern of Antarctica has been a gradual increase in the westerly circumpolar winds. Models suggest that both the loss of ozone (the ozone hole that occurs in September/October every year) and increases in greenhouse gases lead to an increase in frequency of this climate pattern. When winds push on sea ice, they tend to move it in the direction they are blowing, but the Coriolis effect adds an apparent push to the left. In the unconfined system of Antarctic sea ice, this pushes the ice northward away from the continent. By spreading sea ice westward and a little northward (and since we measure extent with a 15% cutoff) the gradual trend towards faster mean winds means a gradual trend toward spreading of the ice cover. This general pattern may be part of the explanation for the trend. Recent records of wintertime extents (in 2012, 2013, and 2014) appear to be associated with patterns in air circulation related to the westerly wind regime. The Amundsen Sea Low (ASL), a climate feature of the annual average pressure pattern for Antarctica, varies in both strength and location on a seasonal basis. The ASL tends to be stronger when westerly winds are strong. The ASL, and its effect of sea ice formation and drift, appears to be a major part of the recent string of record winter maximums. More recently (since July 2015) sea ice has returned to near-average conditions, and as of this writing is at a record daily low extent. This highlights the inherent variability in the system. However, one analysis that has attempted to explain both the very large winter extents of 2012, 2013, and 2014, and the subsequent lower and near-average winter maximums in 2015 and 2016 has suggested that the El Niño Southern Oscillation and a Pacific trend called the Pacific Decadal Oscillation (a residual tendency toward El Niño or La Niña in the Pacific that shifts on multi-decadal timescales) may be linked to the change. In other words, the advent of a strong El Niño in late 2015 and early 2016 may have shifted wind and ocean circulation to favor lower extents after a series of La-Niña-prone years (Meehl, 2016). The trend towards stronger circumpolar winds has also caused a sea ice extent decline near the Antarctic Peninsula. In general, the winds tend to dive slightly southward as they approach the Peninsula, an effect of the mountain ridges of the Andes and other circulation features in the Amundsen and Bellingshausen Sea (the ASL mentioned above). A stronger wind from the northwest brings warmer conditions and therefore less ice to the region. Lastly, the El Niño and La Niña cycle also appear to influence sea ice in the Pacific sector. El Niño patterns (a warm eastern tropical Pacific) are associated with warmer winds and less ice; the opposite is true for La Niña. Climate models suggest that the observed increases in Antarctic sea ice are not outside natural variability. However, all models indicate that the ice extent should decrease as greenhouse gases in the atmosphere increase further later in this century. For more information, read the Ask a Scientist article, How does Antarctic sea ice differ from Arctic sea ice? To see data on Antarctic sea ice, see the Sea Ice Index. Updated: December 2016 Related questions: Has the Arctic Ocean always had ice in summer? Return to top CAUSES OF GLOBAL CLIMATE CHANGE AND ICE DECLINE How do we know human activities cause climate change? Fossil fuel burning is responsible for climate change because of the way in which an increased concentration of carbon dioxide in the atmosphere alters the planet’s energy budget and makes the surface warmer. The most fundamental measure of Earth’s climate state is the globally averaged surface air temperature. We define climate change as an extended trend in this temperature. Such a change cannot happen unless something forces the change. Various natural climate forcings exist. For example, periodic changes in the Earth’s orbit about the sun alter the seasonal and latitudinal distribution of solar radiation at the planet’s surface; such variations can be linked to Earth’s ice ages over the past two million years. Changes in solar output influence how much of the sun’s energy the Earth’s surface receives as a whole; more or less solar energy means warmer or cooler global climate. Explosive volcanic eruptions inject sulfur dioxide and dust high into the stratosphere, blocking some of the sun’s energy from reaching the surface and causing it to cool. These are climate forcings because they alter the planet’s radiation or energy budget. An increase in the atmosphere’s concentration of carbon dioxide is also a climate forcing: it leads to a situation in which the planet absorbs more solar radiation than it emits to space as longwave radiation. This means the system gains energy. The globally averaged temperature will increase as a result. This is in accord with a fundamental principle of physics: conservation of energy. As humans burn fossil fuels, adding carbon dioxide to the atmosphere, globally average temperature rises as a result. Arctic Sea Ice 6th Lowest on Record; Antarctic Sees Record Low GrowthIn Brief:The annual Arctic sea ice minimum (lowest) annual extent was the sixth-lowest on record this year, while Antarctic sea ice reached its lowest maximum ever. These both continue a long-term downward trend due to human-caused global warming.Arctic sea ice likely reached its annual minimum extent on Sept. 19, 2023, making it the sixth-lowest year in the satellite record, according to researchers at NASA and the National Snow and Ice Data Center (NSIDC). Meanwhile, Antarctic sea ice reached its lowest maximum extent on record on Sept. 10 at a time when the ice cover should have been growing at a much faster pace during the darkest and coldest months.Scientists track the seasonal and annual fluctuations because sea ice shapes Earth’s polar ecosystems and plays a significant role in global climate. Researchers at NSIDC and NASA use satellites to measure sea ice as it melts and refreezes. They track sea ice extent, which is defined as the total area of the ocean in which the ice cover fraction is at least 15%.Between March and September 2023, the ice cover in the Arctic shrank from a peak area of 5.64 million square miles (14.62 million square kilometers) to 1.63 million square miles (4.23 million square kilometers). That’s roughly 770,000 square miles (1.99 million square kilometers) below the 1981–2010 average minimum of 2.4 million square miles (6.22 million square kilometers). The amount of sea ice lost was enough to cover the entire continental United States.Sea ice around Antarctica reached its lowest winter maximum extent on Sept. 10, 2023, at 6.5 million square miles (16.96 million square kilometers). That’s 398,000 square miles (1.03 million square kilometers) below the previous record-low reached in 1986 – a difference that equates to roughly the size of Texas and California combined. The average maximum extent between 1981 and 2010 was 7.22 million square miles (18.71 million square kilometers).“It’s a record-smashing sea ice low in the Antarctic,” said Walt Meier, a sea ice scientist at NSIDC. “Sea ice growth appears low around nearly the whole continent as opposed to any one region.”This year in the Arctic, scientists saw notably low levels of ice in the Northwest Passage, Meier added. “It is more open there than it used to be. There also seems to be a lot more loose, lower concentration ice – even toward the North Pole – and areas that used to be pretty compact, solid sheets of ice through the summer. That’s been happening more frequently in recent years.”Meier said the changes are a fundamental, decades-long response to warming temperatures. Since the start of the satellite record for ice in 1979, sea ice has not only been declining in the Arctic, but also getting younger. Earlier starts to spring melting and ever-later starts to autumn freeze-up are leading to longer melting seasons. Research has shown that, averaged across the entire Arctic Ocean, freeze-up is happening about a week later per decade, or one month later than in 1979.Nathan Kurtz, lab chief of NASA’s Cryospheric Sciences Laboratory at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, said that as the Arctic warms about four times faster than the rest of the planet, the ice is also growing thinner. “Thickness at the end of the growth season largely determines the survivability of sea ice. New research is using satellites like NASA’s ICESat-2 (Ice, Cloud and land Elevation Satellite-2) to monitor how thick the ice is year-round.”Kurtz said that long-term measurements of sea ice are critical to studying what’s happening in real time at the poles. “At NASA we’re interested in taking cutting-edge measurements, but we’re also trying to connect them to the historical record to better understand what’s driving some of these changes that we’re seeing.”Scientists are working to understand the cause of the meager growth of the Antarctic sea ice, which could include a combination of factors such as El Nino, wind patterns, and warming ocean temperatures. New research has shown that ocean heat is likely playing an important role in slowing cold season ice growth and enhancing warm season melting.This record-low extent so far in 2023 is a continuation of a downward trend in Antarctic sea ice that started after a record high in 2014. Prior to 2014, ice surrounding the continent was increasing slightly by about 1% per decade.Sea ice melting at both poles reinforces warming because of a cycle called “ice-albedo feedback.” While bright sea ice reflects most of the Sun’s energy back to space, open ocean water absorbs 90% of it. With greater areas of the ocean exposed to solar energy, more heat can be absorbed, which warms the ocean waters and further delays sea ice growth. +Global climate change is not a future problem. Changes to Earth’s climate driven by increased human +emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: +glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic +ranges are shifting, and plants and trees are blooming sooner. + +Effects that scientists had long predicted would result from global climate change are now occurring, +such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves. + +Some changes (such as droughts, wildfires, and extreme rainfall) +are happening faster than scientists previously assessed. In fact, +according to the Intergovernmental Panel on Climate Change (IPCC) — the United Nations +body established to assess the science related to climate change — modern humans have +never before seen the observed changes in our global climate, and some of these changes +are irreversible over the next hundreds to thousands of years. + +Scientists have high confidence that global temperatures will continue to rise +for many decades, mainly due to greenhouse gases produced by human activities + +The IPCC’s Sixth Assessment report, published in 2021, found that human +emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit +(1.1 degrees Celsius) since 1850-1900.1 The global average temperature is expected to reach or +exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth. + +The severity of effects caused by climate change will depend on the path of future human activities. +More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects +across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. +So, if we can reduce emissions, we may avoid some of the worst effects. + +What’s the difference between climate change and global warming? + +The terms “global warming” and “climate change” are sometimes used interchangeably, but "global warming" is only one aspect of climate change. + +“Global warming” refers to the long-term warming of the planet. Global temperature shows a +well-documented rise since the early 20th century and most notably since the late 1970s. +Worldwide since 1880, the average surface temperature has risen about 1°C (about 2°F), relative to +the mid-20th century baseline (of 1951-1980). This is on top of about an additional 0.15°C of +warming from between 1750 and 1880. + +“Climate change” encompasses global warming, but refers to the broader range of changes that are +happening to our planet. These include rising sea levels; shrinking mountain glaciers; accelerating +ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times. +These are all consequences of warming, which is caused mainly by people burning fossil fuels +and putting out heat-trapping gases into the air. + +Global temperature rise from 1880 to 2022. Higher-than-normal +temperatures are shown in red and lower-than-normal temperatures are shown in blue. +Each frame represents global temperature anomalies (changes) averaged over the five years +previous to that particular year. Credit: NASA Goddard Space Flight Center/NASA Scientific +Visualization Studio/NASA Goddard Institute for Space Studies. + +What Is Climate Change? + +Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, +regional and global climates. These changes have a broad range of observed effects that are synonymous with the term. + +Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly +fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth’s atmosphere, raising Earth’s +average surface temperature. Natural processes, which have been overwhelmed by human activities, can also contribute +to climate change, including internal variability (e.g., cyclical ocean patterns like El Niño, La Niña and the Pacific +Decadal Oscillation) and external forcings (e.g., volcanic activity, changes in the Sun’s energy output, variations in Earth’s orbit). + +Scientists use observations from the ground, air, and space, along with computer models, to monitor and study +past, present, and future climate change. Climate data records provide evidence of climate change key indicators, +such as global land and ocean temperature increases; rising sea levels; ice loss at Earth’s poles and in mountain +glaciers; frequency and severity changes in extreme weather such as hurricanes, heatwaves, wildfires, droughts, +floods, and precipitation; and cloud and vegetation cover changes. + +“Climate change” and “global warming” are often used interchangeably but have distinct meanings. Similarly, the +terms "weather" and "climate" are sometimes confused, though they refer to events with broadly different +spatial- and timescales. + +What Is Global Warming? + +Global warming is the long-term heating of Earth’s surface observed since the pre-industrial period +(between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases +heat-trapping greenhouse gas levels in Earth’s atmosphere. This term is not interchangeable with the term "climate change." + +Since the pre-industrial period, human activities are estimated to have increased Earth’s global +average temperature by about 1 degree Celsius (1.8 degrees Fahrenheit), a number that is currently +increasing by more than 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade. The current warming +trend is unequivocally the result of human activity since the 1950s and is proceeding at +an unprecedented rate over millennia. + +Weather refers to atmospheric conditions that occur locally over short periods of time—from +minutes to hours or days. Familiar examples include rain, snow, clouds, winds, floods, or thunderstorms. + +Climate, on the other hand, refers to the long-term (usually at least 30 years) regional or +even global average of temperature, humidity, and rainfall patterns over seasons, years, or +decades. + +The Causes of Climate Change + +Four Major Gases That Contribute to the Greenhouse Effect: + +FORCING: Something acting upon Earth's climate that causes a change in how energy flows +through it (such as long-lasting, heat-trapping gases - also known as greenhouse gases). +These gases slow outgoing heat in the atmosphere and cause the planet to warm. + +Carbon Dioxide +A very important component of the atmosphere, carbon dioxide (CO2) +is released through natural processes (like volcanic eruptions) and through +human activities, like burning fossil fuels and deforestation. +Human activities have increased the amount of CO2 in the atmosphere by 50% since the +Industrial Revolution began (1750). This sharp rise in CO2 is the most important +climate change driver over the last century. + +Methane +Like many atmospheric gases, methane comes from both natural and human-caused sources. +Methane comes from plant-matter breakdown in wetlands and is also released from landfills +and rice farming. Livestock animals emit methane from their digestion and manure. +Leaks from fossil fuel production and transportation are another major source of methane, +and natural gas is 70% to 90% methane. As a single molecule, methane is a far more effective +greenhouse gas than carbon dioxide but is much less common in the atmosphere. The amount of +methane in our atmosphere has more than doubled since pre-industrial times. + +Nitrous Oxide +A potent greenhouse gas produced by farming practices, nitrous oxide is released during +commercial and organic fertilizer production and use. Nitrous oxide also +comes from burning fossil fuels and burning vegetation and has increased +by 18% in the last 100 years. + +Chlorofluorocarbons (CFCs) +These chemical compounds do not exist in nature – they are entirely of industrial origin. They were used as refrigerants, +solvents (a substance that dissolves others), and spray-can propellants. An international agreement, +known as the Montreal Protocol, now regulates CFCs because they damage the ozone layer. Despite this, +emissions of some types of CFCs spiked for about five years due to violations of the international agreement. +Once members of the agreement called for immediate action and better enforcement, emissions dropped sharply starting in 2018. + +Another Gas That Contributes to the Greenhouse Effect: + +Water Vapor +Water vapor is the most abundant greenhouse gas, +but because the warming ocean increases the amount of it in our atmosphere, +it is not a direct cause of climate change. Rather, as other forcings (like carbon dioxide) +change global temperatures, water vapor in the atmosphere responds, amplifying climate change +already in motion. Water vapor increases as Earth's climate warms. Clouds and precipitation +(rain or snow) also respond to temperature changes and can be important feedback mechanisms as well. + +Human Activity Is the Cause of Increased Greenhouse Gas Concentrations +Over the last century, burning of fossil fuels like coal and oil has increased the concentration of +atmospheric carbon dioxide (CO2). This increase happens because the coal or oil burning process +combines carbon with oxygen in the air to make CO2. To a lesser extent, clearing of land for agriculture, +industry, and other human activities has increased concentrations of greenhouse gases. + +How do we know what greenhouse gas and temperature levels were in the distant past? +The industrial activities that our modern civilization depends upon have raised atmospheric +carbon dioxide levels by nearly 50% since 17502. This increase is due to human activities, because +scientists can see a distinctive isotopic fingerprint in the atmosphere. + +In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of +scientific experts from countries all over the world, concluded that it is unequivocal that +the increase of CO2, methane, and nitrous oxide in the atmosphere over the industrial era is +the result of human activities and that human influence is the principal driver of many changes +observed across the atmosphere, ocean, cryosphere and biosphere. + +How do we know what greenhouse gas and temperature levels were in the distant past? + +Ice cores are scientists’ best source for historical climate data. Every winter, some snow coating Arctic +and Antarctic ice sheets is left behind and compressed into a layer of ice. By extracting cylinders of ice +from sheets thousands of meters thick, scientists can analyze dust, ash, pollen and bubbles of atmospheric +gas trapped inside. The deepest discovered ice cores are an estimated 800,000 years old. The particles trapped +inside give scientists clues about volcanic eruptions, desert extent and forest fires. The presence of certain +ions indicates past ocean activity, levels of sea ice and even the intensity of the Sun. The bubbles can be +released to reveal the make-up of the ancient atmosphere, including greenhouse gas levels. + +Other tools for learning about Earth’s ancient atmosphere include growth rings in trees, +which keep a rough record of each growing season’s temperature, moisture and cloudiness +going back about 2,000 years. Corals also form growth rings that provide information about +temperature and nutrients in the tropical ocean. Other proxies, such as benthic cores, +extend our knowledge of past climate back about a billion years. + +Evidence Shows That Current Global Warming Cannot Be Explained by Solar Irradiance +Scientists use a metric called Total Solar Irradiance (TSI) to measure the changes in +energy the Earth receives from the Sun. TSI incorporates the 11-year solar cycle and solar flares/storms from the Sun's surface. + +Studies show that solar variability has played a role in past climate changes. +For example, a decrease in solar activity coupled with increased volcanic activity +helped trigger the Little Ice Age. + +But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun: + +Since 1750, the average amount of energy from the Sun either remained constant or decreased slightly3. +If a more active Sun caused the warming, scientists would expect warmer temperatures +in all layers of the atmosphere. Instead, they have observed a cooling in the upper +tmosphere and a warming at the surface and lower parts of the atmosphere. +That's because greenhouse gases are slowing heat loss from the lower atmosphere. +Climate models that include solar irradiance changes can’t reproduce the observed +temperature trend over the past century or more without including a rise in greenhouse gases. + +What Is Climate Change? +Climate change describes a change in the average conditions — such as temperature and rainfall — +in a region over a long period of time. NASA scientists have observed Earth’s surface is warming, +and many of the warmest years on record have happened in the past 20 years. + +Weather describes the conditions outside right now in a specific place. For example, +if you see that it’s raining outside right now, that’s a way to describe today’s weather. +Rain, snow, wind, hurricanes, tornadoes — these are all weather events. + +Climate, on the other hand, is more than just one or two rainy days. Climate describes the +weather conditions that are expected in a region at a particular time of year. + +Is it usually rainy or usually dry? Is it typically hot or typically cold? A region’s climate is +determined by observing its weather over a period of many years—generally 30 years or more. + +So, for example, one or two weeks of rainy weather wouldn’t change the fact that Phoenix typically +has a dry, desert climate. Even though it’s rainy right now, we still expect Phoenix to be dry +because that's what is usually the case. + +Climate change describes a change in the average conditions — such as temperature and rainfall — in a +region over a long period of time. For example, 20,000 years ago, much of the United States was covered in +glaciers. In the United States today, we have a warmer climate and fewer glaciers. + +Global climate change refers to the average long-term changes over the entire Earth. These include warming +temperatures and changes in precipitation, as well as the effects of Earth’s warming, such as: + +Rising sea levels +Shrinking mountain glaciers +Ice melting at a faster rate than usual in Greenland, Antarctica and the Arctic +Changes in flower and plant blooming times. + +Earth’s climate has constantly been changing — even long before humans came into the picture. However, scientists +have observed unusual changes recently. For example, Earth’s average temperature has been increasing much more +quickly than they would expect over the past 150 years. + +How Much Is Earth’s Climate Changing Right Now? + +Some parts of Earth are warming faster than others. But on average, global air temperatures near +Earth's surface have gone up about 2 degrees Fahrenheit in the past 100 years. In fact, the past five +years have been the warmest five years in centuries. + +Many people, including scientists, are concerned about this warming. As Earth’s climate continues to warm, +the intensity and amount of rainfall during storms such as hurricanes is expected to increase. +Droughts and heat waves are also expected to become more intense as the climate warms. + +When the whole Earth’s temperature changes by one or two degrees, that change can have big +impacts on the health of Earth's plants and animals, too. + +There are lots of factors that contribute to Earth’s climate. However, scientists agree that Earth has been +getting warmer in the past 50 to 100 years due to human activities. + +Certain gases in Earth’s atmosphere block heat from escaping. This is called the greenhouse effect. These gases +keep Earth warm like the glass in a greenhouse keeps plants warm. + +Human activities — such as burning fuel to power factories, cars and buses — are changing the natural greenhouse. +These changes cause the atmosphere to trap more heat than it used to, leading to a warmer Earth. + +What are greenhouse gases? +Greenhouse gases are gases in Earth’s atmosphere that trap heat. +They let sunlight pass through the atmosphere, but they prevent the heat that the sunlight brings from leaving +the atmosphere. The main greenhouse gases are: + +Water vapor +Carbon dioxide +Methane +Ozone +Nitrous oxide +Chlorofluorocarbons + +Greenhouse gases are gases that can trap heat. They get their name from greenhouses. +A greenhouse is full of windows that let in sunlight. That sunlight creates warmth. +The big trick of a greenhouse is that it doesn’t let that warmth escape. + +That’s exactly how greenhouse gases act. They let sunlight pass through the atmosphere, +but they prevent the heat that the sunlight brings from leaving the atmosphere. Overall, +greenhouse gases are a good thing. Without them, our planet would be too cold, and life as +we know it would not exist. But there can be too much of a good thing. Scientists are worried +that human activities are adding too much of these gases to the atmosphere. + +How Do We Know Climate Change Is Real? +While Earth’s climate has changed throughout its history, the +current warming is happening at a rate not seen in the past 10,000 years. + +According to the Intergovernmental Panel on Climate Change (IPCC), +"Since systematic scientific assessments began in the 1970s, the influence +of human activity on the warming of the climate system has evolved from theory to established fact."1 + +Scientific information taken from natural sources (such as ice cores, rocks, and tree rings) +and from modern equipment (like satellites and instruments) all show the signs of a changing climate. + +From global temperature rise to melting ice sheets, the evidence of a warming planet abounds. + +The rate of change since the mid-20th century is unprecedented over millennia. +Earth's climate has changed throughout history. Just in the last 800,000 years, there have been eight +cycles of ice ages and warmer periods, with the end of the last ice age about 11,700 years +ago marking the beginning of the modern climate era — and of human civilization. Most of +these climate changes are attributed to very small variations in Earth’s orbit that change +the amount of solar energy our planet receives. + +The current warming trend is different because it is clearly the result of +human activities since the mid-1800s, and is proceeding at a rate not seen over +many recent millennia.1 It is undeniable that human activities have produced the atmospheric +gases that have trapped more of the Sun’s energy in the Earth system. This extra energy has warmed +the atmosphere, ocean, and land, and widespread and rapid changes in the atmosphere, ocean, cryosphere, +and biosphere have occurred. + +Ice cores drawn from Greenland, Antarctica, and tropical mountain +glaciers show that Earth’s climate responds to changes in greenhouse gas +levels. Ancient evidence can also be found in tree rings, ocean sediments, +coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that +current warming is occurring roughly 10 times faster than the average rate of warming after an ice age. +Carbon dioxide from human activities is increasing about 250 times faster than it did from natural +sources after the last Ice Age. + +Do scientists agree on climate change? + +Earth-orbiting satellites and new technologies +have helped scientists see the big picture, collecting many different types of information +about our planet and its climate all over the world. These data, collected over many years, +reveal the signs and patterns of a changing climate. + +Scientists demonstrated the heat-trapping nature of carbon dioxide and other gases in the mid-19th +century.2 Many of the science instruments NASA uses to study our climate focus on how these gases +affect the movement of infrared radiation through the atmosphere. From the measured impacts of +increases in these gases, there is no question that increased greenhouse gas levels warm Earth in +response. + +The Evidence for Rapid Climate Change Is Compelling: + +Global Temperature Is Rising +The planet's average surface temperature has risen about degrees Fahrenheit (1 degrees Celsius) +since the late 19th century, a change driven largely by increased carbon dioxide emissions into +the atmosphere and other human activities.4 Most of the warming occurred in the past 40 years, +with the seven most recent years being the warmest. The years 2016 and 2020 are tied for the +warmest year on record. + +The Ocean Is Getting Warmer +The ocean has absorbed much of this increased heat, +with the top 100 meters (about 328 feet) of ocean showing warming of 0.67 degrees Fahrenheit +(0.33 degrees Celsius) since 1969.6 Earth stores 90% of the extra energy +in the ocean. + +Glaciers Are Retreating +Glaciers are retreating almost everywhere around the world — +including in the Alps, Himalayas, Andes, Rockies, Alaska, +and Africa. + +The Ice Sheets Are Shrinking +The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA's Gravity Recovery +and Climate Experiment show Greenland lost an average of 279 billion tons of ice per year between +1993 and 2019, while Antarctica lost about 148 billion tons of ice per year.7 Image: The Antarctic Peninsula, Credit: NASA + +Snow Cover Is Decreasing +Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has +decreased over the past five decades and the snow is melting earlier + +Sea Level Is Rising +Global sea level rose about 8 inches (20 centimeters) in the last century. +The rate in the last two decades, however, is nearly double that of the last century and accelerating slightly every year + +Arctic Sea Ice Is Declining +Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades. + +Extreme Events Are Increasing in Frequency +The number of record high temperature events in the United States has been increasing, +while the number of record low temperature events has been decreasing, since 1950. +The U.S. has also witnessed increasing numbers of intense rainfall events. + +Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has +increased by about 30%.13,14 This increase is due to humans emitting more +carbon dioxide into the atmosphere and hence more being absorbed into the ocean. +The ocean has absorbed between 20% and 30% of total anthropogenic carbon dioxide emissions +in recent decades (7.2 to 10.8 billion metric tons per year). + +SolimĂ”es and Negro Rivers +The largest river on the planet, the Amazon, forms from the confluence of the +SolimĂ”es (the upper Amazon River) and the Negro at the Brazilian city of Manaus in central Amazonas. +At the river conjunction, the muddy, tan-colored waters of the SolimĂ”es meet the “black” water of +the Negro River. The unique mixing zone where the waters meet extends downstream through the rainforest +for hundreds of miles, and attracts tourists from all over the world, which has contributed to substantial +growth in the city of Manaus. + +It is the vast quantity of sediment eroded from the Andes Mountains that gives +the SolimĂ”es its tan color. By comparison, water in the Negro derives from the +low jungles where reduced physical erosion of rock precludes mud entering the river. +In place of sediment, organic matter from the forest floor stains the river the color of black tea. + +The SolimĂ”es provides nutrient-rich mud to lakes on the floodplain (lower right). +The ecology of muddy lakes differs correspondingly from that of nutrient-poor, +blackwater rivers and lakes. SolimĂ”es water can be seen leaking into the Negro west of the main +meeting zone (lower left). The SolimĂ”es is much shallower than the Negro because it has +filled its valley and bed with great quantities of sediment since the valleys were excavated. + +NASA is an expert in climate and Earth science. While its role is not to set climate policy or prescribe particular responses or solutions to climate change, its job does include providing the scientific data needed to understand climate change. NASA then makes this information available to the global community – the public, policy-, and decision-makers and scientific and planning agencies around the world. (For more information, see NASA's role.) + +With that said, NASA takes sustainability very seriously. NASA’s sustainability policy is to execute its mission as efficiently as possible. In doing so, we continually improve our space and ground operations. + +Sustainability involves taking action now to protect the environment for both current and future living conditions. In implementing sustainability practices, NASA supports its missions by reducing risks to the environment and our communities. + +In executing its mission, NASA's sustainability objectives are to: + +increase energy efficiency; + +increase the use of renewable energy; + +measure, report, and reduce NASA's direct and indirect greenhouse gas emissions; + +conserve and protect water resources through efficiency, reuse, and stormwater management; + +eliminate waste, prevent pollution, and increase recycling; + +leverage agency acquisitions to foster markets for sustainable technologies and environmentally preferable materials, products, and services; + +design, construct, maintain, and operate high-performance sustainable buildings; + +utilize power management options and reduce the number of agency data centers; + +support economic growth and livability of the communities where NASA conducts business; +evaluate agency climate change risks and vulnerabilities and develop mitigation and +adaptation measures to manage both the short-and long-term effects of climate change on the agency's mission and operations; + +raise employee awareness and encourage each individual in the NASA community to apply + ]the concepts of sustainability to every aspect of their daily work to achieve these goals; + +maintain compliance with all applicable federal, state, local or territorial law and regulations related to energy security, a +healthy environment, and environmentally-sound operations; +and comply with internal NASA requirements and agreements with other entities. + +One of the wettest wet seasons in northern Australia transformed + +large areas of the country’s desert landscape over the course of many months in 2023. A string +of major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and +April 2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color +images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water +appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired + +by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between +January and July 2023.In the January 22 image (left), water was coursing through seasonally +dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern +Queensland. By April 21 (middle), floodwaters had reached further downstream after another +intense period of precipitation in March. This scene shows that water had filled in some of + +the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed +dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed +had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately +210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible +in the lower part of the images, the lake gets refreshed about every three years; when it + +reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring +lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of +thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is +a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy +season stood out in several ways. They occurred while La Niña conditions were in place over + +the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during +La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring +in succession, as was the case with the January and March events, have the overall effect +of prolonging floods. That’s because vegetation that grows after the first event slows down +the pulse of water that comes through in the next rain event.The high water has affected both + +local communities and ecosystems. Floods have inundated cattle farms and isolated towns on +temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology +of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory +image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by +Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves + +of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day +Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave +a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water +Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the +Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images + +show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods +January 22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed +large areas of the country’s desert landscape over the course of many months in 2023. A string +of major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and +April 2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color + +images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water +appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired +by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between +January and July 2023.In the January 22 image (left), water was coursing through seasonally +dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern + +Queensland. By April 21 (middle), floodwaters had reached further downstream after another +intense period of precipitation in March. This scene shows that water had filled in some of +the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed +dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed +had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately + +210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible +in the lower part of the images, the lake gets refreshed about every three years; when it +reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring +lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of +thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is + +a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy +season stood out in several ways. They occurred while La Niña conditions were in place over +the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during +La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring +in succession, as was the case with the January and March events, have the overall effect + +of prolonging floods. That’s because vegetation that grows after the first event slows down +the pulse of water that comes through in the next rain event.The high water has affected both +local communities and ecosystems. Floods have inundated cattle farms and isolated towns on +temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology +of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory + +image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by +Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves +of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day +Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave +a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water + +Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the +Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images +show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods +August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated + +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams + +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks + +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the + +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. + +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers + +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours + +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence January 22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia +transformed large areas of the country’s desert landscape over the course of many months in +2023. A string of major rainfall events that dropped 690 millimeters (27 inches) between October +2022 and April 2023 made it the sixth-wettest season on record since 1900–1901.This series + +of false-color images illustrates the rainfall’s months-long effects downstream in the Lake +Eyre Basin. Water appears in shades of blue, vegetation is green, and bare land is brown. +The images were acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s +Terra satellite between January and July 2023.In the January 22 image (left), water was coursing +through seasonally dry channels of the Georgina River and Eyre Creek following weeks of heavy + +rains in northern Queensland. By April 21 (middle), floodwaters had reached further downstream +after another intense period of precipitation in March. This scene shows that water had filled +in some of the north-northwest trending ridges that are part of a vast fossil landscape of +wind-formed dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), +the riverbed had filled with even more vegetation.The Georgina River and Eyre Creek drain + +approximately 210,000 square kilometers (81,000 square miles), nearly the area of the United +Kingdom. Visible in the lower part of the images, the lake gets refreshed about every three +years; when it reaches especially high levels, it may take 18 months to 2 years to dry up. +Two smaller neighboring lakes flood seasonally. These three lakes and surrounding floodplains +support hundreds of thousands of waterbirds and are designated as an Important Bird Area.Seasonal + +flooding is a regular occurrence in these desert river systems. However, the events of the +2022-2023 rainy season stood out in several ways. They occurred while La Niña conditions were +in place over the tropical Pacific Ocean. (The wettest seasons in northern Australia have +all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) In addition, +major rains occurring in succession, as was the case with the January and March events, have + +the overall effect of prolonging floods. That’s because vegetation that grows after the first +event slows down the pulse of water that comes through in the next rain event.The high water +has affected both local communities and ecosystems. Floods have inundated cattle farms and +isolated towns on temporary islands. At the same time, they are a natural feature of the “boom-and-bust” +ecology of Channel Country, providing habitat and nutrients that support biodiversity.NASA + +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set +off waves of new growth across Channel Country.Image of the Day for August 7, 2023 Image of +the Day Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o +can heave a crushing amount of water toward the shore and onto unlucky surfers. Image of the + +Day Water Waves of heavy rainfall left towns and farmland under water in October 2022. Image +of the Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color +images show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land +Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, +2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean + +inundated cities along the northeastern coast of Libya in early September 2023, causing thousands +of deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams + +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks + +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the + +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. + +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers + +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours + +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational + +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color + +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in + +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. + +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered + +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability + +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from + +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean + +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the + +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level + +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence January 22 - July 26, +2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of the +country’s desert landscape over the course of many months in 2023. A string of major rainfall + +events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it +the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates +the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades +of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and + +July 2023.In the January 22 image (left), water was coursing through seasonally dry channels +of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. +By April 21 (middle), floodwaters had reached further downstream after another intense period +of precipitation in March. This scene shows that water had filled in some of the north-northwest +trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation + +had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even +more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers +(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of +the images, the lake gets refreshed about every three years; when it reaches especially high +levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. + +These three lakes and surrounding floodplains support hundreds of thousands of waterbirds +and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in +these desert river systems. However, the events of the 2022-2023 rainy season stood out in +several ways. They occurred while La Niña conditions were in place over the tropical Pacific +Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, + +according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, +as was the case with the January and March events, have the overall effect of prolonging floods. +That’s because vegetation that grows after the first event slows down the pulse of water that +comes through in the next rain event.The high water has affected both local communities and +ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At + +the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, +providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by +Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey +Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new +growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water + +View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing +amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of +heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water +Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the +impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August + +25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over + +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. + +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate + +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest + +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 + +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm + +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color + +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the + +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with + +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s + +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the + +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had + +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, + +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming + +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) + +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image + +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe + +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities + +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks + +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely + +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite + +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility + +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary + +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze January 22 +- July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large +areas of the country’s desert landscape over the course of many months in 2023. A string of + +major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and April +2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color +images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water +appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired +by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between + +January and July 2023.In the January 22 image (left), water was coursing through seasonally +dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern +Queensland. By April 21 (middle), floodwaters had reached further downstream after another +intense period of precipitation in March. This scene shows that water had filled in some of +the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed + +dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed +had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately +210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible +in the lower part of the images, the lake gets refreshed about every three years; when it +reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring + +lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of +thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is +a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy +season stood out in several ways. They occurred while La Niña conditions were in place over +the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during + +La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring +in succession, as was the case with the January and March events, have the overall effect +of prolonging floods. That’s because vegetation that grows after the first event slows down +the pulse of water that comes through in the next rain event.The high water has affected both +local communities and ecosystems. Floods have inundated cattle farms and isolated towns on + +temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology +of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory +image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by +Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves +of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day + +Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave +a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water +Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the +Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images +show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods + +August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over + +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. + +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate + +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest + +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 + +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm + +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color + +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the + +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with + +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s + +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the + +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had + +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, + +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming + +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) + +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image + +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe + +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities + +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks + +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely + +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite + +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility + +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary + +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, + +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and + +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area + +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story + +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings + +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth + +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere + +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice January 22 - July 26, 2023JPEGOne + +of the wettest wet seasons in northern Australia transformed large areas of the country’s +desert landscape over the course of many months in 2023. A string of major rainfall events +that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it the sixth-wettest +season on record since 1900–1901.This series of false-color images illustrates the rainfall’s +months-long effects downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation + +is green, and bare land is brown. The images were acquired by the Moderate Resolution Imaging +Spectroradiometer (MODIS) on NASA’s Terra satellite between January and July 2023.In the January +22 image (left), water was coursing through seasonally dry channels of the Georgina River +and Eyre Creek following weeks of heavy rains in northern Queensland. By April 21 (middle), +floodwaters had reached further downstream after another intense period of precipitation in + +March. This scene shows that water had filled in some of the north-northwest trending ridges +that are part of a vast fossil landscape of wind-formed dunes, while vegetation had emerged +in wet soil upstream. Then by July 26 (right), the riverbed had filled with even more vegetation.The +Georgina River and Eyre Creek drain approximately 210,000 square kilometers (81,000 square +miles), nearly the area of the United Kingdom. Visible in the lower part of the images, the + +lake gets refreshed about every three years; when it reaches especially high levels, it may +take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. These +three lakes and surrounding floodplains support hundreds of thousands of waterbirds and are +designated as an Important Bird Area.Seasonal flooding is a regular occurrence in these desert +river systems. However, the events of the 2022-2023 rainy season stood out in several ways. + +They occurred while La Niña conditions were in place over the tropical Pacific Ocean. (The +wettest seasons in northern Australia have all occurred during La Niña years, according to +Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, as was +the case with the January and March events, have the overall effect of prolonging floods. +That’s because vegetation that grows after the first event slows down the pulse of water that + +comes through in the next rain event.The high water has affected both local communities and +ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At +the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, +providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by +Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey + +Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new +growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water +View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing +amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of +heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water + +Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the +impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August +25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of + +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland + +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier + +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, + +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological + +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s + +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods + +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected + +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua + +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher + +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown + +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color + +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating + +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough + +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there + +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory + +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image + +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke + +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, + +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, + +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. + +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena + +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands + +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour + +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts + +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the + +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone + +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts + +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported + +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, + +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and + +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters + +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. + +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, + +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how + +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from + +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land + +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for + +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and + +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life January 22 - July +26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of +the country’s desert landscape over the course of many months in 2023. A string of major rainfall +events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it + +the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates +the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades +of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and +July 2023.In the January 22 image (left), water was coursing through seasonally dry channels + +of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. +By April 21 (middle), floodwaters had reached further downstream after another intense period +of precipitation in March. This scene shows that water had filled in some of the north-northwest +trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation +had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even + +more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers +(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of +the images, the lake gets refreshed about every three years; when it reaches especially high +levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. +These three lakes and surrounding floodplains support hundreds of thousands of waterbirds + +and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in +these desert river systems. However, the events of the 2022-2023 rainy season stood out in +several ways. They occurred while La Niña conditions were in place over the tropical Pacific +Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, +according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, + +as was the case with the January and March events, have the overall effect of prolonging floods. +That’s because vegetation that grows after the first event slows down the pulse of water that +comes through in the next rain event.The high water has affected both local communities and +ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At +the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, + +providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by +Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey +Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new +growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water +View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing + +amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of +heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water +Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the +impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August +25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember + +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow + +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired + +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International + +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution + +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting + +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. + +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, + +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has + +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). + +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been + +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far + +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data + +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital + +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. + +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The + +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets + +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate + +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s + +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert + +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined + +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA + +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human + +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land + +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, + +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach + +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during + +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, + +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area + +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story + +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve + +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going + +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered + +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the + +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, + +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can + +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View + +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence + +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. + +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember + +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer +and early fall of 2023. In September, low water levels limited barge shipments downriver and +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 + +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This +is the second year in a row drought has caused the river to fall to near-record lows at many +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That +was the lowest level recorded there since the start of National Weather Service records in + +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they +are measured with respect to a chosen reference point. That is why some gauge height measurements +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. + +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of + +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. + +Lack of precipitation and high temperatures over several months severely dried out soils in +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions +along the river interrupted normal shipments of goods. According to the Associated Press, + +barge companies reduced the weight carried in many shipments in September because the river +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water + +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines +Parish are under drinking water advisories and have relied on bottled water for cooking and +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late + +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 + +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record + +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low +water levels are making it difficult to ship goods down the river and allowing a wedge of +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing January +22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large +areas of the country’s desert landscape over the course of many months in 2023. A string of + +major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and April +2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color +images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water +appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired +by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between + +January and July 2023.In the January 22 image (left), water was coursing through seasonally +dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern +Queensland. By April 21 (middle), floodwaters had reached further downstream after another +intense period of precipitation in March. This scene shows that water had filled in some of +the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed + +dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed +had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately +210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible +in the lower part of the images, the lake gets refreshed about every three years; when it +reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring + +lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of +thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is +a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy +season stood out in several ways. They occurred while La Niña conditions were in place over +the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during + +La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring +in succession, as was the case with the January and March events, have the overall effect +of prolonging floods. That’s because vegetation that grows after the first event slows down +the pulse of water that comes through in the next rain event.The high water has affected both +local communities and ecosystems. Floods have inundated cattle farms and isolated towns on + +temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology +of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory +image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by +Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves +of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day + +Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave +a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water +Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the +Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images +show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods + +August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over + +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. + +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate + +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest + +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 + +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm + +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color + +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the + +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with + +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s + +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the + +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had + +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, + +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming + +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) + +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image + +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe + +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities + +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks + +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely + +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite + +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility + +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary + +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, + +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and + +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area + +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story + +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings + +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth + +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere + +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay + +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 + +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University + +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, + +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome + +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start + +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists + +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late + +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember + +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer +and early fall of 2023. In September, low water levels limited barge shipments downriver and +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the + +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This +is the second year in a row drought has caused the river to fall to near-record lows at many +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That + +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they +are measured with respect to a chosen reference point. That is why some gauge height measurements +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally + +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department + +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring + +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions + +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the + +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines +Parish are under drinking water advisories and have relied on bottled water for cooking and +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast + +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the + +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests + +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low +water levels are making it difficult to ship goods down the river and allowing a wedge of +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced + +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long +lake has a watershed that spans one million square kilometers (386,000 square miles), draining +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September + +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients + +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents + +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between + +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous +to the lake were increased agricultural activities in the watershed and a higher frequency +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 + +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a +measure of phytoplankton biomass, were on average more than twice as high in the south basin, +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx + +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface + +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water + +Human Presence Remote Sensing January 22 - July 26, 2023JPEGOne of the wettest wet seasons +in northern Australia transformed large areas of the country’s desert landscape over the course +of many months in 2023. A string of major rainfall events that dropped 690 millimeters (27 +inches) between October 2022 and April 2023 made it the sixth-wettest season on record since +1900–1901.This series of false-color images illustrates the rainfall’s months-long effects + +downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and +bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer +(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), +water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following +weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached + +further downstream after another intense period of precipitation in March. This scene shows +that water had filled in some of the north-northwest trending ridges that are part of a vast +fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. +Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River +and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly + +the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed +about every three years; when it reaches especially high levels, it may take 18 months to +2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding +floodplains support hundreds of thousands of waterbirds and are designated as an Important +Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, + +the events of the 2022-2023 rainy season stood out in several ways. They occurred while La +Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern +Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) +In addition, major rains occurring in succession, as was the case with the January and March +events, have the overall effect of prolonging floods. That’s because vegetation that grows + +after the first event slows down the pulse of water that comes through in the next rain event.The +high water has affected both local communities and ecosystems. Floods have inundated cattle +farms and isolated towns on temporary islands. At the same time, they are a natural feature +of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support +biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS + +LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated +heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day +for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves +off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto +unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under + +water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February +5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast +of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September +18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone +in the Mediterranean inundated cities along the northeastern coast of Libya in early September + +2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, +was one of the worst hit by the storm and suffered extensive flooding and damage. On September +10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end +of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods +triggered two dams along the wadi to collapse. The failure of the second dam, located just + +one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the +city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods +out to sea. The images above show the city before and after the storm. The image on the right, +acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded +banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears + +muddier than in the image on the left, which shows the same area on August 25 and was acquired +by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, + +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological + +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s + +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods + +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected + +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua + +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher + +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown + +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color + +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating + +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough + +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there + +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory + +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image + +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke + +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, + +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, + +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. + +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena + +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands + +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour + +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts + +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the + +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone + +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts + +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported + +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, + +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and + +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters + +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. + +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, + +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how + +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from + +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land + +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for + +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and + +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer +and early fall of 2023. In September, low water levels limited barge shipments downriver and + +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This +is the second year in a row drought has caused the river to fall to near-record lows at many + +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they +are measured with respect to a chosen reference point. That is why some gauge height measurements + +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. + +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, + +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of + +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported + +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines +Parish are under drinking water advisories and have relied on bottled water for cooking and + +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States + +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily + +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low +water levels are making it difficult to ship goods down the river and allowing a wedge of + +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long +lake has a watershed that spans one million square kilometers (386,000 square miles), draining + +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of + +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that + +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels + +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous +to the lake were increased agricultural activities in the watershed and a higher frequency + +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a +measure of phytoplankton biomass, were on average more than twice as high in the south basin, + +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are + +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount + +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water +Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October +3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall +within the dry season in the western and northern Amazon rainforest, but a particularly acute + +lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI +(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched +Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. +On that date, the level of the river, the largest tributary of the Amazon River, had dropped +to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, + +the image on the left shows the same area on October 8, 2022, when the water level was 19.59 +meters, a more typical level for October. Rio Negro water levels continued to drop in the +days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some +areas in the Amazon River’s watershed have received less rain between July and September than +any year since 1980, Reuters reported. The drought has been particularly severe in the Rio + +Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern +Colombia.“Overall, this is a pretty unusual and extreme situation,” said RenĂ© Garreaud, an +atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought +appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific +functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation + +patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions +over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro +and other nearby rivers have disrupted drinking water supplies in hundreds of communities, +slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and +largest city of the Brazilian state of Amazonas, is the primary transportation hub for the + +upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other +industries with a presence in the city of two million people include chemical, ship, and electrical +equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data +from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water +level of the largest tributary of the Amazon River has hit a record low.Image of the Day for + +October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact +of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in +the basin is dramatically evident in this pair of images, which show that every body of water +has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water +in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent + +demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these +false-color images compare conditions along the Souris River, which reached a historic crest +at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, +these false-color images show the Mississippi River near Natchez, Mississippi. The image from +May 2011 shows flooded conditions. Land Floods January 22 - July 26, 2023JPEGOne of the wettest + +wet seasons in northern Australia transformed large areas of the country’s desert landscape +over the course of many months in 2023. A string of major rainfall events that dropped 690 +millimeters (27 inches) between October 2022 and April 2023 made it the sixth-wettest season +on record since 1900–1901.This series of false-color images illustrates the rainfall’s months-long +effects downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is + +green, and bare land is brown. The images were acquired by the Moderate Resolution Imaging +Spectroradiometer (MODIS) on NASA’s Terra satellite between January and July 2023.In the January +22 image (left), water was coursing through seasonally dry channels of the Georgina River +and Eyre Creek following weeks of heavy rains in northern Queensland. By April 21 (middle), +floodwaters had reached further downstream after another intense period of precipitation in + +March. This scene shows that water had filled in some of the north-northwest trending ridges +that are part of a vast fossil landscape of wind-formed dunes, while vegetation had emerged +in wet soil upstream. Then by July 26 (right), the riverbed had filled with even more vegetation.The +Georgina River and Eyre Creek drain approximately 210,000 square kilometers (81,000 square +miles), nearly the area of the United Kingdom. Visible in the lower part of the images, the + +lake gets refreshed about every three years; when it reaches especially high levels, it may +take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. These +three lakes and surrounding floodplains support hundreds of thousands of waterbirds and are +designated as an Important Bird Area.Seasonal flooding is a regular occurrence in these desert +river systems. However, the events of the 2022-2023 rainy season stood out in several ways. + +They occurred while La Niña conditions were in place over the tropical Pacific Ocean. (The +wettest seasons in northern Australia have all occurred during La Niña years, according to +Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, as was +the case with the January and March events, have the overall effect of prolonging floods. +That’s because vegetation that grows after the first event slows down the pulse of water that + +comes through in the next rain event.The high water has affected both local communities and +ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At +the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, +providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by +Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey + +Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new +growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water +View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing +amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of +heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water + +Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the +impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August +25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated +cities along the northeastern coast of Libya in early September 2023, causing thousands of + +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams +along the wadi to collapse. The failure of the second dam, located just one kilometer inland + +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier + +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, + +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological + +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s + +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods + +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected + +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua + +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher + +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown + +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color + +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating + +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough + +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there + +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory + +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image + +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke + +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, + +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, + +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. + +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena + +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands + +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour + +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts + +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the + +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone + +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts + +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported + +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, + +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and + +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters + +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. + +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, + +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how + +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from + +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land + +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for + +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and + +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer +and early fall of 2023. In September, low water levels limited barge shipments downriver and + +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This +is the second year in a row drought has caused the river to fall to near-record lows at many + +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they +are measured with respect to a chosen reference point. That is why some gauge height measurements + +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. + +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, + +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of + +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported + +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines +Parish are under drinking water advisories and have relied on bottled water for cooking and + +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States + +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily + +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low +water levels are making it difficult to ship goods down the river and allowing a wedge of + +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long +lake has a watershed that spans one million square kilometers (386,000 square miles), draining + +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of + +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that + +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels + +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous +to the lake were increased agricultural activities in the watershed and a higher frequency + +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a +measure of phytoplankton biomass, were on average more than twice as high in the south basin, + +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are + +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount + +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water +Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October +3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall +within the dry season in the western and northern Amazon rainforest, but a particularly acute + +lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI +(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched +Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. +On that date, the level of the river, the largest tributary of the Amazon River, had dropped +to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, + +the image on the left shows the same area on October 8, 2022, when the water level was 19.59 +meters, a more typical level for October. Rio Negro water levels continued to drop in the +days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some +areas in the Amazon River’s watershed have received less rain between July and September than +any year since 1980, Reuters reported. The drought has been particularly severe in the Rio + +Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern +Colombia.“Overall, this is a pretty unusual and extreme situation,” said RenĂ© Garreaud, an +atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought +appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific +functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation + +patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions +over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro +and other nearby rivers have disrupted drinking water supplies in hundreds of communities, +slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and +largest city of the Brazilian state of Amazonas, is the primary transportation hub for the + +upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other +industries with a presence in the city of two million people include chemical, ship, and electrical +equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data +from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water +level of the largest tributary of the Amazon River has hit a record low.Image of the Day for + +October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact +of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in +the basin is dramatically evident in this pair of images, which show that every body of water +has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water +in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent + +demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these +false-color images compare conditions along the Souris River, which reached a historic crest +at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, +these false-color images show the Mississippi River near Natchez, Mississippi. The image from +May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember + +6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter +rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried +out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline +lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a +vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat + +9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image +from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when +water filled most of the basin and salt deposits were only visible around the perimeter of +the lake. The replenishment followed a period of above-average precipitation that sent a surge +of freshwater into the basin, expanding its watery footprint. Drier conditions have since + +brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, +Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped +more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, +agricultural water use, and dam construction on rivers feeding the lake have contributed to +the decline. A shrinking Lake Urmia has implications for ecological and human health. The + +lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as +a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds +for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover +for migratory species. However, with low lake levels, what water remains becomes more saline +and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking + +lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds +and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with +respiratory health impacts among the local population.The relative effects of climate, water +usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery +during a 10-year restoration program beginning in 2013. However, the efficacy of that effort + +has been difficult to parse since strong rains also fell during that period. Some research +has concluded that climatic factors were primarily responsible for the recovery. NASA Earth +Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. +Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of +water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, + +2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest +since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and +fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day +Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the +1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic + +inhabitants can turn the water dark red. Image of the Day Water Water Color January 22 - July +26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of +the country’s desert landscape over the course of many months in 2023. A string of major rainfall +events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it +the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates + +the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades +of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and +July 2023.In the January 22 image (left), water was coursing through seasonally dry channels +of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. + +By April 21 (middle), floodwaters had reached further downstream after another intense period +of precipitation in March. This scene shows that water had filled in some of the north-northwest +trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation +had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even +more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers + +(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of +the images, the lake gets refreshed about every three years; when it reaches especially high +levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. +These three lakes and surrounding floodplains support hundreds of thousands of waterbirds +and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in + +these desert river systems. However, the events of the 2022-2023 rainy season stood out in +several ways. They occurred while La Niña conditions were in place over the tropical Pacific +Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, +according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, +as was the case with the January and March events, have the overall effect of prolonging floods. + +That’s because vegetation that grows after the first event slows down the pulse of water that +comes through in the next rain event.The high water has affected both local communities and +ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At +the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, +providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by + +Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey +Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new +growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water +View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing +amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of + +heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water +Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the +impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August +25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember +18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated + +cities along the northeastern coast of Libya in early September 2023, causing thousands of +deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst +hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over +100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow +valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams + +along the wadi to collapse. The failure of the second dam, located just one kilometer inland +of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to +news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. +The images above show the city before and after the storm. The image on the right, acquired +by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks + +of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier +than in the image on the left, which shows the same area on August 25 and was acquired by +Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the + +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. + +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers + +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours + +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational + +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color + +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in + +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. + +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered + +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability + +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from + +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean + +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the + +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level + +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage + +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires + +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced + +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton + +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. + +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution + +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran + +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa + +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts + +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported + +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach + +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during + +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast + +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust + +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling + +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other + +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use + +in the nearby community of Paine, increasing water use by farmers and in homes and pools, +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the + +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much + +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly + +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over + +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over + +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer + +and early fall of 2023. In September, low water levels limited barge shipments downriver and +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This + +is the second year in a row drought has caused the river to fall to near-record lows at many +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they + +are measured with respect to a chosen reference point. That is why some gauge height measurements +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in + +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts + +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in + +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river + +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines + +Parish are under drinking water advisories and have relied on bottled water for cooking and +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren + +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect + +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low + +water levels are making it difficult to ship goods down the river and allowing a wedge of +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long + +lake has a watershed that spans one million square kilometers (386,000 square miles), draining +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated + +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm + +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer + +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous + +to the lake were increased agricultural activities in the watershed and a higher frequency +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a + +measure of phytoplankton biomass, were on average more than twice as high in the south basin, +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View + +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the + +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water +Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October +3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall + +within the dry season in the western and northern Amazon rainforest, but a particularly acute +lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI +(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched +Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. +On that date, the level of the river, the largest tributary of the Amazon River, had dropped + +to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, +the image on the left shows the same area on October 8, 2022, when the water level was 19.59 +meters, a more typical level for October. Rio Negro water levels continued to drop in the +days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some +areas in the Amazon River’s watershed have received less rain between July and September than + +any year since 1980, Reuters reported. The drought has been particularly severe in the Rio +Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern +Colombia.“Overall, this is a pretty unusual and extreme situation,” said RenĂ© Garreaud, an +atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought +appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific + +functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation +patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions +over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro +and other nearby rivers have disrupted drinking water supplies in hundreds of communities, +slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and + +largest city of the Brazilian state of Amazonas, is the primary transportation hub for the +upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other +industries with a presence in the city of two million people include chemical, ship, and electrical +equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data +from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water + +level of the largest tributary of the Amazon River has hit a record low.Image of the Day for +October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact +of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in +the basin is dramatically evident in this pair of images, which show that every body of water +has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water + +in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent +demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these +false-color images compare conditions along the Souris River, which reached a historic crest +at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, +these false-color images show the Mississippi River near Natchez, Mississippi. The image from + +May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember +6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter +rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried +out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline +lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a + +vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat +9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image +from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when +water filled most of the basin and salt deposits were only visible around the perimeter of +the lake. The replenishment followed a period of above-average precipitation that sent a surge + +of freshwater into the basin, expanding its watery footprint. Drier conditions have since +brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, +Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped +more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, +agricultural water use, and dam construction on rivers feeding the lake have contributed to + +the decline. A shrinking Lake Urmia has implications for ecological and human health. The +lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as +a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds +for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover +for migratory species. However, with low lake levels, what water remains becomes more saline + +and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking +lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds +and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with +respiratory health impacts among the local population.The relative effects of climate, water +usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery + +during a 10-year restoration program beginning in 2013. However, the efficacy of that effort +has been difficult to parse since strong rains also fell during that period. Some research +has concluded that climatic factors were primarily responsible for the recovery. NASA Earth +Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. +Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of + +water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, +2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest +since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and +fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day +Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the + +1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic +inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September +30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high +levels, fueled by decades of human-caused climate warming and a recent boost from the natural +climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw + +particularly high temperatures, with implications for the health of coral reefs.Corals thrive +within a small range of temperatures and become stressed when water is too hot or cold. Bleaching +occurs when stressed corals expel the algae that live inside them, stripping corals of their +color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. +Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 + +caused widespread bleaching.Stress on corals can also be detected using data from satellites. +This animation shows the evolution of accumulated heat stress from July through September +2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate +of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s +Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA + +Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations +have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching +can result. At values of 8, coral bleaching and widespread mortality are likely. By midway +through this animation, in August, heat stress across much of the region already soared well +above both of those thresholds. According to NOAA, cumulative heat stress by late September + +2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching +was already observed in some areas as early as July. Notice that areas of coral reef (gray) +near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative +heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only +temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. + +Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level +2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA +Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from +Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn +Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large + +accumulations of heat stress beginning in summer 2023, with implications for the health of +coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes +View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, +with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of +the Day Life Water Image of the Day Heat Life Water Studying corals from above could help + +scientists understand how these critical ecosystems will weather a changing climate. Image +of the Day Land Life Water January 22 - July 26, 2023JPEGOne of the wettest wet seasons in +northern Australia transformed large areas of the country’s desert landscape over the course +of many months in 2023. A string of major rainfall events that dropped 690 millimeters (27 +inches) between October 2022 and April 2023 made it the sixth-wettest season on record since + +1900–1901.This series of false-color images illustrates the rainfall’s months-long effects +downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and +bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer +(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), +water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following + +weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached +further downstream after another intense period of precipitation in March. This scene shows +that water had filled in some of the north-northwest trending ridges that are part of a vast +fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. +Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River + +and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly +the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed +about every three years; when it reaches especially high levels, it may take 18 months to +2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding +floodplains support hundreds of thousands of waterbirds and are designated as an Important + +Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, +the events of the 2022-2023 rainy season stood out in several ways. They occurred while La +Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern +Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) +In addition, major rains occurring in succession, as was the case with the January and March + +events, have the overall effect of prolonging floods. That’s because vegetation that grows +after the first event slows down the pulse of water that comes through in the next rain event.The +high water has affected both local communities and ecosystems. Floods have inundated cattle +farms and isolated towns on temporary islands. At the same time, they are a natural feature +of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support + +biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS +LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated +heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day +for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves +off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto + +unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under +water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February +5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast +of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September +18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone + +in the Mediterranean inundated cities along the northeastern coast of Libya in early September +2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, +was one of the worst hit by the storm and suffered extensive flooding and damage. On September +10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end +of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods + +triggered two dams along the wadi to collapse. The failure of the second dam, located just +one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the +city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods +out to sea. The images above show the city before and after the storm. The image on the right, +acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded + +banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears +muddier than in the image on the left, which shows the same area on August 25 and was acquired +by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the + +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. + +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers + +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours + +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational + +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color + +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in + +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. + +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered + +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability + +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from + +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean + +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the + +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level + +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage + +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires + +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced + +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton + +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. + +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution + +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran + +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa + +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts + +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported + +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach + +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during + +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast + +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust + +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling + +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other + +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use + +in the nearby community of Paine, increasing water use by farmers and in homes and pools, +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the + +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much + +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly + +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over + +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over + +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer + +and early fall of 2023. In September, low water levels limited barge shipments downriver and +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This + +is the second year in a row drought has caused the river to fall to near-record lows at many +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they + +are measured with respect to a chosen reference point. That is why some gauge height measurements +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in + +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts + +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in + +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river + +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines + +Parish are under drinking water advisories and have relied on bottled water for cooking and +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren + +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect + +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low + +water levels are making it difficult to ship goods down the river and allowing a wedge of +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long + +lake has a watershed that spans one million square kilometers (386,000 square miles), draining +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated + +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm + +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer + +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous + +to the lake were increased agricultural activities in the watershed and a higher frequency +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a + +measure of phytoplankton biomass, were on average more than twice as high in the south basin, +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View + +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the + +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water +Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October +3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall + +within the dry season in the western and northern Amazon rainforest, but a particularly acute +lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI +(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched +Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. +On that date, the level of the river, the largest tributary of the Amazon River, had dropped + +to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, +the image on the left shows the same area on October 8, 2022, when the water level was 19.59 +meters, a more typical level for October. Rio Negro water levels continued to drop in the +days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some +areas in the Amazon River’s watershed have received less rain between July and September than + +any year since 1980, Reuters reported. The drought has been particularly severe in the Rio +Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern +Colombia.“Overall, this is a pretty unusual and extreme situation,” said RenĂ© Garreaud, an +atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought +appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific + +functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation +patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions +over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro +and other nearby rivers have disrupted drinking water supplies in hundreds of communities, +slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and + +largest city of the Brazilian state of Amazonas, is the primary transportation hub for the +upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other +industries with a presence in the city of two million people include chemical, ship, and electrical +equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data +from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water + +level of the largest tributary of the Amazon River has hit a record low.Image of the Day for +October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact +of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in +the basin is dramatically evident in this pair of images, which show that every body of water +has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water + +in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent +demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these +false-color images compare conditions along the Souris River, which reached a historic crest +at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, +these false-color images show the Mississippi River near Natchez, Mississippi. The image from + +May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember +6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter +rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried +out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline +lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a + +vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat +9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image +from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when +water filled most of the basin and salt deposits were only visible around the perimeter of +the lake. The replenishment followed a period of above-average precipitation that sent a surge + +of freshwater into the basin, expanding its watery footprint. Drier conditions have since +brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, +Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped +more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, +agricultural water use, and dam construction on rivers feeding the lake have contributed to + +the decline. A shrinking Lake Urmia has implications for ecological and human health. The +lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as +a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds +for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover +for migratory species. However, with low lake levels, what water remains becomes more saline + +and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking +lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds +and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with +respiratory health impacts among the local population.The relative effects of climate, water +usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery + +during a 10-year restoration program beginning in 2013. However, the efficacy of that effort +has been difficult to parse since strong rains also fell during that period. Some research +has concluded that climatic factors were primarily responsible for the recovery. NASA Earth +Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. +Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of + +water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, +2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest +since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and +fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day +Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the + +1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic +inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September +30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high +levels, fueled by decades of human-caused climate warming and a recent boost from the natural +climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw + +particularly high temperatures, with implications for the health of coral reefs.Corals thrive +within a small range of temperatures and become stressed when water is too hot or cold. Bleaching +occurs when stressed corals expel the algae that live inside them, stripping corals of their +color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. +Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 + +caused widespread bleaching.Stress on corals can also be detected using data from satellites. +This animation shows the evolution of accumulated heat stress from July through September +2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate +of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s +Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA + +Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations +have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching +can result. At values of 8, coral bleaching and widespread mortality are likely. By midway +through this animation, in August, heat stress across much of the region already soared well +above both of those thresholds. According to NOAA, cumulative heat stress by late September + +2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching +was already observed in some areas as early as July. Notice that areas of coral reef (gray) +near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative +heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only +temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. + +Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level +2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA +Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from +Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn +Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large + +accumulations of heat stress beginning in summer 2023, with implications for the health of +coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes +View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, +with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of +the Day Life Water Image of the Day Heat Life Water Studying corals from above could help + +scientists understand how these critical ecosystems will weather a changing climate. Image +of the Day Land Life Water Thank you for visiting nature.com. You are using a browser version +with limited support for CSS. To obtain the best experience, we recommend you use a more up +to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to +ensure continued support, we are displaying the site without styles and JavaScript.Advertisement + +Scientific Data volume 7, Article number: 112 (2020) Cite this article 30k Accesses126 Citations88 +AltmetricMetrics detailsRemotely sensed biomass carbon density maps are widely used for myriad +scientific and policy applications, but all remain limited in scope. They often only represent +a single vegetation type and rarely account for carbon stocks in belowground biomass. To date, +no global product integrates these disparate estimates into an all-encompassing map at a scale + +appropriate for many modelling or decision-making applications. We developed an approach for +harmonizing vegetation-specific maps of both above and belowground biomass into a single, +comprehensive representation of each. We overlaid input maps and allocated their estimates +in proportion to the relative spatial extent of each vegetation type using ancillary maps +of percent tree cover and landcover, and a rule-based decision schema. The resulting maps + +consistently and seamlessly report biomass carbon density estimates across a wide range of +vegetation types in 2010 with quantified uncertainty. They do so for the globe at an unprecedented +300-meter spatial resolution and can be used to more holistically account for diverse vegetation +carbon stocks in global analyses and greenhouse gas inventories.Measurement(s)biomass carbon +densityTechnology Type(s)digital curationFactor Type(s)climatic zone ‱ above or below ground + +‱ land coverSample Characteristic - Environmentorganic materialSample Characteristic - LocationEarth +(planet)Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.11872383Terrestrial +ecosystems store vast quantities of carbon (C) in aboveground and belowground biomass1. At +any point in time, these stocks represent a dynamic balance between the C gains of growth +and C losses from death, decay and combustion. Maps of biomass are routinely used for benchmarking + +biophysical models2,3,4, estimating C cycle effects of disturbance5,6,7, and assessing biogeographical +patterns and ecosystem services8,9,10,11. They are also critical for assessing climate change +drivers, impacts, and solutions, and factor prominently in policies like Reducing Emissions +from Deforestation and Forest Degradation (REDD+) and C offset schemes12,13,14. Numerous methods +have been used to map biomass C stocks but their derivatives often remain limited in either + +scope or extent12,15. There thus remains a critical need for a globally harmonized, integrative +map that comprehensively reports biomass C across a wide range of vegetation types.Most existing +maps of aboveground biomass (AGB) and the carbon it contains (AGBC) are produced from statistical +or data-driven methods relating field-measured or field-estimated biomass densities and spaceborne +optical and/or radar imagery12,15,16. They largely focus on the AGB of trees, particularly + +those in tropical landscapes where forests store the majority of the region’s biotic C in +aboveground plant matter. Land cover maps are often used to isolate forests from other landcover +types where the predictive model may not be appropriate such that forest AGB maps intentionally +omit AGB stocks in non-forest vegetation like shrublands, grasslands, and croplands, as well +as the AGB of trees located within the mapped extent of these excluded landcovers17. Non-forest + +AGB has also been mapped to some extent using similar approaches but these maps are also routinely +masked to the geographic extent of their focal landcover18,19,20,21. To date, there has been +no rigorous attempt to harmonize and integrate these landcover-specific, remotely sensed products +into a single comprehensive and temporally consistent map of C in all living biomass.Maps +of belowground biomass (BGB) and carbon density (BGBC) are far less common than those of AGB + +because BGB cannot be readily observed from space or airborne sensors. Consequently, BGB is +often inferred from taxa-, region-, and/or climate-specific “root-to-shoot” ratios that relate +the quantity of BGB to that of AGB22,23,24. These ratios can be used to map BGB by spatially +applying them to AGB estimates using maps of their respective strata5. In recent years, more +sophisticated regression-based methods have been developed to predict root-to-shoot ratios + +of some landcover types based on covariance with other biophysical and/or ecological factors25,26. +When applied spatially, these methods can allow for more continuous estimates of local BGB5,27. +Like AGBC, though, few attempts have been made to comprehensively map BGBC for the globe.Despite +the myriad of emerging mapping methods and products, to date, the Intergovernmental Panel +on Climate Change (IPCC) Tier-1 maps by Ruesch and Gibbs28 remains the primary source of global + +AGBC and BGBC estimates that transcend individual landcover types. These maps, which represents +the year 2000, were produced prior to the relatively recent explosion of satellite-based AGB +maps and they therefore rely on an alternative mapping technique called “stratify and multiply”15, +which assigns landcover-specific biomass estimates or “defaults” (often derived from field +measurements or literature reviews) to the corresponding classified grid cells of a chosen + +landcover map12. While this approach yields a comprehensive wall-to-wall product, it can fail +to capture finer-scale spatial patterns often evident in the field and in many satellite-based +products12,15. The accuracy of these maps is also tightly coupled to the quality and availability +of field measurements29 and the thematic accuracy and discontinuity of the chosen landcover +map.Given the wealth of landcover-specific satellite based AGB maps, a new harmonization method + +akin to “stratify and multiply” is needed to merge the validated spatial detail of landcover-specific +remotely sensed biomass maps into a single, globally harmonized product. We developed such +an approach by which we (i) overlay distinct satellite-based biomass maps and (ii) proportionately +allocate their estimates to each grid cell (“overlay and allocate”). Specifically, we overlay +continental-to-global scale remotely sensed maps of landcover-specific biomass C density and + +then allocate fractional contributions of each to a given grid cell using additional maps +of percent tree cover, thematic landcover and a rule-based decision tree. We implement the +new approach here using temporally consistent maps of AGBC as well as matching derived maps +of BGBC to generate separate harmonized maps of AGBC and BGBC densities. In addition, we generate +associated uncertainty layers by propagating the prediction error of each input dataset. The + +resulting global maps consistently represent biomass C and associated uncertainty across a +broad range of vegetation in the year 2010 at an unprecedented 300 meter (m) spatial resolution.Our +harmonization approach (Fig. 1) relies on independent, landcover-specific biomass maps and +ancillary layers, which we compiled from the published literature (Table 1). When published +maps did not represent our epoch of interest (i.e. grasslands and croplands) or did not completely + +cover the necessary spatial extent (i.e. tundra vegetation), we used the predictive model +reported with the respective map to generate an updated version that met our spatial and temporal +requirements. We then used landcover specific root-to-shoot relationships to generate matching +BGBC maps for each of the input AGBC maps before implementing the harmonization procedure. +Below we describe, in detail, the methodologies used for mapping AGBC and BGBC of each landcover + +type and the procedure used to integrate them.Generalized, three-step workflow used to create +harmonized global biomass maps. In step one, woody AGB maps are prepared, combined, converted +to AGBC density and used to create separate but complementary maps of BGBC. In step two, a +similar workflow is used to generate matching maps of AGBC and BGBC for tundra vegetation, +grasses, and annual crops. In step three, all maps are combined using a rule-based decision + +tree detailed in Fig. 3 to generate comprehensive, harmonized global maps. All input data +sources are listed and described in Table 1.Since the first remotely sensed woody AGB maps +were published in the early 1990s, the number of available products has grown at an extraordinary +pace16 and it can thus be challenging to determine which product is best suited for a given +application. For our purposes, we relied on the GlobBiomass AGB density map30 as our primary + +source of woody AGB estimates due to its precision, timestamp, spatial resolution, and error +quantification. It was produced using a combination of spaceborne optical and synthetic aperture +radar (SAR) imagery and represents the year 2010 at a 100 m spatial resolution – making it +the most contemporary global woody AGB currently available and the only such map available +for that year. Moreover, GlobBiomass aims to minimize prediction uncertainty to less than + +30% and a recent study suggests that it has high fidelity for fine-scale applications31.The +GlobBiomass product was produced by first mapping the growing stock volume (GSV; i.e. stem +volume) of living trees, defined following Food and Agriculture Organization (FAO) guidelines32 +as those having a diameter at breast height (DBH) greater than 10 centimeters (cm). AGB density +was then determined from GSV by applying spatialized biomass expansion factors (BEFs) and + +wood density estimates. These factors were mapped using machine learning methods trained from +a suite of plant morphological databases that compile thousands of field measurements from +around the globe33. The resulting AGB estimates represent biomass in the living structures +(stems, branches, bark, twigs) of trees with a DBH greater than 10 cm. This definition may +thereby overlook AGB of smaller trees and/or shrubs common to many global regions. Unlike + +other maps, though, the GlobBiomass product employs a subpixel masking procedure that retains +AGB estimates in 100 m grid cells in which any amount of tree cover was detected in finer +resolution (30 m) imagery34. This unique procedure retains AGB estimates in tree-sparse regions +like savannahs, grasslands, croplands, and agroforestry systems where AGB is often overlooked17, +as well as in forest plantations. The GlobBiomass product is the only global map that also + +includes a dedicated uncertainty layer reporting the standard error of prediction. We used +this layer to propagate uncertainty when converting AGB to AGBC density, modelling BGBC, and +integrating with C density estimates of other vegetation types.Bouvet et al.35 – some of whom +were also participants of the GlobBiomass project – independently produced a separate AGB +density map for African savannahs, shrublands and dry woodlands circa 2010 at 25 m spatial + +resolution35 (hereafter “Bouvet map”), which we included in our harmonized product to begin +to address the GlobBiomass map’s potential omission of small trees and shrubs that do not +meet the FAO definition of woody AGB. This continental map of Africa is based on a predictive +model that directly relates spaceborne L-band SAR imagery – an indirect measure of vegetation +structure that is sensitive to low biomass densities36 – with region-specific, field-measured + +AGB. Field measurements (n = 144 sites) were compiled from 7 different sampling campaigns +– each specifically seeking training data for biomass remote sensing – that encompassed 8 +different countries35. The resulting map is not constrained by the FAO tree definition and +is masked to exclude grid cells in which predicted AGB exceeds 85 megagrams dry mater per +hectare (Mg ha−1) – the threshold at which the SAR-biomass relationship saturates. To avoid + +extraneous prediction, it further excludes areas identified as “broadleaved evergreen closed-to-open +forest”, “flooded forests”, “urban areas” and “water bodies” by the European Space Agency’s +Climate Change Initiative (CCI) Landcover 2010 map37 and as “bare areas” in the Global Land +Cover (GLC) 2000 map38. While the Bouvet map is not natively accompanied by an uncertainty +layer, its authors provided us with an analytic expression of its uncertainty (SE; standard + +error of prediction) as a function of estimated AGB (Eq. 1) which we used to generate an uncertainty +layer for subsequent error propagation.We combined the GlobBiomass and Bouvet products to +generate a single woody biomass map by first upscaling each map separately to a matching 300 +m spatial resolution using an area-weighted average to aggregate grid cells, and then assigning +the Bouvet estimate to all overlapping grid cells, except those identified by the CCI Landcover + +2010 map as closed or flooded forest types (Online-only Table 1) which were not within the +dryland domain of the Bouvet map. While more complex harmonization procedures based on various +averaging techniques have been used by others39,40, their fidelity remains unclear since they +fail to explicitly identify and reconcile the underlying source of the inputs’ discrepancies41. +We thus opted to use a more transparent ruled-based approach when combining these two woody + +biomass maps, which allows users to easily identify the source of a grid cell’s woody biomass +estimate. Given the local specificity of the training data used to produce the Bouvet map, +we chose to prioritize its predictions over those of the GlobBiomass product when within its +domain. In areas of overlap, the Bouvet map values tend to be lower in moist regions and higher +in dryer regions (Fig. 2), though, where used, these differences rarely exceed ±25 megagrams + +C per hectare (MgC ha−1).Difference between underlying woody aboveground biomass maps in Africa. +Maps considered are the GlobBiomass30 global map and the Bouvet35 map of Africa. Both maps +were aggregated to a 300 m spatial resolution and converted to C density prior to comparison +using the same schema. The difference map was subsequently aggregated to a 3 km spatial resolution +and reprojected for visualization. Negative values denote lower estimates by Bouvet et al.35, + +while positive values denote higher estimates.We then converted all woody AGB estimates to +AGBC by mapping climate and phylogeny-specific biomass C concentrations from Martin et al.42. +Climate zones were delineated by aggregating classes of the Köppen-Gieger classification43 +(Table 2) to match those of Martin et al.42. Phylogenetic classes (angiosperm, gymnosperm +and mixed/ambiguous) were subsequently delineated within each of these zones using aggregated + +classes of the CCI Landcover 2010 map (Online-only Table 1). Martin et al.42 only report values +for angiosperms and gymnosperms so grid cells with a mixed or ambiguous phylogeny were assigned +the average of the angiosperm and gymnosperm values and the standard error of this value was +calculated from their pooled variance. Due to residual classification error in the aggregated +phylogenetic classes, we weighted the phylogeny-specific C concentration within each climate + +zone by the binary probability of correctly mapping that phylogeny (i.e. user’s accuracy)44 +using Eq. 2where, within each climate zone, ÎŒc is the mean probability-weighted C concentration +of the most probable phylogeny, ÎŒm is the mean C concentration of that phylogeny from Martin +et al.42, pm is the user’s accuracy of that phylogeny’s classification (Table 3), and ÎŒn and +ÎŒo are the mean C concentrations of the remain phylogenetic classes from Martin et al.42. + +Standard error estimates for these C concentrations were similarly weighted using summation +in quadrature (Eq. 3)where \({\sigma }_{c}\) is the probability-weighted standard error of +the most probable phylogeny’s C concentration and \({\sigma }_{m}\), \({\sigma }_{n}\) and +\({\sigma }_{o}\) are the standard errors of the respective phylogeny-specific C concentrations +from Martin et al.42. Probability-weighted C concentrations used are reported in Table 4.Mapped, + +probability-weighted C estimates were then arithmetically applied to AGB estimates. Uncertainty +associated with this correction was propagated using summation in quadrature of the general +form (Eq. 4)where \({\mu }_{f}=f(i,j,\ldots ,k)\), \({\sigma }_{f}\) is the uncertainty of +ÎŒf, and \({\sigma }_{i},{\sigma }_{j},\ldots ,{\sigma }_{k}\), are the respective uncertainty +estimates of the dependent parameters (standard error unless otherwise noted). Here, ÎŒf, is + +the estimated AGBC of a given grid cell, and is the product of its woody AGB estimate, and +its corresponding C concentration.The tundra and portions of the boreal biome are characterized +by sparse trees and dwarf woody shrubs as well as herbaceous cover that are not included in +the GlobBiomass definition of biomass. AGB density of these classes has been collectively +mapped by Berner et al.18,45 for the North Slope of Alaska from annual Landsat imagery composites + +of the normalized difference vegetation index (NDVI) and a non-linear regression-based model +trained from field measurements of peak AGB that were collected from the published literature +(n = 28 sites). Berner et al.18 note that while these field measurements did not constitute +a random or systematic sample, they did encompass a broad range of tundra plant communities. +In the absence of a global map and due the sparsity of high quality Landsat imagery at high + +latitudes, we extended this model to the pan-Arctic and circumboreal regions using NDVI composites +created from daily 250 m MODIS Aqua and Terra surface reflectance images46,47 that were cloud +masked and numerically calibrated to Landsat ETM reflectance – upon which the tundra model +is based – using globally derived conversion coefficients48. We generated six separate 80th +percentile NDVI composites circa 2010 – one for each of the MODIS missions (Aqua and Terra) + +in 2009, 2010 and 2011 – following Berner et al.18. We chose to use three years of imagery +(circa 2010) rather than just one (2010) to account for the potential influence that cloud +masking may exert upon estimates of the 80th NDVI percentile in a single year. We then applied +the tundra AGB model to each composite, converted AGB estimates to AGBC by assuming a biomass +C fraction of 49.2% (SE = 0.8%)42 and generated error layers for each composite from the reported + +errors of the AGB regression coefficients and the biomass C conversion factor using summation +in quadrature as generally described above (Eq. 4). A single composite of tundra AGBC circa +2010 was then created as the pixelwise mean of all six composites. We also generated a complementary +uncertainty layer representing the cumulative standard error of prediction, calculated as +the pixelwise root mean of the squared error images in accordance with summation in quadrature. + +Both maps were upscaled from their native 250 m spatial resolution to a 300 m spatial resolution +using an area weighted aggregation procedure, whereby pixels of the 300 m biomass layer was +calculated as the area weighted average of contained 250 m grid cells, and the uncertainty +layer was calculated – using summation in quadrature – as the root area-weighted average of +the contained grid cells squared.Grassland AGBC density was modelled directly from maximum + +annual NDVI composites using a non-linear regression-based model developed by Xia et al.19 +for mapping at the global scale. This model was trained by relating maximum annual NDVI as +measured by the spaceborne Advanced Very High-Resolution Radiometer (AVHRR) sensor to globally +distributed field measurements of grassland AGBC that were compiled from the published literature +(81 sites for a total of 158 site-years). Like the tundra biomass training data, these samples + +did not constitute a random or systematic sample but do encompass a comprehensive range of +global grassland communities. Given the inevitable co-occurrence of trees in the AVHRR sensor’s +8 km resolution pixels upon which the model is trained, it’s predictions of grassland AGBC +are relatively insensitive to the effects of co-occurring tree cover. We thereby assume that +its predictions for grid cells containing partial tree cover represent the expected herbaceous + +AGBC density in the absence of those trees. Maximum model predicted AGBC (NDVI = 1) is 2.3 +MgC ha−1 which is comparable to the upper quartile of herbaceous AGBC estimates from global +grasslands49 and suggests that our assumption will not lead to an exaggerated estimation. +For partially wooded grid cells, we used modelled grassland AGBC density to represent that +associated with the herbaceous fraction of the grid cell in a manner similar to Zomer et al.17 + +as described below (See “Harmonizing Biomass Carbon Maps”).We applied the grassland AGBC model +to all grid cells of maximum annual NDVI composites produced from finer resolution 16-day +(250 m) MODIS NDVI imagery composites circa 201050,51. Here again, three years of imagery +were used to account for potential idiosyncrasies in a single year’s NDVI composites resulting +from annual data availability and quality. As with AGB of tundra vegetation, annual composites + +(2009–2011) were constructed separately from cloud-masked imagery collected by both MODIS +missions (Aqua and Terra; n = 6) and then numerically calibrated to AVHRR reflectance using +globally derived conversion coefficients specific to areas of herbaceous cover52. We then +applied the AGBC model to each of these composites and estimated error for each composite +from both the AVHRR calibration (standard deviation approximated from the 95% confidence interval + +of the calibration scalar) and the AGBC model (relative RMSE) using summation in quadrature. +A single map of grassland AGBC circa 2010 was then created as the pixelwise mean of all six +composites and an associated error layer was created as the pixelwise root mean of the squared +error images. Both maps were aggregated from their original 250 m resolution to 300 m to facilitate +harmonization using the area-weighted procedure described previously for woody and tundra + +vegetation (see section 1.2).Prior to harvest, cropland biomass can also represent a sizable +terrestrial C stock. In annually harvested cropping systems, the maximum standing biomass +of these crops can be inferred from annual net primary productivity (ANPP). While spaceborne +ANPP products exist, they generally perform poorly in croplands53,54. Instead, cropland ANPP +is more commonly derived from crop yields20,21,53. We used globally gridded, crop-specific + +yields of 70 annually harvested herbaceous commodity crops circa 2000 by Monfreda et al.20 +– the only year in which these data were available. These maps were produced by spatially +disaggregating crop-yield statistics for thousands of globally distributed administrative +units throughout the full extent of a satellite-based cropland map20. These maps were combined +with crop-specific parameters (Online-only Table 2) to globally map AGBC as aboveground ANPP + +for each crop following the method of Wolf et al.21. This method can be simplified as (Eq. +5)where y is the crop’s yield (Mg ha−1), ω is the dry matter fraction of its harvested biomass, +h is its harvest index (fraction of total AGB collected at harvest) and c is the carbon content +fraction of its harvested dry mass. This simplification assumes, following Wolf et al.21, +that 2.5% of all harvested biomass is lost between the field and farmgate and that unharvested + +residue and root mass is 44% C.Total cropland AGBC density was then calculated as the harvested-area-weighted +average of all crop-specific AGBC estimates within a given grid cell. Since multiple harvests +in a single year can confound inference of maximum AGBC from ANPP, we further determined the +harvest frequency (f) of each grid cell by dividing a cell’s total harvested area (sum of +the harvested area of each crop reported within a given grid cell) by its absolute cropland + +extent as reported in a complementary map by Ramankutty et al.55. If f was greater than one, +multiple harvests were assumed to have occurred and AGBC was divided by f to ensure that AGBC +estimates did not exceed the maximum standing biomass density.Since the yields of many crops +and, by association, their biomass have changed considerably since 200056,57, we calibrated +our circa 2000 AGBC estimates to the year 2010 using local rates of annual ANPP change (MgC + +ha−1 yr−1) derived as the Theil-Sen slope estimator – a non-parametric estimator that is relatively +insensitive to outliers – of the full MODIS Terra ANPP timeseries (2000–2015)58. Total ANPP +change between 2000 and 2010 for each grid cell was calculated as ten times this annual rate +of change. Since MODIS ANPP represents C gains in both AGB and BGB, we proportionately allocated +aboveground ANPP to AGBC using the total root-to-shoot ratio derived from the circa 2000 total + +crop AGBC and BGBC maps (described below). Since error estimates were not available for the +yield maps or the crop-specific parameters used to generate the circa 2000 AGBC map, estimated +error of the circa 2010 crop AGBC map was exclusively based on that of the 2000–2010 correction. +The error of this correction was calculated as the pixel-wise standard deviation of bootstrapped +simulations (n = 1000) in which a random subset of years was omitted from the slope estimator + +in each iteration. The 8 km resolution circa 2000 AGBC map and error layer were resampled +to 1 km to match the resolution of MODIS ANPP using the bilinear method prior to ANPP correction +and then further resampled to 300 m to facilitate harmonization.Woody crops like fruit, nut, +and palm oil plantations were not captured using the procedure just described and their biomass +was instead assumed to be captured by the previously described woody biomass products which + +retained biomass estimates in all pixels where any amount of tree cover was detected at the +sub-pixel level (see section 1.1).Matching maps of BGBC and associated uncertainty were subsequently +produced for each of the landcover-specific AGBC maps using published empirical relationships.With +the exception of savannah and shrubland areas, woody BGBC was modelled from AGBC using a multiple +regression model by Reich et al.25 that considers the phylogeny, mean annual temperature (MAT), + +and regenerative origin of each wooded grid cell and that was applied spatially using maps +of each covariate in a fashion similar to other studies5,27. Tree phylogeny (angiosperm or +gymnosperm) was determined from aggregated classes of the CCI Landcover 2010 map37 (Online-only +Table 1) with phylogenetically mixed or ambiguous classes assumed to be composed of 50% of +each. MAT was taken from version 2 of the WorldClim bioclimatic variables dataset (1970–2000) + +at 1 km resolution59 and resampled to 300 m using the bilinear method. Since there is not +a single global data product mapping forest management, we determined tree origin – whether +naturally propagated or planted – by combining multiple data sources. These data included +(i) a global map of “Intact Forest Landscapes” (IFL) in the year 201360 (a conservative proxy +of primary, naturally regenerating forests defined as large contiguous areas with minimal + +human impact), (ii) a Spatial Database of Planted Trees (SDPT) with partial global coverage61, +(iii) national statistics reported by the FAO Global Forest Resources Assessment (FRA) on +the extent of both naturally regenerating and planted forests and woodlands within each country +in the year 201062, and (iv) national statistics reported by the FAOSTAT database (http://www.fao.org/faostat) +on the planted area of plantation crops in 2010. Within each country, we assumed that the + +total area of natural and planted trees was equal to the corresponding FRA estimates. If the +FAOSTAT-reported area of tree crops exceeded FRA-reported planted area, the difference was +added to FRA planted total. All areas mapped as IFL were assumed to be of natural origin and +BGB was modelled as such. Likewise, besides the exceptions noted below, all tree plantations +mapped by the SDPT were assumed to be of planted origin. In countries where the extent of + +the IFL or SDPT maps fell short of the FRA/FAOSTAT reported areas of natural or planted forests, +respectively, we estimated BGBC in the remaining, unknown-origin forest grid cells of that +country (BGBCu), as the probability-weighted average of the planted and natural origin estimates +using Eq. 6where \(BGB{C}_{p}\) and \(BGB{C}_{n}\) are the respective BGBC estimates for a +grid cell assuming entirely planted and natural origin, respectively, and \({\Delta }_{p}\) + +and \({\Delta }_{n}\) are the respective differences between (i) the FRA/FAOSTAT and (ii) +mapped extent of planted and natural forest within the given grid cell’s country. While the +mapped extent of IFL forests within a given country never exceeded that country’s FRA reported +natural forest extent, there were infrequent cases (n = 22 of 257) in which the mapped extent +of tree plantations exceeded the corresponding FRA/FAOSTAT estimate of planted forest area. + +In these cases, we down-weighted the BGB estimates of SDPT forests in a similar fashion such +that the weight of their planted estimate (\({\omega }_{p}\)) was equal to the quotient of +(i) the FRA/FAOSTAT planted area and (ii) the SDPT extent within the country, and the weight +of the natural origin estimate applied to the SDPT extent (\({\omega }_{n}\)) was equal to +\(1-{\omega }_{p}\).A BGBC error layer was then produced using summation in quadrature from + +the standard error estimates of the model coefficients, the AGBC error layer, the relative +RMSE of MAT (27%), and the derived global uncertainty of the phylogeny layer. Phylogeny error +was calculated as the Bernoulli standard deviation (ÎŽ) of the binary probability (p) of correct +classification (i.e. “area weighted user’s accuracy”44; Table 3) using Eq. 7.Since savannahs +and shrublands are underrepresented in the regression-based model25, their BGBC was instead + +estimated using static root-to-shoot ratios reported by Mokany et al.22, which are somewhat +conservative in comparison to the IPCC Tier-1 defaults23,24 put favoured for consistency with +methods used for grasslands (see below). Error was subsequently mapped from that of the AGBC +estimates and the root-to-shoot ratios applied (Table 5).BGBC of tundra vegetation was mapped +from AGBC using a univariate regression model derived by Wang et al.26 that predicts root-to-shoot + +ratio as a function of MAT. We applied the model using the WorldClim version 2 MAT map59 and +propagated error from the AGBC estimates, the relative RMSE of MAT and the standard error +of regression coefficients. Where tundra AGB exceeded 25 Mg ha−1 – the maximum field-measured +shrub biomass reported by Berner et al.18 – vegetation was considered to include trees and +the Reich et al.25 method described earlier for woody vegetation was used instead.In the absence + +of a continuous predictor of grassland root-to-shoot ratios, we applied climate specific root-to-shoot +ratios from Mokany et al.22 to the corresponding climate regions of the Köppen-Gieger classification43 +(Table 2). Here, again, these ratios vary slightly from the IPCC Tier-1 defaults23,24 but +were chosen for their greater sample size and specificity. Grassland BGBC error was mapped +from the error of the AGBC estimates and the respective root-to-shoot ratios.Cropland BGBC + +was again estimated from crop-specific yields and morphological parameters (Online-only Table +2) following Wolf et al.21 and Eq. 8where y is the crop’s yield (Mg ha−1), r is the root-to-shoot +ratio of the crop, and h is its harvest index. Here again we assume that 2.5% of all harvested +biomass is lost between the field and farmgate and that root biomass is 44% C, following Wolf +et al.21. BGBC error was mapped from the error of the 2000-to-2010 ANPP correction for BGBC + +allocation as described above for cropland AGBC.The AGBC and BGBC maps were harmonized separately +following the same general schema (Fig. 3). Given that our harmonized woody biomass map contains +biomass estimates for grid cells in which any amount of tree cover was detected at the subpixel +level (see section 1.1), we conserved its estimates regardless of the landcover reported by +the 2010 CCI map in order to more fully account for woody biomass in non-forested areas17. + +We then used the MODIS continuous vegetation fields percent tree cover map for 201063 to allocate +additional biomass density associated with the most probable herbaceous cover (grass or crop) +to each grid cell in quantities complementary to that of the grid cell’s fractional tree cover +estimate (Eq. 9)where ÎŒT is the total biomass estimate of a grid cell, ÎŒw is the woody biomass +estimate for the grid cell, ÎŒh is its herbaceous biomass estimate, and q is the MODIS fractional + +tree cover of the grid cell. Since MODIS tree cover estimates saturate at around 80%64, we +linearly stretched values such that 80% was treated as complete tree cover (100%). Moreover, +we acknowledge that percent cover can realistically exceed 100% when understory cover is considered +but we were unable to reasonably determine the extent of underlying cover from satellite imagery. +As such, our approach may underestimate the contribution of herbaceous C stocks in densely + +forested grid cells. The most likely herbaceous cover type was determined from the CCI Landcover +2010 map, which we aggregated into two “likely herbaceous cover” classes – grass or crop – +based on the assumed likelihood of cropland in each CCI class (Online-only Table 1). However, +due to inherent classification error in the native CCI Landcover map, when determining the +herbaceous biomass contribution we weighted the relative allocation of crop and grass biomass + +to a given grid cell based on the probability of correct classification by the CCI map (i.e. +“user’s accuracy”, Table 6) of the most probable herbaceous class (\({p}_{i}\)) such that +ÎŒh can be further expressed as (Eq. 10)where ÎŒi is the predicted biomass of the most probable +herbaceous class, and ÎŒj is that of the less probable class.Decision tree used to allocate +landcover-specific biomass estimates to each grid cell of our harmonized global products.The + +uncertainty of a grid cell’s total AGBC or BGBC estimate (\({\sigma }_{T}\)) was determined +and mapped from that of its components (\({\mu }_{w}\,{\rm{and}}\,{\mu }_{h}\)) by summation +in quadrature which can be simplified as (Eq. 11)where \({\sigma }_{w}\) is the error of the +grid cell’s estimated ÎŒw, \({\sigma }_{h}\) is the error of its estimated ÎŒh, and \({\sigma +}_{q}\) is the error of its q. Here, \({\sigma }_{h}\) can be further decomposed and expressed + +as Eq. 12 to account for the accuracy weighted allocation procedure expressed previously (Eq. +10)where \({\sigma }_{i}\) is the error of the estimated biomass density of the most probable +herbaceous class, \({\delta }_{i}\) is the estimated standard deviation of that class’s Bernoulli +probability (p; Eq. 7), and \({\sigma }_{j}\) is the error of the estimated biomass density +of the less probable herbaceous subclass.Exceptions to the above schema were made in the tundra + +and boreal biomes – as delineated by the RESOLVE Ecoregions 2017 biome polygons65 – where +thematic overlap was likely between the woody and tundra plant biomass maps. A separate set +of decision rules (Fig. 3) was used to determine whether grid cells in these biomes were to +be exclusively allocated the estimate of the tundra plant map or that of the fractional allocation +procedure described above. In general, any land in these biomes identified as sparse landcover + +by the CCI landcover map (Online-only Table 1) was assigned the tundra vegetation estimate. +In addition, lands north of 60° latitude with less than 10% tree cover or where the tundra +AGBC estimate exceeded that of the woody AGBC estimate were also exclusively assigned the +tundra vegetation estimate. Lands north of 60° latitude not meeting these criteria were assigned +the woody value with the additional contribution of grass.Subtle numerical artefacts emerged + +from the divergent methodologies employed north and south of 60°N latitude. These were eliminated +by distance weighting grid cells within 1° of 60°N based on their linear proximity to 60°N +and then averaging estimates such that values at or north of 61°N were exclusively based on +the northern methodology, those at 60°N were the arithmetic average of the two methodologies +and those at or south of 59°N were exclusively based on the southern methodology. This produced + +a seamless, globally harmonized product that integrates the best remotely sensed estimates +of landcover-specific C density. Water bodies identified as class “210” of the CCI 2010 landcover +map were then masked from our final products.Data layers (n = 4, Table 7) for the maps of +AGBC and BGBC density (Fig. 4) as well as their associated uncertainty maps which represent +the combined standard error of prediction (Fig. 5) are available as individual 16-bit integer + +rasters in GeoTiff format. All layers are natively in a WGS84 Mercator projection with a spatial +resolution of approximately 300 m at the equator and match that of the ESA CCI Landcover Maps37. +Raster values are in units megagrams C per hectare (MgC ha−1) and have been scaled by a factor +of ten to reduce file size. These data are accessible through the Oak Ridge National Laboratory +(ORNL) DAAC data repository (https://doi.org/10.3334/ORNLDAAC/1763)66. In addition, updated + +and/or derived vegetation-specific layers that were used to create our harmonized 2010 maps +are available as supplemental data on figshare67.Globally harmonized maps of above and belowground +living biomass carbon densities. (a) Aboveground biomass carbon density (AGBC) and (b) belowground +biomass carbon density (BGBC) are shown separately. Maps have been aggregated to a 5 km spatial +resolution and reprojected here for visualization.Uncertainty of grid cell level above and + +belowground biomass carbon density estimates. Uncertainty is shown here as the coefficient +of variation (%; standard error layer divided by mean estimate layer) of estimated AGBC (a) +and BGBC (b) densities after harmonization. Maps have been aggregated to a 5 km spatial resolution +and projected for visualization.Our harmonized products rely almost exclusively upon maps +and models that have been rigorously validated by their original producers and were often + +accompanied by constrained uncertainty estimates. Throughout our harmonization procedure, +we strived to conserve the validity of each of these products by minimizing the introduction +of additional error and by tracking any introductions, as described above, such that the final +error layers represent the cumulative uncertainty of the inputs used. Ground truth AGB and +BGB data are almost always collected for individual landcover types. Consequently, we are + +unable to directly assess the validity of our integrated estimates beyond their relationships +to individual landcover-specific estimates and the extents to which they were modified from +their original, previously-validated form prior to and during our harmonization procedure.Temporal +and spatial updates made to existing landcover-specific maps of non-tree AGB resulted in relatively +small changes to their predictions. For example, we used numerically calibrated MODIS imagery + +to extend the Landsat-based tundra plant AGB model beyond its native extent (the North Slope +of Alaska) to the pan-Arctic region since neither a comparable model nor a consistent Landsat +time series were available for this extent. We assessed the effects of these assumptions by +comparing our predictions for the North Slope with those of the original map18 (Fig. 6a). +Both positive and negative discrepancies exist between ours and the original, though these + +rarely exceed ±2 MgC ha−1 and no discernibly systematic bias was evident.Differences between +landcover-specific AGBC estimates from the original published maps and the modified versions +used as inputs to create the 2010 harmonized global maps. Tundra vegetation AGBC (a) is compared +to the Landsat-based map of Berner et al.45 for the north slope of Alaska after converting +it to units MgC ha−1. Here, the comparison map was subsequently aggregated to a 1 km resolution + +and reprojected for visualization. Grassland AGBC (b) is compared to the AVHRR-based map of +Xia et al.19 which represents the average estimate between 1982–2006. For visualization, the +map was aggregated to a 5 km resolution and subsequently reprojected after being masked to +MODIS IGBP grasslands in the year 200685 following Xia et al.19. As such, this map does not +necessarily represent the spatial distribution of grid cells in which grassland estimates + +were used. Cropland AGBC (c) is compared to the original circa 2000 estimates to assess the +effects of the 2000-to-2010 correction. The map is masked to the native extent of the combined +yield maps and aggregated to a 5 km resolution for visualization. For all maps, negative values +indicate that our circa 2010 estimates are lower than those of the earlier maps while positive +values indicate higher estimates.Our updated map of grassland biomass carbon in the year 2010 + +was similarly made by applying the original AVHRR-based model to calibrated MODIS imagery. +This too resulted in only subtle changes to the original biomass map (Fig. 6b) that were rarely +in excess of 0.5 MgC ha−1. In most areas, our estimates were higher than those of Xia et al.19 +who mapped the mean AGBC density between 1986 and 2006. Most of these elevated estimates corresponded +with areas in which significant NDVI increases (“greening”) have been reported while notably + +lower estimates in the Argentine Monte and Patagonian steppe biomes of southern South America, +likewise, correspond with areas of reported “browning”68,69. Both greening and browning trends +are well documented phenomena and have been linked to climatic changes70. Moreover, we further +compared AGBC estimates from both the original Xia et al.19 map and our 2010 update to AGBC +field measurements coordinated by the Nutrient Network that were collected from 48 sites around + +the world between 2007 and 200949. The RMSE (0.68 MgC ha−1) of our updated map was 10% less +that of the Xia et al. map for sites with less than 40% tree cover. Likewise, our 2010 estimates +were virtually unbiased (bias = −0.01 MgC ha−1) in comparison to the Xia map (bias = 0.25 +MgC ha−1). While still noisy, these results suggest that our temporal update improved the +overall accuracy of estimated grassland AGBC.Finally, cropland biomass carbon maps were also + +updated from their native epoch (2000) to 2010 using pixel-wise rates of MODIS ANPP change +over a ten-year period. While MODIS ANPP may be a poor snapshot of crop biomass in a single +year, we assumed that its relative change over time reflects real physiological shifts affecting +the cropland C cycle. This correction also resulted in only small differences that rarely +exceeded ±2 MgC ha−1 and that, spatially, correspond well with observed declines in the yields + +of select crops that have been linked to climate change71,72 (Fig. 6c). Nonetheless, updated +global yield maps comparable to those available for 2000 would greatly improve our understanding +of the interactions between climate change, crop yields, and C dynamics.Belowground biomass +is notoriously difficult to measure, model, and also to validate. We accounted for the reported +uncertainty of nearly every variable considered when estimating belowground biomass and pixel-level + +uncertainty, but we were unable to perform an independent validation of our harmonized estimates +at the pixel level due to a paucity of globally consistent field data. To complete such a +task, a globally orchestrated effort to collect more BGB samples data across all vegetation +types is needed.Given this lack of data, we instead compared the estimated uncertainty of +our BGBC maps to that of our AGBC estimates to infer the sources of any divergence (Fig. 5). + +As expected, our cumulative BGBC uncertainty layer generally reveals greater overall uncertainty +than our AGBC estimates, with BGBC uncertainty roughly twice that of AGBC throughout most +of the globe. The highest absolute uncertainty was found in biomass rich forests. Arid woodlands, +especially those of the Sahel and eastern Namibia, generally had the greatest relative BGBC +uncertainty, though their absolute uncertainty was quite small (generally less than 3 MgC + +ha−1). Here, biomass estimates of sparse woody vegetation were primarily responsible for heightened +relative uncertainty. High relative and absolute BGBC uncertainty were also associated with +predictions in select mountainous forests (e.g. east central Chile) as well as forested areas +in and around cities. These patterns were largely driven by AGB uncertainty in the GlobBiomass +product.The GlobBiomass global woody AGB map produced by Santoro et al.30 comprises the backbone + +of our integrated products and, with few exceptions, remains largely unchanged in our final +AGBC map. The native version of the GlobBiomass map is accompanied by an error layer describing +the uncertainty of each pixel’s biomass estimate and this too forms the core of our integrated +uncertainty layers. In areas with tree cover, the global average error of GlobBiomass estimates +is 39 Mg ha−1 or 50% with greater relative uncertainty in densely forested areas, along the + +margins of forested expanses like farm fields and cities, and in similar areas with sparse +tree cover.Adding additional grass or crop biomass in complementary proportion to a grid cell’s +tree cover often did not exceed the estimated error of the original GlobBiomass map (Fig. +7). Grid cells exceeding GlobBiomass’s native uncertainty comprise less than 40% of its total +extent. Exceptions were primarily found in grassland and cropland dominated regions where + +tree cover was generally sparse, and, consequently, the herbaceous biomass contribution was +relatively high. Even so, the absolute magnitude of these additions remains somewhat small +(less than 2.3 MgC ha−1 for grassland and 15 MgC ha−1 for cropland).Differences between the +final harmonized AGBC map and GlobBiomass AGBC. GlobBiomass AGB was aggregated to a 300 m +spatial resolution and converted to C density prior to comparison. Negative values indicate + +areas where the new map reports lower values than GlobBiomass while positive value denote +higher estimates.Larger deviations from GlobBiomass were also present in areas of both dryland +Africa and the Arctic tundra biome, where we used independent layers to estimate woody biomass. +In African drylands, GlobBiomass likely underestimates woody biomass by adopting the conservative +FAO definition (DBH > 10 cm), which implicitly omits the relatively small trees and shrubs + +that are common to the region. The Bouvet map of Africa that we used to supplement these estimates +is not bound by this constraint, was developed from region-specific data, and predicts substantially +higher AGB density throughout much of its extent with comparatively high accuracy (RMSE = +17.1 Mg ha−1)35.GlobBiomass also included sporadic biomass estimates throughout much of the +Arctic tundra biome. Trees are generally scarce throughout this biome, which is instead dominated + +by dwarf shrubs and herbaceous forbs and graminoids, so given GlobBiomass’s adherence to FAO +guidelines, its predictions here may be spurious. We thus prioritized the estimates of the +independent model developed specifically to collectively predict biomass of both woody and +herbaceous tundra vegetation. These estimates were generally higher than GlobBiomass but agreed +well with independent validation data from North America (RMSE = 2.9 Mg ha−1)18.While far + +from a perfect comparison, the only other map to comprehensively report global biomass carbon +density for all landcover types is the IPCC Tier-1 map for the year 2000 by Ruesch and Gibbs28. +As previously described, this map was produced using an entirely different method (“stratify +and multiply”) and distinct data sources23 and represents an earlier epoch. However, the map +is widely used for myriad applications, and it may thus be informative to assess notable differences + +between it and our new products.Ruesch and Gibbs28 report total living C stocks of 345 petagrams +(PgC) in AGBC and 133 PgC in BGBC for a total of 478 PgC, globally. Our estimates are lower +at 287 PgC and 122 PgC in global AGBC and BGBC, respectively, for a total of 409 PgC in living +global vegetation biomass. Herbaceous biomass in our maps comprised 9.1 and 28.3 PgC of total +AGBC and BGBC, respectively. Half of all herbaceous AGBC (4.5 PgC) and roughly 6% of all herbaceous + +BGBC (1.7 PgC) was found in croplands. Moreover, we mapped 22.3 and 6.1 PgC, respectively, +in the AGB and BGB of trees located within the cropland extent. These trees constituted roughly +7% of all global biomass C and are likely overlooked by both the Ruesch and Gibbs map28 and +by remotely sensed forest C maps that are masked to forested areas. Zomer et al.17 first highlighted +this potential discrepancy in the Ruesch and Gibbs map28 when they produced a remarkably similar + +estimate of 34.2 Pg of overlooked C in cropland trees using Tier-1 defaults. However, their +estimates were assumed to be in addition to the 474 PgC originally mapped by Ruesch and Gibbs28. +Here, we suggest that the 28.4 PgC we mapped in cropland trees is already factored into our +409 PgC total.Our AGBC product predicts substantially less biomass C than Ruesch and Gibbs28 +throughout most of the pantropical region and, to a lesser extent, southern temperate forests + +(Fig. 8a). This pattern has been noted by others comparing the Ruesch and Gibbs map28 to other +satellite-based biomass maps73 and may suggest that the IPCC default values used to create +it23 are spatially biased. In addition, well-defined areas of high disagreement emerge in +Africa that directly correspond with the FAO boundaries of the “tropical moist deciduous forest” +ecofloristic zone and suggest that this area, in particular, may merit critical review. Moreover, + +the opposite pattern is observed in this same ecofloristic zone throughout South America. +Our map also predicts greater AGBC throughout much of the boreal forest as well as in African +shrublands and the steppes of South America.Differences between the 2010 harmonized global +maps of above and belowground biomass carbon density and those of the IPCC Tier-1 product +by Ruesch and Gibbs for 2000. Comparisons of AGBC (a) and BGBC (b) maps are shown separately. + +Negative values indicate that the circa 2010 estimates are comparatively lower while positive +values indicate higher estimates.We observed similar, though less pronounced discrepancies, +when comparing BGBC maps (Fig. 8b). Notably, our map predicts substantially more BGBC throughout +the tundra biome – a previously underappreciated C stock that has recently risen to prominance74 +– the boreal forest, African shrublands and most of South America and Australia. However, + +we predict less BGBC in nearly all rainforests (Temperate and Tropical). These differences +and their distinct spatial patterns correspond with the vegetation strata used to make the +IPCC Tier-1 map28 and suggest that the accuracy of the “stratify and multiply” method depends +heavily upon the quality of the referenced and spatial data considered. Inaccuracies in these +data may, in turn, lead to false geographies. Integrating, continuous spatial estimates that + +better capture local and regional variation, as we have done, may thus greatly improve our +understanding of global carbon geographies and their role in the earth system.The error and +variance between our woody biomass estimates – when aggregated to the country level – and +comparable totals reported in the FRA were less for comparisons made against FRA estimates +generated using higher tier IPCC methodologies than for those based on Tier-1 approaches (Fig. + +9). Across the board for AGBC, BGBC, and total C comparisons, the relative RMSE (RMSECV) of +our estimates, when compared to estimates generated using high tier methods, was roughly half +of that obtained from comparisons with Tier-1 estimates (Table 8). Likewise, the coefficient +of determination (R2) was greatest for comparisons with Tier-3 estimates. For each pool-specific +comparison (AGBC, BGBC, and total C), the slopes of the relationships between Tier-1, 2, and + +3 estimates were neither significantly different from a 1:1 relationship nor from one another +(p > 0.05; ANCOVA). Combined, these results suggest that our maps lead to C stock estimates +congruent with those attained from independent, higher-tier reporting methodologies.Comparison +of woody biomass density estimates to corresponding estimates of the FAO’s FRA and the USFS’s +FIA. National woody AGBC totals derived from the woody components of our harmonized maps are + +compared to national totals reported in the 2015 FRA62 (a) in relation to the IPCC inventory +methodology used by each country. Likewise, we derived woody AGBC totals for US states and +compared them to the corresponding totals reported by the 2014 FIA75 (b), a Tier-3 inventory. +We also show the additional effect of considering non-woody C – as is reported in our harmonized +maps – in light green. Similar comparisons were made between our woody BGBC estimates and + +the corresponding estimates of both the FRA (c) and FIA (d). We further summed our woody AGBC +and BGBC estimates and compared them to the total woody C stocks reported by both the FRA +(e) and FIA (f).To explore this association at a finer regional scale, we also compared our +woody C estimates to the United States Forest Service’s Forest Inventory Analysis75 (FIA) +and found similarly strong congruence for AGBC and Total C stocks but subtle overestimates + +for BGBC (Fig. 9). The FIA is a Tier-3 inventory of woody forest biomass C stocks that is +based on extensive and statistically rigorous field sampling and subsequent upscaling, We +used data available at the state level for the year 2014 – again, the only year in which we +could obtain data partitioned by AGBC and BGBC. Like our FRA comparison, we found a tight +relationship between our woody AGBC totals and those reported by the FIA (Fig. 9b; RMSECV + += 25.7%, R2 = 0.960, slope = 1.10, n = 48). Our woody BGBC estimates, though, were systematically +greater than those reported by the FIA (Fig. 9d; RMSECV = 86.4%, R2 = 0.95, slope = 1.51, +n = 48). This trend has been noted by others27 and suggests that the global model that we +used to estimate woody BGBC may not be appropriate for some finer scale applications as is +foretold by the elevated uncertainty reported in our corresponding uncertainty layer (Fig. + +5b). Our total woody C (AGBC + BGBC) estimates (Fig. 9f), however, agreed well with the FIA +(RMSECV = 34.1%, R2 = 0.961, slope = 1.17, n = 48) and thus reflect the outsized contribution +of AGBC to the total woody C stock. When the contribution of herbaceous C stocks is further +added to these comparisons, our stock estimates intuitively increase in rough proportion to +a state’s proportional extent of herbaceous cover. The effect of this addition is particularly + +pronounced for BGBC estimates due to the large root-to-shoot ratios of grassland vegetation.The +relative congruence of our results with higher-tier stock estimates suggests that our maps +could be used to facilitate broader adoption of higher-tier methods among countries currently +lacking the requisite data and those seeking to better account for C in non-woody biomass. +This congruence spans a comprehensive range of biophysical conditions and spatial scales ranging + +from small states to large nations. Moreover, a recent study suggests that the fidelity of +the underlying GlobBiomass AGB map may extend to even finer scales31. While our BGBC estimates +may differ from some fine-scale estimates (Fig. 9d), their tight agreement with high tier +BGBC totals at the national level (Fig. 9c) suggests that they may still be well suited for +many national-scale C inventories – especially for countries lacking requisite high tier data. + +Use of our maps is unlikely to introduce error in excess of that currently implicit in Tier-1 +estimates. Credence, though, should be given to the associated uncertainty estimates. To facilitate +wider adoption of higher-tier methodologies, our maps could be used to derive new, region-specific +default values for use in Tier-2 frameworks76 or to either represent or calibrate 2010 baseline +conditions in Tier-3 frameworks. In so doing, inventories and studies alike could more accurately + +account for the nuanced global geographies of biomass C.These maps are intended for global +applications in which continuous spatial estimates of live AGBC and/or BGBC density are needed +that span a broad range of vegetation types and/or require estimates circa 2010. They are +loosely based upon and share the spatial resolution of the ESA CCI Landcover 2010 map37, which +can be used to extract landcover specific C totals. However, our products notably do not account + +for C stored in non-living C pools like litter or coarse woody debris, nor soil organic matter, +though these both represent large, additional ecosystem C stocks77,78,79. Our maps are explicitly +intended for global scale applications seeking to consider C in the collective living biomass +of multiple vegetation types. For global scale applications focused exclusively on the C stocks +of a single vegetation type, we strongly encourage users to instead use the respective input + +map or model referenced in Table 1 to avoid potential errors that may have been introduced +by our harmonization procedure. For AGB applications over smaller extents, users should further +consider whether locally specific products are available. If such maps are not available and +our maps are considered instead, credence should be given to their pixel-level uncertainty +estimates. As mentioned above, the biomass of shrublands was only explicitly accounted for + +in Africa and the Arctic tundra, since neither broad-scale maps nor models generalizable to +other areas were available in the existing literature. As such, we caution against the use +of our maps outside of these areas when shrubland biomass is of particular interest or importance. +Moreover, in contrast to the estimates for all other vegetation types considered, which we +upscaled to a 300 m resolution, cropland C estimates were largely based on relatively coarse + +8 km resolution data that were downscaled using bilinear resampling to achieve a 300 m spatial +resolution. As such, these estimates may not adequately capture the underlying finer-scale +spatial variation and should be interpreted with that in mind. Likewise, we reiterate that +some BGBC estimates may differ from locally derived Tier-3 estimates, and attention should +thus be given to our reported pixel-level uncertainty for all applications. Finally, our maps + +should not be used in comparison with the IPCC Tier-1 map of Ruesch and Gibbs (2008) to detect +biomass change between the two study periods due to significant methodological differences +between these products.Cropland biomass maps were created in the R statistical computing environment80. +All other coding was done in Google Earth Engine81 (GEE), wherein our workflow consisted of +18 interconnected scripts. All code can be found on GitHub (https://github.com/sethspawn/globalBiomassC) + +and permanently archived by Zenodo82.Houghton, R. A., Hall, F. & Goetz, S. J. Importance of +biomass in the global carbon cycle. J. Geophys. Res. Biogeosciences 114 (2009).Huntzinger, +D. N. et al. The North American Carbon Program Multi-Scale Synthesis and Terrestrial Model +Intercomparison Project – Part 1: Overview and experimental design. Geosci. Model Dev 6, 2121–2133 +(2013).Article ADS Google Scholar Schwalm, C. R. et al. Toward “optimal” integration of terrestrial + +biosphere models. Geophys. Res. Lett. 42, 4418–4428 (2015).Article ADS Google Scholar Li, +W. et al. Land-use and land-cover change carbon emissions between 1901 and 2012 constrained +by biomass observations. Biogeosciences 14, 5053–5067 (2017).Article Google Scholar Spawn, +S. A., Lark, T. J. & Gibbs, H. K. Carbon emissions from cropland expansion in the United States. +Environ. Res. Lett. 14, 045009 (2019).Article CAS ADS Google Scholar Harris, N. L. et al. + +Baseline Map of Carbon Emissions from Deforestation in Tropical Regions. Science 336, 1573–1576 +(2012).Article CAS PubMed ADS Google Scholar Baccini, A. et al. Tropical forests are a net +carbon source based on aboveground measurements of gain and loss. Science 358, 230–234 (2017).Article +MathSciNet CAS PubMed MATH ADS Google Scholar Strassburg, B. B. N. et al. Global congruence +of carbon storage and biodiversity in terrestrial ecosystems. Conserv. Lett 3, 98–105 (2010).Article + +Google Scholar West, P. C. et al. Trading carbon for food: Global comparison of carbon stocks +vs. crop yields on agricultural land. Proc. Natl. Acad. Sci. 107, 19645–19648 (2010).Article +CAS PubMed ADS PubMed Central Google Scholar Carvalhais, N. et al. Global covariation of carbon +turnover times with climate in terrestrial ecosystems. Nature 514, 213–217 (2014).Article +CAS PubMed ADS Google Scholar BrandĂŁo, A. et al. Estimating the Potential for Conservation + +and Farming in the Amazon and Cerrado under Four Policy Scenarios. Sustainability 12, 1277 +(2020).Article Google Scholar Gibbs, H. K., Brown, S., Niles, J. O. & Foley, J. A. Monitoring +and estimating tropical forest carbon stocks: making REDD a reality. Environ. Res. Lett. 2, +045023 (2007).Article ADS CAS Google Scholar Fargione, J. E. et al. Natural climate solutions +for the United States. Sci. Adv. 4, eaat1869 (2018).Article PubMed PubMed Central ADS Google + +Scholar Griscom, B. W. et al. Natural climate solutions. Proc. Natl. Acad. Sci. 114, 11645–11650 +(2017).Article CAS PubMed ADS PubMed Central Google Scholar Goetz, S. J. et al. Mapping and +monitoring carbon stocks with satellite observations: a comparison of methods. Carbon Balance +Manag 4, 2 (2009).Article PubMed PubMed Central CAS Google Scholar Xiao, J. et al. Remote +sensing of the terrestrial carbon cycle: A review of advances over 50 years. Remote Sens. + +Environ. 233, 111383 (2019).Article ADS Google Scholar Zomer, R. J. et al. Global Tree Cover +and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national +carbon budgets. Sci. Rep 6, 29987 (2016).Article CAS PubMed PubMed Central ADS Google Scholar +Berner, L. T., Jantz, P., Tape, K. D. & Goetz, S. J. Tundra plant above-ground biomass and +shrub dominance mapped across the North Slope of Alaska. Environ. Res. Lett. 13, 035002 (2018).Article + +ADS Google Scholar Xia, J. et al. Spatio-Temporal Patterns and Climate Variables Controlling +of Biomass Carbon Stock of Global Grassland Ecosystems from 1982 to 2006. Remote Sens 6, 1783–1802 +(2014).Article ADS Google Scholar Monfreda, C., Ramankutty, N. & Foley, J. A. Farming the +planet: 2. Geographic distribution of crop areas, yields, physiological types, and net primary +production in the year 2000. Glob. Biogeochem. Cycles 22, GB1022 (2008).Article ADS CAS Google + +Scholar Wolf, J. et al. Biogenic carbon fluxes from global agricultural production and consumption. +Glob. Biogeochem. Cycles 29, 1617–1639 (2015).Article CAS ADS Google Scholar Mokany, K., Raison, +R. J. & Prokushkin, A. S. Critical analysis of root: shoot ratios in terrestrial biomes. Glob. +Change Biol. 12, 84–96 (2006).Article ADS Google Scholar IPCC 2006. 2006 IPCC Guidelines for +National Greenhouse Gas Inventories. vol. 4 (IPCC National Greenhouse Gas Inventories Programme, + +2006).IPCC 2019. 2019 Refinement to the 2006 IPCC Guidlines for National Greenhouse Gas Inventories. +vol. 4 (IPCC National Greenhouse Gas Inventories Programme, 2019).Reich, P. B. et al. Temperature +drives global patterns in forest biomass distribution in leaves, stems, and roots. Proc. Natl. +Acad. Sci. 111, 13721–13726 (2014).Article CAS PubMed ADS PubMed Central Google Scholar Wang, +P. et al. Belowground plant biomass allocation in tundra ecosystems and its relationship with + +temperature. Environ. Res. Lett. 11, 055003 (2016).Article ADS CAS Google Scholar Russell, +M. B., Domke, G. M., Woodall, C. W. & D’Amato, A. W. Comparisons of allometric and climate-derived +estimates of tree coarse root carbon stocks in forests of the United States. Carbon Balance +Manag 10, 20 (2015).Article PubMed PubMed Central CAS Google Scholar Ruesch, A. & Gibbs, H. +New IPCC Tier-1 Global Biomass Carbon Map for the Year 2000. Carbon Dioxide Information Analysis + +Center, Oak Ridge National Laboratory, http://cdiac.ess-dive.lbl.gov (2008).Schimel, D. et +al. Observing terrestrial ecosystems and the carbon cycle from space. Glob. Change Biol. 21, +1762–1776 (2015).Article ADS Google Scholar Santoro, M. et al. GlobBiomass - global datasets +of forest biomass. PANGAEA https://doi.org/10.1594/PANGAEA.894711 (2018).Huang, W. et al. +High-Resolution Mapping of Aboveground Biomass for Forest Carbon Monitoring System in the + +3 Tri-State Region of Maryland, Pennsylvania and Delaware, USA. Environ. Res. Lett. 14, 095002 +(2019).Article ADS Google Scholar Food and Agricultural Organization. FRA 2015 Terms and Definitions. +(Food and Agricultural Organization of the United Nations, 2012).Quegan, S. et al. DUE GlobBiomass: +D6 - Global Biomass Map Algorithm Theoretical Basis Document. GlobBiomass, http://globbiomass.org/wp-content/uploads/DOC/Deliverables/D6_D7/GlobBiomass_D6_7_Global_ATBD_v2.pdf +(2017).Hansen, M. C. et al. High-Resolution Global Maps of 21st-Century Forest Cover Change. + +Science 342, 850–853 (2013).Article CAS PubMed ADS Google Scholar Bouvet, A. et al. An above-ground +biomass map of African savannahs and woodlands at 25 m resolution derived from ALOS PALSAR. +Remote Sens. Environ. 206, 156–173 (2018).Article ADS Google Scholar Le Toan, T., Beaudoin, +A., Riom, J. & Guyon, D. Relating forest biomass to SAR data. IEEE Trans. Geosci. Remote Sens +30, 403–411 (1992).Article ADS Google Scholar European Space Agency. 300 m Annual global land + +cover time series from 1992 to 2015. European Space Agency - Climate Change Initiative, http://maps.elie.ucl.ac.be/CCI/viewer/download.php +(2017).BartholomĂ©, E. & Belward, A. S. GLC2000: a new approach to global land cover mapping +from Earth observation data. Int. J. Remote Sens. 26, 1959–1977 (2005).Article ADS Google +Scholar Avitabile, V. et al. An integrated pan-tropical biomass map using multiple reference +datasets. Glob. Change Biol. 22, 1406–1420 (2016).Article ADS Google Scholar Englund, O. et + +al. A new high-resolution nationwide aboveground carbon map for Brazil. Geo Geogr. Environ. +4, e00045 (2017).Article Google Scholar Scholze, M., Buchwitz, M., Dorigo, W., Guanter, L. +& Quegan, S. Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon +cycle data assimilation systems. Biogeosciences 14, 3401–3429 (2017).Article CAS ADS Google +Scholar Martin, A. R., Doraisami, M. & Thomas, S. C. Global patterns in wood carbon concentration + +across the world’s trees and forests. Nat. Geosci. 11, 915 (2018).Article CAS ADS Google Scholar +Kottek, M., Grieser, J., Beck, C., Rudolf, B. & Rubel, F. World Map of the Köppen-Geiger climate +classification updated. Meteorol. Z. 15, 259–263 (2006).Article Google Scholar Olofsson, P. +et al. Good practices for estimating area and assessing accuracy of land change. Remote Sens. +Environ. 148, 42–57 (2014).Article ADS Google Scholar Berner, L. T., Jantz, P., Tape, K. D. + +& Goetz, S. J. ABoVE: Gridded 30-m Aboveground Biomass, Shrub Dominance, North Slope, AK, +2007–2016. Oak Ridge National Laboratory Distributed Active Archive Center https://doi.org/10.3334/ORNLDAAC/1565 +(2018).Vermote, E. F. & Wolfe, R. MYD09GQ MODIS/Aqua Surface Reflectance Daily L2G Global +250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MYD09GQ.006 +(2015).Vermote, E. F. & Wolfe, R. MOD09GQ MODIS/Terra Surface Reflectance Daily L2G Global + +250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MOD09GQ.006 +(2015).Steven, M. D., Malthus, T. J., Baret, F., Xu, H. & Chopping, M. J. Intercalibration +of vegetation indices from different sensor systems. Remote Sens. Environ. 88, 412–422 (2003).Article +ADS Google Scholar Adler, P. B. et al. Productivity Is a Poor Predictor of Plant Species Richness. +Science 333, 1750–1753 (2011).Article CAS PubMed ADS Google Scholar Didan, K. MYD13Q1 MODIS/Aqua + +Vegetation Indices 16-Day L3 Global 250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed +Active Archive Center, https://doi.org/10.5067/MODIS/MYD13Q1.006 (2015).Didan, K. MOD13Q1 +MODIS/Terra Vegetation Indices 16-Day L3 Global 250 m SIN Grid V006. NASA EOSDIS Land Processes +Distributed Active Archive Center https://doi.org/10.5067/MODIS/MOD13Q1.006 (2015).Fensholt, +R. & Proud, S. R. Evaluation of Earth Observation based global long term vegetation trends + +— Comparing GIMMS and MODIS global NDVI time series. Remote Sens. Environ. 119, 131–147 (2012).Article +ADS Google Scholar Li, Z. et al. Comparing cropland net primary production estimates from +inventory, a satellite-based model, and a process-based model in the Midwest of the United +States. Ecol. Model. 277, 1–12 (2014).Article Google Scholar Turner, D. P. et al. Evaluation +of MODIS NPP and GPP products across multiple biomes. Remote Sens. Environ. 102, 282–292 (2006).Article + +ADS Google Scholar Ramankutty, N., Evan, A. T., Monfreda, C. & Foley, J. A. Farming the planet: +1. Geographic distribution of global agricultural lands in the year 2000. Glob. Biogeochem. +Cycles 22, GB1003 (2008).Grassini, P., Eskridge, K. M. & Cassman, K. G. Distinguishing between +yield advances and yield plateaus in historical crop production trends. Nat. Commun. 4, 2918 +(2013).Article PubMed ADS CAS Google Scholar Gray, J. M. et al. Direct human influence on + +atmospheric CO2 seasonality from increased cropland productivity. Nature 515, 398–401 (2014).Article +CAS PubMed ADS Google Scholar Running, S. W., Mu, Q. & Zhao, M. MOD17A3H MODIS/Terra Net Primary +Production Yearly L4 Global 1 km SIN Grid V055. NASA EOSDIS Land Processes Distributed Active +Archive Center, https://lpdaac.usgs.gov/products/mod17a3v055/ (2015).Fick, S. & Hijmans, R. +WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas. Int. J. Climatol. + +37, 4302–4315 (2017).Article Google Scholar Potapov, P. et al. The last frontiers of wilderness: +Tracking loss of intact forest landscapes from 2000 to 2013. Sci. Adv. 3, e1600821 (2017).Article +PubMed PubMed Central ADS Google Scholar Harris, N. L., Goldman, E. D. & Gibbes, S. Spatial +Database of Planted Trees (SDPT Version 1.0). World Resources Institute, https://www.wri.org/publication/planted-trees +(2019).Food and Agricultural Organization. Global Forest Resources Assessment 2015: Desk Reference. + +(Food and Agricultural Organization of the United Nations, 2015).Dimiceli, C. et al. MOD44B +MODIS/Terra Vegetation Continuous Fields Yearly L3 Global 250 m SIN Grid V006. NASA EOSDIS +Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MOD44B.006 +(2015).Sexton, J. O. et al. Global, 30-m resolution continuous fields of tree cover: Landsat-based +rescaling of MODIS vegetation continuous fields with lidar-based estimates of error. Int. + +J. Digit. Earth 6, 427–448 (2013).Article ADS Google Scholar Dinerstein, E. et al. An Ecoregion-Based +Approach to Protecting Half the Terrestrial Realm. BioScience 67, 534–545 (2017).Article PubMed +PubMed Central Google Scholar Spawn, S. A. & Gibbs, H. K. Global Aboveground and Belowground +Biomass Carbon Density Maps for the Year 2010. Oak Ridge National Laboratory Distributed Active +Archive Center, https://doi.org/10.3334/ORNLDAAC/1763 (2019).Spawn, S. A., Sullivan, C. C., + +Lark, T. J. & Gibbs, H. K. Harmonized global maps of above and belowground biomass carbon +density in the year 2010. figshare https://doi.org/10.6084/m9.figshare.c.4561940 (2020).Gao, +Q. et al. Climatic change controls productivity variation in global grasslands. Sci. Rep 6, +26958 (2016).Article CAS PubMed PubMed Central ADS Google Scholar de Jong, R., Verbesselt, +J., Schaepman, M. E. & de Bruin, S. Trend changes in global greening and browning: contribution + +of short-term trends to longer-term change. Glob. Change Biol 18, 642–655 (2012).Article ADS +Google Scholar Gonsamo, A., Chen, J. M. & Lombardozzi, D. Global vegetation productivity response +to climatic oscillations during the satellite era. Glob. Change Biol. 22, 3414–3426 (2016).Article +ADS Google Scholar Ray, D. K. et al. Climate change has likely already affected global food +production. Plos One 14, e0217148 (2019).Article CAS PubMed PubMed Central Google Scholar + +Lobell, D. B., Schlenker, W. & Costa-Roberts, J. Climate Trends and Global Crop Production +Since 1980. Science 333, 616–620 (2011).Article CAS PubMed ADS Google Scholar Hu, T. et al. +Mapping Global Forest Aboveground Biomass with Spaceborne LiDAR, Optical Imagery, and Forest +Inventory Data. Remote Sens 8, 565 (2016).Article ADS Google Scholar Iversen, C. M. et al. +The unseen iceberg: plant roots in arctic tundra. New Phytol. 205, 34–58 (2015).Article PubMed + +Google Scholar USDA Forest Service. Forest Inventory and Analysis National Program: Standard +Tables of Forest Caron Stock Estimates by State. Forest Inventory and Analysis National Program, +https://www.fia.fs.fed.us/forestcarbon/index.php (2014).Langner, A., Achard, F. & Grassi, +G. Can recent pan-tropical biomass maps be used to derive alternative Tier 1 values for reporting +REDD + activities under UNFCCC? Environ. Res. Lett. 9, 124008 (2014).Article ADS Google Scholar + +JobbĂĄgy, E. G. & Jackson, R. B. The Vertical Distribution of Soil Organic Carbon and Its Relation +to Climate and Vegetation. Ecol. Appl. 10, 423–436 (2000).Article Google Scholar Scharlemann, +J. P., Tanner, E. V., Hiederer, R. & Kapos, V. Global soil carbon: understanding and managing +the largest terrestrial carbon pool. Carbon Manag 5, 81–91 (2014).Article CAS Google Scholar +Domke, G. M., Woodall, C. W., Walters, B. F. & Smith, J. E. From Models to Measurements: Comparing + +Downed Dead Wood Carbon Stock Estimates in the U.S. Forest Inventory. Plos One 8, e59949 (2013).Article +CAS PubMed PubMed Central ADS Google Scholar R Core Team. R: A Language and Environment for +Statistical Computing, https://www.R-project.org/ (2017).Gorelick, N. et al. Google Earth +Engine: Planetary-scale geospatial analysis for everyone. Remote Sens. Environ. 202, 18–27 +(2017).Article ADS Google Scholar Spawn, S. A. sethspawn/globalBiomassC. Zenodo https://doi.org/10.5281/zenodo.3647567 + +(2020).Olson, D. M. et al. Terrestrial Ecoregions of the World: A New Map of Life on EarthA +new global map of terrestrial ecoregions provides an innovative tool for conserving biodiversity. +BioScience 51, 933–938 (2001).European Space Agency. Land Cover CCI Product User Guide Version +2, D3.4-PUG, v2.5. European Space Agency - Climate Change Initiative, http://maps.elie.ucl.ac.be/CCI/viewer/download/ESACCI-LC-PUG-v2.5.pdf +(2016).Friedl, M. A. & Sulla-Menashe, D. MCD12Q1 MODIS/Terra + Aqua Land Cover Type Yearly + +L3 Global 500 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, +https://doi.org/10.5067/MODIS/MCD12Q1.006 (2019).Jing, Q., BĂ©langer, G., Baron, V. & Bonesmo, +H. Modeling the Biomass and Harvest Index Dynamics of Timothy. Agron. J. 103, 1397–1404 (2011).Article +Google Scholar West, T. O. et al. Cropland carbon fluxes in the United States: increasing +geospatial resolution of inventory-based carbon accounting. Ecol. Appl. 20, 1074–1086 (2010).Article + +PubMed Google Scholar Unkovich, M., Baldock, J. & Forbes, M. Variability in harvest index +of grain crops and potential significance for carbon accounting: examples from Australian +agriculture. Adv. Agron 105, 173–219 (2010).Article Google Scholar Hay, R. K. M. Harvest index: +a review of its use in plant breeding and crop physiology. Ann. Appl. Biol. 126, 197–216 (1995).Article +Google Scholar Larcher, W. Physiological Plant Ecology: Ecophysiology and Stress Physiology + +of Functional Groups. (Springer-Verlag, 2003).Hakala, K., Keskitalo, M. & Eriksson, C. Nutrient +uptake and biomass accumulation for eleven different field crops. Agric. Food Sci 18, 366–387 +(2009).Article CAS Google Scholar Bolinder, M. A., Janzen, H. H., Gregorich, E. G., Angers, +D. A. & VandenBygaart, A. J. An approach for estimating net primary productivity and annual +carbon inputs to soil for common agricultural crops in Canada. Agric. Ecosyst. Environ 118, + +29–42 (2007).Article Google Scholar Mackenzie, B. A. & Van Fossen, L. Managing Dry Grain In +Storage. In Agricultural Engineers’ Digest vol. 20 (Purdue University Cooperative Extension +Service, 1995).Goodwin, M. Crop Profile for Dry Bean in Canada. Agriculture and Agri-Food +Canada, http://publications.gc.ca/collections/collection_2009/agr/A118-10-4-2005E.pdf (2005).Schulte +auf’m Erley, G., Kaul, H.-P., Kruse, M. & Aufhammer, W. Yield and nitrogen utilization efficiency + +of the pseudocereals amaranth, quinoa, and buckwheat under differing nitrogen fertilization. +Eur. J. Agron. 22, 95–100 (2005).Article CAS Google Scholar Bjorkman, T. Northeast Buckwheat +Growers Newsletter No. 19. Cornell University NYSAES, http://www.hort.cornell.edu/bjorkman/lab/buck/NL/june05.php +(2005).Kyle, G. P. et al. GCAM 3.0 Agriculture and Land Use: Data Sources and Methods, https://doi.org/10.2172/1036082 +(2011).Bastin, S. & Henken, K. Water Content of Fruits and Vegetables. University of Kentucky + +Cooperative Extension Service, https://www.academia.edu/5729963/Water_Content_of_Fruits_and_Vegetables +(1997).Smil, V. Crop Residues: Agriculture’s Largest HarvestCrop residues incorporate more +than half of the world’s agricultural phytomass. BioScience 49, 299–308 (1999).Article Google +Scholar Squire, G. R. The physiology of tropical crop production. (C.A.B. International, 1990).Williams, +J. R. et al. EPIC users guide v. 0509. Texas A & M University Blackland Research and Extension + +Center, http://epicapex.tamu.edu/files/2013/02/epic0509usermanualupdated.pdf (2006).Okeke, +J. E. Cassava varietal improvement for processing and utilization in livestock feeds. In Cassava +as Livestock Feed in Africa (International Institute of Tropical Agriculture, 1992).Pongsawatmanit, +R., Thanasukarn, P. & Ikeda, S. Effect of Sucrose on RVA Viscosity Parameters, Water Activity +and Freezable Water Fraction of Cassava Starch Suspensions. ScienceAsia 28, 129–134 (2002).Article + +CAS Google Scholar Gigou, J. et al. Fonio Millet (Digitaria Exilis) Response to N, P and K +Fertilizers Under Varying Climatic Conditions in West. AFRICA. Exp. Agric 45, 401–415 (2009).Article +Google Scholar Food and Agricultural Organization. FAOSTAT 2001: FAO statistical databasees. +FAOSTAT, http://www.fao.org/faostat/en/#data (2006).Bolinder, M. A., Angers, D. A., BĂ©langer, +G., Michaud, R. & LaverdiĂšre, M. R. Root biomass and shoot to root ratios of perennial forage + +crops in eastern Canada. Can. J. Plant Sci. 82, 731–737 (2002).Article Google Scholar Deferne, +J. & Pate, D. W. Hemp seed oil: A source of valuable essential fatty acids. J. Int. Hemp Assoc +3, 4–7 (1996). Google Scholar Islam, Md. R. et al. Study of Harvest Index and Genetic Variability +in White Jute (Corchorus capsularis) Germplasm. J. Biol. Sci. 2, 358–360 (2002).Article Google +Scholar Ahad, A. & Debnath, C. N. Shoot Root Ratio of Jute Varieties and the Nature of Association + +Between Root Characteristics and the Yield of Dry Matter and Fiber. Bangladesh J. Agric. Res +13, 17–22 (1988). Google Scholar Mondal, S. S., Ghosh, A. & Debabrata, A. Effect of seeding +time of linseed (Linum usitatissimum) in rice (Oryza sativa)-based paira cropping system under +rainfed lowland condition. Indian J. Agric. Sci 75, 134–137 (2005). Google Scholar Ayaz, S., +Moot, D. J., Mckenzie, B. A., Hill, G. D. & Mcneil, D. L. The Use of a Principal Axis Model + +to Examine Individual Plant Harvest Index in Four Grain Legumes. Ann. Bot. 94, 385–392 (2004).Article +CAS PubMed PubMed Central Google Scholar Goudriaan, J. & Van Laar, H. H. Development and growth. +In Modelling Potential Crop Growth Processes: Textbook with Exercises (eds. Goudriaan, J. +& Van Laar, H. H.) 69–94 (Springer Netherlands, 1994).National Research Council. Nutrient +Requirements of Nonhuman Primates: Second Revised Edition. (The National Academies Press, + +2003).Roth, C. M., Shroyer, J. P. & Paulsen, G. M. Allelopathy of Sorghum on Wheat under Several +Tillage Systems. Agron. J. 92, 855–860 (2000).Article Google Scholar Heidari Zooleh, H. et +al. Effect of alternate irrigation on root-divided Foxtail Millet (Setaria italica). Aust. +J. Crop Sci 5, 205–2013 (2011). Google Scholar BrĂŒck, H., Sattelmacher, B. & Payne, W. A. +Varietal differences in shoot and rooting parameters of pearl millet on sandy soils in Niger. + +Plant Soil 251, 175–185 (2003).Article Google Scholar Oelke, E. A., Putnam, D. H., Teynor, +T. M. & Oplinger, E. S. Quinoa. In Alternative Field Crops Manual (University of Wisconsin-Extension, +Cooperative Extension, 1992).Robertson, M. J., Silim, S., Chauhan, Y. S. & Ranganathan, R. +Predicting growth and development of pigeonpea: biomass accumulation and partitioning. Field +Crops Res 70, 89–100 (2001).Article Google Scholar Armstrong, E. Desiccation & harvest of + +field peas. In Pulse management in Southern New South Wales (State of New South Wales Agriculture, +1999).Fischer, R. A. (Tony) & Edmeades, G. O. Breeding and Cereal Yield Progress. Crop Sci. +50, S-85–S-98 (2010).Article Google Scholar Atlin, G. N. et al. Developing rice cultivars +for high-fertility upland systems in the Asian tropics. Field Crops Res 97, 43–52 (2006).Article +Google Scholar Bueno, C. S. & Lafarge, T. Higher crop performance of rice hybrids than of + +elite inbreds in the tropics: 1. Hybrids accumulate more biomass during each phenological +phase. Field Crops Res 112, 229–237 (2009).Article Google Scholar Yang, J. & Zhang, J. Crop +management techniques to enhance harvest index in rice. J. Exp. Bot 61, 3177–3189 (2010).Article +CAS PubMed Google Scholar Ziska, L. H., Namuco, O., Moya, T. & Quilang, J. Growth and Yield +Response of Field-Grown Tropical Rice to Increasing Carbon Dioxide and Air Temperature. Agron. + +J. 89, 45–53 (1997).Article Google Scholar Mwaja, V. N., Masiunas, J. B. & Weston, L. A. Effects +of fertility on biomass, phytotoxicity, and allelochemical content of cereal rye. J. Chem. +Ecol. 21, 81–96 (1995).Article CAS PubMed Google Scholar Bruinsma, J. & Schuurman, J. J. The +effect of spraying with DNOC (4,6-dinitro-o-cresol) on the growth of the roots and shoots +of winter rye plants. Plant Soil 24, 309–316 (1966).Article CAS Google Scholar Yau, S. K., + +Sidahmed, M. & Haidar, M. Conservation versus Conventional Tillage on Performance of Three +Different Crops. Agron. J. 102, 269–276 (2010).Article Google Scholar Hojati, M., Modarres-Sanavy, +S. A. M., Karimi, M. & Ghanati, F. Responses of growth and antioxidant systems in Carthamustinctorius +L. under water deficit stress. Acta Physiol. Plant. 33, 105–112 (2011).Article Google Scholar +Oelke, E. A. et al. Safflower. In Alternative Field Crops Manual (University of Wisconsin-Extension, + +Cooperative Extension, 1992).Perez, R. Chapter 3: Sugar cane. In Feeding pigs in the tropics +(Food and Agricultural Organization of the United Nations, 1997).Van Dillewijn, C. Botany +of Sugarcane. (Chronica Botanica Co, 1952).Pate, F. M., Alvarez, J., Phillips, J. D. & Eiland, +B. R. Sugarcane as a Cattle Feed: Production and Utilization. (University of Florida Extension +Institute of Food and Agricultural Sciences, 2002).Download referencesWe gratefully acknowledge + +all the data producers, without whom this work would not be possible. We especially thank +Maurizio Santoro et al., Alexandre Bouvet et al., Jiangzhou Xia et al., Logan T. Berner et +al., Chad Monfreda et al., and Julie Wolf et al. whose AGB estimates comprise the core of +our harmonized products and, in many cases, whose feedback greatly improved the quality of +their inclusion. We are also grateful to the thoughtful feedback of three anonymous reviewers + +whose suggestions greatly improved the quality of our products and the clarity of our manuscript. +Funding for this project was generously provided by the David and Lucile Packard Foundation +and the National Wildlife Federation.Department of Geography, University of Wisconsin-Madison, +Madison, WI, USASeth A. Spawn, Clare C. Sullivan & Holly K. GibbsCenter for Sustainability +and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University + +of Wisconsin-Madison, Madison, WI, USASeth A. Spawn, Clare C. Sullivan, Tyler J. Lark & Holly +K. GibbsYou can also search for this author in PubMed Google ScholarYou can also search for +this author in PubMed Google ScholarYou can also search for this author in PubMed Google ScholarYou +can also search for this author in PubMed Google ScholarS.A.S. designed the harmonization +procedure, compiled and standardized individual biomass layers, conducted all mapping, and + +led manuscript development. C.C.S., T.J.L. and H.K.G. assisted with conceptualization, and +manuscript development.Correspondence to Seth A. Spawn.The authors declare no competing interests.Publisher’s +note Springer Nature remains neutral with regard to jurisdictional claims in published maps +and institutional affiliations.Open Access This article is licensed under a Creative Commons +Attribution 4.0 International License, which permits use, sharing, adaptation, distribution + +and reproduction in any medium or format, as long as you give appropriate credit to the original +author(s) and the source, provide a link to the Creative Commons license, and indicate if +changes were made. The images or other third party material in this article are included in +the article’s Creative Commons license, unless indicated otherwise in a credit line to the +material. If material is not included in the article’s Creative Commons license and your intended + +use is not permitted by statutory regulation or exceeds the permitted use, you will need to +obtain permission directly from the copyright holder. To view a copy of this license, visit +http://creativecommons.org/licenses/by/4.0/.The Creative Commons Public Domain Dedication +waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files associated +with this article.Reprints and PermissionsSpawn, S.A., Sullivan, C.C., Lark, T.J. et al. Harmonized + +global maps of above and belowground biomass carbon density in the year 2010. Sci Data 7, +112 (2020). https://doi.org/10.1038/s41597-020-0444-4Download citationReceived: 03 July 2019Accepted: +14 February 2020Published: 06 April 2020DOI: https://doi.org/10.1038/s41597-020-0444-4Anyone +you share the following link with will be able to read this content:Sorry, a shareable link +is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing + +initiative Nature Water (2023)Nature Plants (2023)Nature Communications (2023)Scientific Data +(2023)Nature Communications (2023)Advertisement Scientific Data (Sci Data) ISSN 2052-4463 +(online) © 2023 Springer Nature LimitedSign up for the Nature Briefing newsletter — what matters +in science, free to your inbox daily. January 22 - July 26, 2023JPEGOne of the wettest wet +seasons in northern Australia transformed large areas of the country’s desert landscape over + +the course of many months in 2023. A string of major rainfall events that dropped 690 millimeters +(27 inches) between October 2022 and April 2023 made it the sixth-wettest season on record +since 1900–1901.This series of false-color images illustrates the rainfall’s months-long effects +downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and +bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer + +(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), +water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following +weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached +further downstream after another intense period of precipitation in March. This scene shows +that water had filled in some of the north-northwest trending ridges that are part of a vast + +fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. +Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River +and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly +the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed +about every three years; when it reaches especially high levels, it may take 18 months to + +2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding +floodplains support hundreds of thousands of waterbirds and are designated as an Important +Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, +the events of the 2022-2023 rainy season stood out in several ways. They occurred while La +Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern + +Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) +In addition, major rains occurring in succession, as was the case with the January and March +events, have the overall effect of prolonging floods. That’s because vegetation that grows +after the first event slows down the pulse of water that comes through in the next rain event.The +high water has affected both local communities and ecosystems. Floods have inundated cattle + +farms and isolated towns on temporary islands. At the same time, they are a natural feature +of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support +biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS +LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated +heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day + +for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves +off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto +unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under +water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February +5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast + +of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September +18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone +in the Mediterranean inundated cities along the northeastern coast of Libya in early September +2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, +was one of the worst hit by the storm and suffered extensive flooding and damage. On September + +10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end +of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods +triggered two dams along the wadi to collapse. The failure of the second dam, located just +one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the +city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods + +out to sea. The images above show the city before and after the storm. The image on the right, +acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded +banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears +muddier than in the image on the left, which shows the same area on August 25 and was acquired +by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate + +that 3,100 buildings in Derna were damaged by rushing water. According to the UN International +Organization for Migration (IOM), about 40,000 people in the country were displaced by the +storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, +or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in +autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest + +in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution +estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. +NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological +Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city +destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 + +Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting +of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers +out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s +coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland +in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm + +dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. +Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours +in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods +Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While +that may not seem as consequential as, say, record warm sea surface temperatures, the color + +of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, +microscopic photosynthesizing organisms, abound in near-surface waters and are foundational +to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected +under climate change and signals changes to ecosystems within the global ocean, which covers +70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the + +U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has +undergone a significant change in color in the past 20 years. After analyzing ocean color +data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua +satellite, they found that much of the change stems from the ocean turning more green. The +map above highlights the areas where ocean surface color changed between 2002 and 2022, with + +darker shades of green representing more-significant differences (higher signal-to-noise ratio). +By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in +the last 20 years.” The study focused on tropical and subtropical regions, excluding higher +latitudes, which are dark for part of the year, and coastal waters, where the data are naturally +very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s + +surface, where chlorophyll levels also changed over the study period. Chlorophyll has been +the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. +However, those estimates use only a few colors in the visible light spectrum. The values shown +in green are based on the whole gamut of colors and therefore capture more information about +the ecosystem as a whole. A long time series from a single sensor is relatively rare in the + +remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far +exceeding its design life of 6 years—Cael wondered what long term trends could be discovered +in the data. In particular, he was curious what might have been missed in all the ocean color +information it had collected. “There’s more encoded in the data than we actually make use +of,” he said. By going big with the data, the team discerned an ocean color trend that had + +been predicted by climate modeling, but one that was expected to take 30-40 years of data +to detect using satellite-based chlorophyll estimates. That’s because the natural variability +in chlorophyll is high relative to the climate change trend. The new method, incorporating +all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is +difficult to say what exact ecological changes are responsible for the new hues. However, + +the authors posit, they could result from different assemblages of plankton, more detrital +particles, or other organisms such as zooplankton. It is unlikely the color changes come from +materials such as plastics or other pollutants, said Cael, since they are not widespread enough +to register at large scales. “What we do know is that in the last 20 years, the ocean has +become more stratified,” he said. Surface waters have absorbed excess heat from the warming + +climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. +This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean +color change align well with where the sea has become more stratified, said Cael, but there +is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic +ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) + +satellite, set to launch in 2024, will return observations in finer color resolution. The +new data will enable researchers to infer more information about ocean ecology, such as the +diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory +image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two +decades of satellite measurements show that the sea surface is shading toward green.Image + +of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets +from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level +measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image +of the Day Water The use of plastic on farms has become so common in recent decades that there +there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe + +Canary Islands were at the center of a mĂ©lange of natural events in summer 2023. The Moderate +Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage +of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke +is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started +amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities + +issued evacuation orders to five villages, and responders focused on containing the fire’s +spread and protecting residential areas near the coast, according to news reports. Other fires +have burned on the Canary Islands this summer, including on La Palma in July.To the west, +a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the +Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks + +disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert +was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced +in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, +dust sometimes makes it even further west toward Central America and the U.S. states of Florida +and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely + +a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined +from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton +growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. +A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect +that occurs when sunlight reflects off the surface of the water at the same angle that a satellite + +sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA +Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. +Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena +visible from space appeared together in one image.Image of the Day for August 17, 2023 Image +of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility + +was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human +Presence In one frame International Space Station astronauts were able to capture the evolution +of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands +become progressively older to the northwest. As these islands move away from their magma sources +they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary + +Island is suitable for lichen and crops 
 and for training astronauts. Image of the Day Land +The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran +Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour +funnel-shaped estuarine inlets, collectively known as RĂ­as Baixas, line the coast of Galicia, +in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, + +making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, +the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the RĂ­as de Arousa +(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts +of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves +like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and + +hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area + +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story + +by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, +and hundreds of ropes are suspended into the water column from each structure. Mussels attach +to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts +allow for high yields of mussels in a small area of the water. The RĂ­as Baixas are on the +northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings + +colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area +between April and October. Much of the mussel production in the RĂ­as Baixas occurs during +this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported +by upwelling. Spain is the top mussel producing country in the world. RĂ­as de Arousa alone +contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth + +Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story +by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast +are some of the most productive places to grow mussels.Image of the Day for September 19, +2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This +image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere + +Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve +off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust +and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and +an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off +the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay + +18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going +dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling +in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters +(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric +river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 + +(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered +about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other +image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. +Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains +a quarter of the water volume, explained RenĂ© Garreaud, an Earth scientist at the University + +of Chile. Seasonal changes and the influx of water have led to widespread greening of the +landscape around the lake.Researchers have assessed that ongoing development and water use +in the nearby community of Paine, increasing water use by farmers and in homes and pools, +as well as several years of drought, likely contributed to the drawdown of the lake. Annual +rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, + +according to one analysis from a team of researchers from the University of Chile.Before 2010, +the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the +water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how +long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered +substantial precipitation along the high terrain and foothills that have giv­­en us a welcome + +interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can +fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much +longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from +the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought +in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start + +pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View +more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly +22 years, but groundwater levels still suffer from years of drought. Image of the Day Land +Water As a persistent drought drags on, water levels are dropping at a key reservoir that +supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists + +could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence +Remote Sensing For more than 100 years, groups in the western United States have fought over +water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for +their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away +from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late + +1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. +Today, farmers are fighting fishermen, environmentalists, and Native American tribes over +the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and +operated by the U.S. Geological Survey, documented an extreme drought in the area along the +California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember + +10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember +10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer +and early fall of 2023. In September, low water levels limited barge shipments downriver and +threatened drinking water supplies in some Louisiana communities, according to the Associated +Press.Water levels were especially low near Memphis, Tennessee. The images above show the + +Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 +(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This +is the second year in a row drought has caused the river to fall to near-record lows at many +gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close +to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That + +was the lowest level recorded there since the start of National Weather Service records in +1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they +are measured with respect to a chosen reference point. That is why some gauge height measurements +are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near +the minimum operating level—since early September 2023. Water levels on the Mississippi normally + +decline in the fall and winter, and in 2022, the river did not get that low until mid-October. +September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in +2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. +In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according +to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department + +of Agriculture, the National Oceanic and Atmospheric Administration, and the University of +Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts +drought intensity in progressive shades of orange to red. It is based on an analysis of climate, +soil, and water condition measurements from more than 350 federal, state, and local observers +around the country. NASA contributes measurements and models that aid the drought monitoring + +effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. +Lack of precipitation and high temperatures over several months severely dried out soils in +states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of +soils in Louisiana were dry (short or very short on water) as of September 24. And for most +states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions + +along the river interrupted normal shipments of goods. According to the Associated Press, +barge companies reduced the weight carried in many shipments in September because the river +was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported +down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward +has risen 77 percent above the three-year average. The lack of freshwater flowing into the + +Gulf of Mexico has also allowed saltwater to make its way up the river and into some water +treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines +Parish are under drinking water advisories and have relied on bottled water for cooking and +drinking since June.Significant rainfall would be needed to flush out saltwater in the river +in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast + +Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late +October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren +Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States +Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area +in EO ExplorerIn September, low water levels made it more challenging to ship goods down the + +river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 +Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect +water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily +passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged +drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests + +in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record +keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low +water levels are making it difficult to ship goods down the river and allowing a wedge of +saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September +25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced + +algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae +once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long +lake has a watershed that spans one million square kilometers (386,000 square miles), draining +some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, +comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September + +25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around +this time, satellite observations analyzed by Environment and Climate Change Canada indicated +that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of +the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms +that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients + +like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain +blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm +the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that +can irritate the skin and cause liver and kidney damage.While algae are part of a natural +freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents + +and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches +in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer +months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels +were elevated in August, and visitors were advised to avoid swimming and fishing if green +scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between + +1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, +both in terms of occurrence and extent. The major contributors to the influx of phosphorous +to the lake were increased agricultural activities in the watershed and a higher frequency +of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost +three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 + +study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument +on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a +measure of phytoplankton biomass, were on average more than twice as high in the south basin, +compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from +the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx + +of nutrients in recent decades has contributed to the proliferation of algae in the large +Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View +more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are +sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can +become harmful to marine animals and humans.Cyanobacteria covered over half of the surface + +of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color +Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the +Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount +St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water +Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water + +Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October +3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall +within the dry season in the western and northern Amazon rainforest, but a particularly acute +lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI +(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched + +Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. +On that date, the level of the river, the largest tributary of the Amazon River, had dropped +to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, +the image on the left shows the same area on October 8, 2022, when the water level was 19.59 +meters, a more typical level for October. Rio Negro water levels continued to drop in the + +days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some +areas in the Amazon River’s watershed have received less rain between July and September than +any year since 1980, Reuters reported. The drought has been particularly severe in the Rio +Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern +Colombia.“Overall, this is a pretty unusual and extreme situation,” said RenĂ© Garreaud, an + +atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought +appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific +functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation +patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions +over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro + +and other nearby rivers have disrupted drinking water supplies in hundreds of communities, +slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and +largest city of the Brazilian state of Amazonas, is the primary transportation hub for the +upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other +industries with a presence in the city of two million people include chemical, ship, and electrical + +equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data +from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water +level of the largest tributary of the Amazon River has hit a record low.Image of the Day for +October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact +of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in + +the basin is dramatically evident in this pair of images, which show that every body of water +has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water +in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent +demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these +false-color images compare conditions along the Souris River, which reached a historic crest + +at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, +these false-color images show the Mississippi River near Natchez, Mississippi. The image from +May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember +6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter +rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried + +out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline +lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a +vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat +9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image +from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when + +water filled most of the basin and salt deposits were only visible around the perimeter of +the lake. The replenishment followed a period of above-average precipitation that sent a surge +of freshwater into the basin, expanding its watery footprint. Drier conditions have since +brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, +Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped + +more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, +agricultural water use, and dam construction on rivers feeding the lake have contributed to +the decline. A shrinking Lake Urmia has implications for ecological and human health. The +lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as +a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds + +for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover +for migratory species. However, with low lake levels, what water remains becomes more saline +and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking +lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds +and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with + +respiratory health impacts among the local population.The relative effects of climate, water +usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery +during a 10-year restoration program beginning in 2013. However, the efficacy of that effort +has been difficult to parse since strong rains also fell during that period. Some research +has concluded that climatic factors were primarily responsible for the recovery. NASA Earth + +Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. +Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of +water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, +2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest +since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and + +fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day +Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the +1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic +inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September +30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high + +levels, fueled by decades of human-caused climate warming and a recent boost from the natural +climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw +particularly high temperatures, with implications for the health of coral reefs.Corals thrive +within a small range of temperatures and become stressed when water is too hot or cold. Bleaching +occurs when stressed corals expel the algae that live inside them, stripping corals of their + +color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. +Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 +caused widespread bleaching.Stress on corals can also be detected using data from satellites. +This animation shows the evolution of accumulated heat stress from July through September +2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate + +of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s +Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA +Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations +have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching +can result. At values of 8, coral bleaching and widespread mortality are likely. By midway + +through this animation, in August, heat stress across much of the region already soared well +above both of those thresholds. According to NOAA, cumulative heat stress by late September +2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching +was already observed in some areas as early as July. Notice that areas of coral reef (gray) +near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative + +heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only +temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. +Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level +2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA +Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from + +Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn +Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large +accumulations of heat stress beginning in summer 2023, with implications for the health of +coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes +View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, + +with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of +the Day Life Water Image of the Day Heat Life Water Studying corals from above could help +scientists understand how these critical ecosystems will weather a changing climate. Image +of the Day Land Life Water Thank you for visiting nature.com. You are using a browser version +with limited support for CSS. To obtain the best experience, we recommend you use a more up + +to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to +ensure continued support, we are displaying the site without styles and JavaScript.Advertisement +Scientific Data volume 7, Article number: 112 (2020) Cite this article 30k Accesses126 Citations88 +AltmetricMetrics detailsRemotely sensed biomass carbon density maps are widely used for myriad +scientific and policy applications, but all remain limited in scope. They often only represent + +a single vegetation type and rarely account for carbon stocks in belowground biomass. To date, +no global product integrates these disparate estimates into an all-encompassing map at a scale +appropriate for many modelling or decision-making applications. We developed an approach for +harmonizing vegetation-specific maps of both above and belowground biomass into a single, +comprehensive representation of each. We overlaid input maps and allocated their estimates + +in proportion to the relative spatial extent of each vegetation type using ancillary maps +of percent tree cover and landcover, and a rule-based decision schema. The resulting maps +consistently and seamlessly report biomass carbon density estimates across a wide range of +vegetation types in 2010 with quantified uncertainty. They do so for the globe at an unprecedented +300-meter spatial resolution and can be used to more holistically account for diverse vegetation + +carbon stocks in global analyses and greenhouse gas inventories.Measurement(s)biomass carbon +densityTechnology Type(s)digital curationFactor Type(s)climatic zone ‱ above or below ground +‱ land coverSample Characteristic - Environmentorganic materialSample Characteristic - LocationEarth +(planet)Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.11872383Terrestrial +ecosystems store vast quantities of carbon (C) in aboveground and belowground biomass1. At + +any point in time, these stocks represent a dynamic balance between the C gains of growth +and C losses from death, decay and combustion. Maps of biomass are routinely used for benchmarking +biophysical models2,3,4, estimating C cycle effects of disturbance5,6,7, and assessing biogeographical +patterns and ecosystem services8,9,10,11. They are also critical for assessing climate change +drivers, impacts, and solutions, and factor prominently in policies like Reducing Emissions + +from Deforestation and Forest Degradation (REDD+) and C offset schemes12,13,14. Numerous methods +have been used to map biomass C stocks but their derivatives often remain limited in either +scope or extent12,15. There thus remains a critical need for a globally harmonized, integrative +map that comprehensively reports biomass C across a wide range of vegetation types.Most existing +maps of aboveground biomass (AGB) and the carbon it contains (AGBC) are produced from statistical + +or data-driven methods relating field-measured or field-estimated biomass densities and spaceborne +optical and/or radar imagery12,15,16. They largely focus on the AGB of trees, particularly +those in tropical landscapes where forests store the majority of the region’s biotic C in +aboveground plant matter. Land cover maps are often used to isolate forests from other landcover +types where the predictive model may not be appropriate such that forest AGB maps intentionally + +omit AGB stocks in non-forest vegetation like shrublands, grasslands, and croplands, as well +as the AGB of trees located within the mapped extent of these excluded landcovers17. Non-forest +AGB has also been mapped to some extent using similar approaches but these maps are also routinely +masked to the geographic extent of their focal landcover18,19,20,21. To date, there has been +no rigorous attempt to harmonize and integrate these landcover-specific, remotely sensed products + +into a single comprehensive and temporally consistent map of C in all living biomass.Maps +of belowground biomass (BGB) and carbon density (BGBC) are far less common than those of AGB +because BGB cannot be readily observed from space or airborne sensors. Consequently, BGB is +often inferred from taxa-, region-, and/or climate-specific “root-to-shoot” ratios that relate +the quantity of BGB to that of AGB22,23,24. These ratios can be used to map BGB by spatially + +applying them to AGB estimates using maps of their respective strata5. In recent years, more +sophisticated regression-based methods have been developed to predict root-to-shoot ratios +of some landcover types based on covariance with other biophysical and/or ecological factors25,26. +When applied spatially, these methods can allow for more continuous estimates of local BGB5,27. +Like AGBC, though, few attempts have been made to comprehensively map BGBC for the globe.Despite + +the myriad of emerging mapping methods and products, to date, the Intergovernmental Panel +on Climate Change (IPCC) Tier-1 maps by Ruesch and Gibbs28 remains the primary source of global +AGBC and BGBC estimates that transcend individual landcover types. These maps, which represents +the year 2000, were produced prior to the relatively recent explosion of satellite-based AGB +maps and they therefore rely on an alternative mapping technique called “stratify and multiply”15, + +which assigns landcover-specific biomass estimates or “defaults” (often derived from field +measurements or literature reviews) to the corresponding classified grid cells of a chosen +landcover map12. While this approach yields a comprehensive wall-to-wall product, it can fail +to capture finer-scale spatial patterns often evident in the field and in many satellite-based +products12,15. The accuracy of these maps is also tightly coupled to the quality and availability + +of field measurements29 and the thematic accuracy and discontinuity of the chosen landcover +map.Given the wealth of landcover-specific satellite based AGB maps, a new harmonization method +akin to “stratify and multiply” is needed to merge the validated spatial detail of landcover-specific +remotely sensed biomass maps into a single, globally harmonized product. We developed such +an approach by which we (i) overlay distinct satellite-based biomass maps and (ii) proportionately + +allocate their estimates to each grid cell (“overlay and allocate”). Specifically, we overlay +continental-to-global scale remotely sensed maps of landcover-specific biomass C density and +then allocate fractional contributions of each to a given grid cell using additional maps +of percent tree cover, thematic landcover and a rule-based decision tree. We implement the +new approach here using temporally consistent maps of AGBC as well as matching derived maps + +of BGBC to generate separate harmonized maps of AGBC and BGBC densities. In addition, we generate +associated uncertainty layers by propagating the prediction error of each input dataset. The +resulting global maps consistently represent biomass C and associated uncertainty across a +broad range of vegetation in the year 2010 at an unprecedented 300 meter (m) spatial resolution.Our +harmonization approach (Fig. 1) relies on independent, landcover-specific biomass maps and + +ancillary layers, which we compiled from the published literature (Table 1). When published +maps did not represent our epoch of interest (i.e. grasslands and croplands) or did not completely +cover the necessary spatial extent (i.e. tundra vegetation), we used the predictive model +reported with the respective map to generate an updated version that met our spatial and temporal +requirements. We then used landcover specific root-to-shoot relationships to generate matching + +BGBC maps for each of the input AGBC maps before implementing the harmonization procedure. +Below we describe, in detail, the methodologies used for mapping AGBC and BGBC of each landcover +type and the procedure used to integrate them.Generalized, three-step workflow used to create +harmonized global biomass maps. In step one, woody AGB maps are prepared, combined, converted +to AGBC density and used to create separate but complementary maps of BGBC. In step two, a + +similar workflow is used to generate matching maps of AGBC and BGBC for tundra vegetation, +grasses, and annual crops. In step three, all maps are combined using a rule-based decision +tree detailed in Fig. 3 to generate comprehensive, harmonized global maps. All input data +sources are listed and described in Table 1.Since the first remotely sensed woody AGB maps +were published in the early 1990s, the number of available products has grown at an extraordinary + +pace16 and it can thus be challenging to determine which product is best suited for a given +application. For our purposes, we relied on the GlobBiomass AGB density map30 as our primary +source of woody AGB estimates due to its precision, timestamp, spatial resolution, and error +quantification. It was produced using a combination of spaceborne optical and synthetic aperture +radar (SAR) imagery and represents the year 2010 at a 100 m spatial resolution – making it + +the most contemporary global woody AGB currently available and the only such map available +for that year. Moreover, GlobBiomass aims to minimize prediction uncertainty to less than +30% and a recent study suggests that it has high fidelity for fine-scale applications31.The +GlobBiomass product was produced by first mapping the growing stock volume (GSV; i.e. stem +volume) of living trees, defined following Food and Agriculture Organization (FAO) guidelines32 + +as those having a diameter at breast height (DBH) greater than 10 centimeters (cm). AGB density +was then determined from GSV by applying spatialized biomass expansion factors (BEFs) and +wood density estimates. These factors were mapped using machine learning methods trained from +a suite of plant morphological databases that compile thousands of field measurements from +around the globe33. The resulting AGB estimates represent biomass in the living structures + +(stems, branches, bark, twigs) of trees with a DBH greater than 10 cm. This definition may +thereby overlook AGB of smaller trees and/or shrubs common to many global regions. Unlike +other maps, though, the GlobBiomass product employs a subpixel masking procedure that retains +AGB estimates in 100 m grid cells in which any amount of tree cover was detected in finer +resolution (30 m) imagery34. This unique procedure retains AGB estimates in tree-sparse regions + +like savannahs, grasslands, croplands, and agroforestry systems where AGB is often overlooked17, +as well as in forest plantations. The GlobBiomass product is the only global map that also +includes a dedicated uncertainty layer reporting the standard error of prediction. We used +this layer to propagate uncertainty when converting AGB to AGBC density, modelling BGBC, and +integrating with C density estimates of other vegetation types.Bouvet et al.35 – some of whom + +were also participants of the GlobBiomass project – independently produced a separate AGB +density map for African savannahs, shrublands and dry woodlands circa 2010 at 25 m spatial +resolution35 (hereafter “Bouvet map”), which we included in our harmonized product to begin +to address the GlobBiomass map’s potential omission of small trees and shrubs that do not +meet the FAO definition of woody AGB. This continental map of Africa is based on a predictive + +model that directly relates spaceborne L-band SAR imagery – an indirect measure of vegetation +structure that is sensitive to low biomass densities36 – with region-specific, field-measured +AGB. Field measurements (n = 144 sites) were compiled from 7 different sampling campaigns +– each specifically seeking training data for biomass remote sensing – that encompassed 8 +different countries35. The resulting map is not constrained by the FAO tree definition and + +is masked to exclude grid cells in which predicted AGB exceeds 85 megagrams dry mater per +hectare (Mg ha−1) – the threshold at which the SAR-biomass relationship saturates. To avoid +extraneous prediction, it further excludes areas identified as “broadleaved evergreen closed-to-open +forest”, “flooded forests”, “urban areas” and “water bodies” by the European Space Agency’s +Climate Change Initiative (CCI) Landcover 2010 map37 and as “bare areas” in the Global Land + +Cover (GLC) 2000 map38. While the Bouvet map is not natively accompanied by an uncertainty +layer, its authors provided us with an analytic expression of its uncertainty (SE; standard +error of prediction) as a function of estimated AGB (Eq. 1) which we used to generate an uncertainty +layer for subsequent error propagation.We combined the GlobBiomass and Bouvet products to +generate a single woody biomass map by first upscaling each map separately to a matching 300 + +m spatial resolution using an area-weighted average to aggregate grid cells, and then assigning +the Bouvet estimate to all overlapping grid cells, except those identified by the CCI Landcover +2010 map as closed or flooded forest types (Online-only Table 1) which were not within the +dryland domain of the Bouvet map. While more complex harmonization procedures based on various +averaging techniques have been used by others39,40, their fidelity remains unclear since they + +fail to explicitly identify and reconcile the underlying source of the inputs’ discrepancies41. +We thus opted to use a more transparent ruled-based approach when combining these two woody +biomass maps, which allows users to easily identify the source of a grid cell’s woody biomass +estimate. Given the local specificity of the training data used to produce the Bouvet map, +we chose to prioritize its predictions over those of the GlobBiomass product when within its + +domain. In areas of overlap, the Bouvet map values tend to be lower in moist regions and higher +in dryer regions (Fig. 2), though, where used, these differences rarely exceed ±25 megagrams +C per hectare (MgC ha−1).Difference between underlying woody aboveground biomass maps in Africa. +Maps considered are the GlobBiomass30 global map and the Bouvet35 map of Africa. Both maps +were aggregated to a 300 m spatial resolution and converted to C density prior to comparison + +using the same schema. The difference map was subsequently aggregated to a 3 km spatial resolution +and reprojected for visualization. Negative values denote lower estimates by Bouvet et al.35, +while positive values denote higher estimates.We then converted all woody AGB estimates to +AGBC by mapping climate and phylogeny-specific biomass C concentrations from Martin et al.42. +Climate zones were delineated by aggregating classes of the Köppen-Gieger classification43 + +(Table 2) to match those of Martin et al.42. Phylogenetic classes (angiosperm, gymnosperm +and mixed/ambiguous) were subsequently delineated within each of these zones using aggregated +classes of the CCI Landcover 2010 map (Online-only Table 1). Martin et al.42 only report values +for angiosperms and gymnosperms so grid cells with a mixed or ambiguous phylogeny were assigned +the average of the angiosperm and gymnosperm values and the standard error of this value was + +calculated from their pooled variance. Due to residual classification error in the aggregated +phylogenetic classes, we weighted the phylogeny-specific C concentration within each climate +zone by the binary probability of correctly mapping that phylogeny (i.e. user’s accuracy)44 +using Eq. 2where, within each climate zone, ÎŒc is the mean probability-weighted C concentration +of the most probable phylogeny, ÎŒm is the mean C concentration of that phylogeny from Martin + +et al.42, pm is the user’s accuracy of that phylogeny’s classification (Table 3), and ÎŒn and +ÎŒo are the mean C concentrations of the remain phylogenetic classes from Martin et al.42. +Standard error estimates for these C concentrations were similarly weighted using summation +in quadrature (Eq. 3)where \({\sigma }_{c}\) is the probability-weighted standard error of +the most probable phylogeny’s C concentration and \({\sigma }_{m}\), \({\sigma }_{n}\) and + +\({\sigma }_{o}\) are the standard errors of the respective phylogeny-specific C concentrations +from Martin et al.42. Probability-weighted C concentrations used are reported in Table 4.Mapped, +probability-weighted C estimates were then arithmetically applied to AGB estimates. Uncertainty +associated with this correction was propagated using summation in quadrature of the general +form (Eq. 4)where \({\mu }_{f}=f(i,j,\ldots ,k)\), \({\sigma }_{f}\) is the uncertainty of + +ÎŒf, and \({\sigma }_{i},{\sigma }_{j},\ldots ,{\sigma }_{k}\), are the respective uncertainty +estimates of the dependent parameters (standard error unless otherwise noted). Here, ÎŒf, is +the estimated AGBC of a given grid cell, and is the product of its woody AGB estimate, and +its corresponding C concentration.The tundra and portions of the boreal biome are characterized +by sparse trees and dwarf woody shrubs as well as herbaceous cover that are not included in + +the GlobBiomass definition of biomass. AGB density of these classes has been collectively +mapped by Berner et al.18,45 for the North Slope of Alaska from annual Landsat imagery composites +of the normalized difference vegetation index (NDVI) and a non-linear regression-based model +trained from field measurements of peak AGB that were collected from the published literature +(n = 28 sites). Berner et al.18 note that while these field measurements did not constitute + +a random or systematic sample, they did encompass a broad range of tundra plant communities. +In the absence of a global map and due the sparsity of high quality Landsat imagery at high +latitudes, we extended this model to the pan-Arctic and circumboreal regions using NDVI composites +created from daily 250 m MODIS Aqua and Terra surface reflectance images46,47 that were cloud +masked and numerically calibrated to Landsat ETM reflectance – upon which the tundra model + +is based – using globally derived conversion coefficients48. We generated six separate 80th +percentile NDVI composites circa 2010 – one for each of the MODIS missions (Aqua and Terra) +in 2009, 2010 and 2011 – following Berner et al.18. We chose to use three years of imagery +(circa 2010) rather than just one (2010) to account for the potential influence that cloud +masking may exert upon estimates of the 80th NDVI percentile in a single year. We then applied + +the tundra AGB model to each composite, converted AGB estimates to AGBC by assuming a biomass +C fraction of 49.2% (SE = 0.8%)42 and generated error layers for each composite from the reported +errors of the AGB regression coefficients and the biomass C conversion factor using summation +in quadrature as generally described above (Eq. 4). A single composite of tundra AGBC circa +2010 was then created as the pixelwise mean of all six composites. We also generated a complementary + +uncertainty layer representing the cumulative standard error of prediction, calculated as +the pixelwise root mean of the squared error images in accordance with summation in quadrature. +Both maps were upscaled from their native 250 m spatial resolution to a 300 m spatial resolution +using an area weighted aggregation procedure, whereby pixels of the 300 m biomass layer was +calculated as the area weighted average of contained 250 m grid cells, and the uncertainty + +layer was calculated – using summation in quadrature – as the root area-weighted average of +the contained grid cells squared.Grassland AGBC density was modelled directly from maximum +annual NDVI composites using a non-linear regression-based model developed by Xia et al.19 +for mapping at the global scale. This model was trained by relating maximum annual NDVI as +measured by the spaceborne Advanced Very High-Resolution Radiometer (AVHRR) sensor to globally + +distributed field measurements of grassland AGBC that were compiled from the published literature +(81 sites for a total of 158 site-years). Like the tundra biomass training data, these samples +did not constitute a random or systematic sample but do encompass a comprehensive range of +global grassland communities. Given the inevitable co-occurrence of trees in the AVHRR sensor’s +8 km resolution pixels upon which the model is trained, it’s predictions of grassland AGBC + +are relatively insensitive to the effects of co-occurring tree cover. We thereby assume that +its predictions for grid cells containing partial tree cover represent the expected herbaceous +AGBC density in the absence of those trees. Maximum model predicted AGBC (NDVI = 1) is 2.3 +MgC ha−1 which is comparable to the upper quartile of herbaceous AGBC estimates from global +grasslands49 and suggests that our assumption will not lead to an exaggerated estimation. + +For partially wooded grid cells, we used modelled grassland AGBC density to represent that +associated with the herbaceous fraction of the grid cell in a manner similar to Zomer et al.17 +as described below (See “Harmonizing Biomass Carbon Maps”).We applied the grassland AGBC model +to all grid cells of maximum annual NDVI composites produced from finer resolution 16-day +(250 m) MODIS NDVI imagery composites circa 201050,51. Here again, three years of imagery + +were used to account for potential idiosyncrasies in a single year’s NDVI composites resulting +from annual data availability and quality. As with AGB of tundra vegetation, annual composites +(2009–2011) were constructed separately from cloud-masked imagery collected by both MODIS +missions (Aqua and Terra; n = 6) and then numerically calibrated to AVHRR reflectance using +globally derived conversion coefficients specific to areas of herbaceous cover52. We then + +applied the AGBC model to each of these composites and estimated error for each composite +from both the AVHRR calibration (standard deviation approximated from the 95% confidence interval +of the calibration scalar) and the AGBC model (relative RMSE) using summation in quadrature. +A single map of grassland AGBC circa 2010 was then created as the pixelwise mean of all six +composites and an associated error layer was created as the pixelwise root mean of the squared + +error images. Both maps were aggregated from their original 250 m resolution to 300 m to facilitate +harmonization using the area-weighted procedure described previously for woody and tundra +vegetation (see section 1.2).Prior to harvest, cropland biomass can also represent a sizable +terrestrial C stock. In annually harvested cropping systems, the maximum standing biomass +of these crops can be inferred from annual net primary productivity (ANPP). While spaceborne + +ANPP products exist, they generally perform poorly in croplands53,54. Instead, cropland ANPP +is more commonly derived from crop yields20,21,53. We used globally gridded, crop-specific +yields of 70 annually harvested herbaceous commodity crops circa 2000 by Monfreda et al.20 +– the only year in which these data were available. These maps were produced by spatially +disaggregating crop-yield statistics for thousands of globally distributed administrative + +units throughout the full extent of a satellite-based cropland map20. These maps were combined +with crop-specific parameters (Online-only Table 2) to globally map AGBC as aboveground ANPP +for each crop following the method of Wolf et al.21. This method can be simplified as (Eq. +5)where y is the crop’s yield (Mg ha−1), ω is the dry matter fraction of its harvested biomass, +h is its harvest index (fraction of total AGB collected at harvest) and c is the carbon content + +fraction of its harvested dry mass. This simplification assumes, following Wolf et al.21, +that 2.5% of all harvested biomass is lost between the field and farmgate and that unharvested +residue and root mass is 44% C.Total cropland AGBC density was then calculated as the harvested-area-weighted +average of all crop-specific AGBC estimates within a given grid cell. Since multiple harvests +in a single year can confound inference of maximum AGBC from ANPP, we further determined the + +harvest frequency (f) of each grid cell by dividing a cell’s total harvested area (sum of +the harvested area of each crop reported within a given grid cell) by its absolute cropland +extent as reported in a complementary map by Ramankutty et al.55. If f was greater than one, +multiple harvests were assumed to have occurred and AGBC was divided by f to ensure that AGBC +estimates did not exceed the maximum standing biomass density.Since the yields of many crops + +and, by association, their biomass have changed considerably since 200056,57, we calibrated +our circa 2000 AGBC estimates to the year 2010 using local rates of annual ANPP change (MgC +ha−1 yr−1) derived as the Theil-Sen slope estimator – a non-parametric estimator that is relatively +insensitive to outliers – of the full MODIS Terra ANPP timeseries (2000–2015)58. Total ANPP +change between 2000 and 2010 for each grid cell was calculated as ten times this annual rate + +of change. Since MODIS ANPP represents C gains in both AGB and BGB, we proportionately allocated +aboveground ANPP to AGBC using the total root-to-shoot ratio derived from the circa 2000 total +crop AGBC and BGBC maps (described below). Since error estimates were not available for the +yield maps or the crop-specific parameters used to generate the circa 2000 AGBC map, estimated +error of the circa 2010 crop AGBC map was exclusively based on that of the 2000–2010 correction. + +The error of this correction was calculated as the pixel-wise standard deviation of bootstrapped +simulations (n = 1000) in which a random subset of years was omitted from the slope estimator +in each iteration. The 8 km resolution circa 2000 AGBC map and error layer were resampled +to 1 km to match the resolution of MODIS ANPP using the bilinear method prior to ANPP correction +and then further resampled to 300 m to facilitate harmonization.Woody crops like fruit, nut, + +and palm oil plantations were not captured using the procedure just described and their biomass +was instead assumed to be captured by the previously described woody biomass products which +retained biomass estimates in all pixels where any amount of tree cover was detected at the +sub-pixel level (see section 1.1).Matching maps of BGBC and associated uncertainty were subsequently +produced for each of the landcover-specific AGBC maps using published empirical relationships.With + +the exception of savannah and shrubland areas, woody BGBC was modelled from AGBC using a multiple +regression model by Reich et al.25 that considers the phylogeny, mean annual temperature (MAT), +and regenerative origin of each wooded grid cell and that was applied spatially using maps +of each covariate in a fashion similar to other studies5,27. Tree phylogeny (angiosperm or +gymnosperm) was determined from aggregated classes of the CCI Landcover 2010 map37 (Online-only + +Table 1) with phylogenetically mixed or ambiguous classes assumed to be composed of 50% of +each. MAT was taken from version 2 of the WorldClim bioclimatic variables dataset (1970–2000) +at 1 km resolution59 and resampled to 300 m using the bilinear method. Since there is not +a single global data product mapping forest management, we determined tree origin – whether +naturally propagated or planted – by combining multiple data sources. These data included + +(i) a global map of “Intact Forest Landscapes” (IFL) in the year 201360 (a conservative proxy +of primary, naturally regenerating forests defined as large contiguous areas with minimal +human impact), (ii) a Spatial Database of Planted Trees (SDPT) with partial global coverage61, +(iii) national statistics reported by the FAO Global Forest Resources Assessment (FRA) on +the extent of both naturally regenerating and planted forests and woodlands within each country + +in the year 201062, and (iv) national statistics reported by the FAOSTAT database (http://www.fao.org/faostat) +on the planted area of plantation crops in 2010. Within each country, we assumed that the +total area of natural and planted trees was equal to the corresponding FRA estimates. If the +FAOSTAT-reported area of tree crops exceeded FRA-reported planted area, the difference was +added to FRA planted total. All areas mapped as IFL were assumed to be of natural origin and + +BGB was modelled as such. Likewise, besides the exceptions noted below, all tree plantations +mapped by the SDPT were assumed to be of planted origin. In countries where the extent of +the IFL or SDPT maps fell short of the FRA/FAOSTAT reported areas of natural or planted forests, +respectively, we estimated BGBC in the remaining, unknown-origin forest grid cells of that +country (BGBCu), as the probability-weighted average of the planted and natural origin estimates + +using Eq. 6where \(BGB{C}_{p}\) and \(BGB{C}_{n}\) are the respective BGBC estimates for a +grid cell assuming entirely planted and natural origin, respectively, and \({\Delta }_{p}\) +and \({\Delta }_{n}\) are the respective differences between (i) the FRA/FAOSTAT and (ii) +mapped extent of planted and natural forest within the given grid cell’s country. While the +mapped extent of IFL forests within a given country never exceeded that country’s FRA reported + +natural forest extent, there were infrequent cases (n = 22 of 257) in which the mapped extent +of tree plantations exceeded the corresponding FRA/FAOSTAT estimate of planted forest area. +In these cases, we down-weighted the BGB estimates of SDPT forests in a similar fashion such +that the weight of their planted estimate (\({\omega }_{p}\)) was equal to the quotient of +(i) the FRA/FAOSTAT planted area and (ii) the SDPT extent within the country, and the weight + +of the natural origin estimate applied to the SDPT extent (\({\omega }_{n}\)) was equal to +\(1-{\omega }_{p}\).A BGBC error layer was then produced using summation in quadrature from +the standard error estimates of the model coefficients, the AGBC error layer, the relative +RMSE of MAT (27%), and the derived global uncertainty of the phylogeny layer. Phylogeny error +was calculated as the Bernoulli standard deviation (ÎŽ) of the binary probability (p) of correct + +classification (i.e. “area weighted user’s accuracy”44; Table 3) using Eq. 7.Since savannahs +and shrublands are underrepresented in the regression-based model25, their BGBC was instead +estimated using static root-to-shoot ratios reported by Mokany et al.22, which are somewhat +conservative in comparison to the IPCC Tier-1 defaults23,24 put favoured for consistency with +methods used for grasslands (see below). Error was subsequently mapped from that of the AGBC + +estimates and the root-to-shoot ratios applied (Table 5).BGBC of tundra vegetation was mapped +from AGBC using a univariate regression model derived by Wang et al.26 that predicts root-to-shoot +ratio as a function of MAT. We applied the model using the WorldClim version 2 MAT map59 and +propagated error from the AGBC estimates, the relative RMSE of MAT and the standard error +of regression coefficients. Where tundra AGB exceeded 25 Mg ha−1 – the maximum field-measured + +shrub biomass reported by Berner et al.18 – vegetation was considered to include trees and +the Reich et al.25 method described earlier for woody vegetation was used instead.In the absence +of a continuous predictor of grassland root-to-shoot ratios, we applied climate specific root-to-shoot +ratios from Mokany et al.22 to the corresponding climate regions of the Köppen-Gieger classification43 +(Table 2). Here, again, these ratios vary slightly from the IPCC Tier-1 defaults23,24 but + +were chosen for their greater sample size and specificity. Grassland BGBC error was mapped +from the error of the AGBC estimates and the respective root-to-shoot ratios.Cropland BGBC +was again estimated from crop-specific yields and morphological parameters (Online-only Table +2) following Wolf et al.21 and Eq. 8where y is the crop’s yield (Mg ha−1), r is the root-to-shoot +ratio of the crop, and h is its harvest index. Here again we assume that 2.5% of all harvested + +biomass is lost between the field and farmgate and that root biomass is 44% C, following Wolf +et al.21. BGBC error was mapped from the error of the 2000-to-2010 ANPP correction for BGBC +allocation as described above for cropland AGBC.The AGBC and BGBC maps were harmonized separately +following the same general schema (Fig. 3). Given that our harmonized woody biomass map contains +biomass estimates for grid cells in which any amount of tree cover was detected at the subpixel + +level (see section 1.1), we conserved its estimates regardless of the landcover reported by +the 2010 CCI map in order to more fully account for woody biomass in non-forested areas17. +We then used the MODIS continuous vegetation fields percent tree cover map for 201063 to allocate +additional biomass density associated with the most probable herbaceous cover (grass or crop) +to each grid cell in quantities complementary to that of the grid cell’s fractional tree cover + +estimate (Eq. 9)where ÎŒT is the total biomass estimate of a grid cell, ÎŒw is the woody biomass +estimate for the grid cell, ÎŒh is its herbaceous biomass estimate, and q is the MODIS fractional +tree cover of the grid cell. Since MODIS tree cover estimates saturate at around 80%64, we +linearly stretched values such that 80% was treated as complete tree cover (100%). Moreover, +we acknowledge that percent cover can realistically exceed 100% when understory cover is considered + +but we were unable to reasonably determine the extent of underlying cover from satellite imagery. +As such, our approach may underestimate the contribution of herbaceous C stocks in densely +forested grid cells. The most likely herbaceous cover type was determined from the CCI Landcover +2010 map, which we aggregated into two “likely herbaceous cover” classes – grass or crop – +based on the assumed likelihood of cropland in each CCI class (Online-only Table 1). However, + +due to inherent classification error in the native CCI Landcover map, when determining the +herbaceous biomass contribution we weighted the relative allocation of crop and grass biomass +to a given grid cell based on the probability of correct classification by the CCI map (i.e. +“user’s accuracy”, Table 6) of the most probable herbaceous class (\({p}_{i}\)) such that +ÎŒh can be further expressed as (Eq. 10)where ÎŒi is the predicted biomass of the most probable + +herbaceous class, and ÎŒj is that of the less probable class.Decision tree used to allocate +landcover-specific biomass estimates to each grid cell of our harmonized global products.The +uncertainty of a grid cell’s total AGBC or BGBC estimate (\({\sigma }_{T}\)) was determined +and mapped from that of its components (\({\mu }_{w}\,{\rm{and}}\,{\mu }_{h}\)) by summation +in quadrature which can be simplified as (Eq. 11)where \({\sigma }_{w}\) is the error of the + +grid cell’s estimated ÎŒw, \({\sigma }_{h}\) is the error of its estimated ÎŒh, and \({\sigma +}_{q}\) is the error of its q. Here, \({\sigma }_{h}\) can be further decomposed and expressed +as Eq. 12 to account for the accuracy weighted allocation procedure expressed previously (Eq. +10)where \({\sigma }_{i}\) is the error of the estimated biomass density of the most probable +herbaceous class, \({\delta }_{i}\) is the estimated standard deviation of that class’s Bernoulli + +probability (p; Eq. 7), and \({\sigma }_{j}\) is the error of the estimated biomass density +of the less probable herbaceous subclass.Exceptions to the above schema were made in the tundra +and boreal biomes – as delineated by the RESOLVE Ecoregions 2017 biome polygons65 – where +thematic overlap was likely between the woody and tundra plant biomass maps. A separate set +of decision rules (Fig. 3) was used to determine whether grid cells in these biomes were to + +be exclusively allocated the estimate of the tundra plant map or that of the fractional allocation +procedure described above. In general, any land in these biomes identified as sparse landcover +by the CCI landcover map (Online-only Table 1) was assigned the tundra vegetation estimate. +In addition, lands north of 60° latitude with less than 10% tree cover or where the tundra +AGBC estimate exceeded that of the woody AGBC estimate were also exclusively assigned the + +tundra vegetation estimate. Lands north of 60° latitude not meeting these criteria were assigned +the woody value with the additional contribution of grass.Subtle numerical artefacts emerged +from the divergent methodologies employed north and south of 60°N latitude. These were eliminated +by distance weighting grid cells within 1° of 60°N based on their linear proximity to 60°N +and then averaging estimates such that values at or north of 61°N were exclusively based on + +the northern methodology, those at 60°N were the arithmetic average of the two methodologies +and those at or south of 59°N were exclusively based on the southern methodology. This produced +a seamless, globally harmonized product that integrates the best remotely sensed estimates +of landcover-specific C density. Water bodies identified as class “210” of the CCI 2010 landcover +map were then masked from our final products.Data layers (n = 4, Table 7) for the maps of + +AGBC and BGBC density (Fig. 4) as well as their associated uncertainty maps which represent +the combined standard error of prediction (Fig. 5) are available as individual 16-bit integer +rasters in GeoTiff format. All layers are natively in a WGS84 Mercator projection with a spatial +resolution of approximately 300 m at the equator and match that of the ESA CCI Landcover Maps37. +Raster values are in units megagrams C per hectare (MgC ha−1) and have been scaled by a factor + +of ten to reduce file size. These data are accessible through the Oak Ridge National Laboratory +(ORNL) DAAC data repository (https://doi.org/10.3334/ORNLDAAC/1763)66. In addition, updated +and/or derived vegetation-specific layers that were used to create our harmonized 2010 maps +are available as supplemental data on figshare67.Globally harmonized maps of above and belowground +living biomass carbon densities. (a) Aboveground biomass carbon density (AGBC) and (b) belowground + +biomass carbon density (BGBC) are shown separately. Maps have been aggregated to a 5 km spatial +resolution and reprojected here for visualization.Uncertainty of grid cell level above and +belowground biomass carbon density estimates. Uncertainty is shown here as the coefficient +of variation (%; standard error layer divided by mean estimate layer) of estimated AGBC (a) +and BGBC (b) densities after harmonization. Maps have been aggregated to a 5 km spatial resolution + +and projected for visualization.Our harmonized products rely almost exclusively upon maps +and models that have been rigorously validated by their original producers and were often +accompanied by constrained uncertainty estimates. Throughout our harmonization procedure, +we strived to conserve the validity of each of these products by minimizing the introduction +of additional error and by tracking any introductions, as described above, such that the final + +error layers represent the cumulative uncertainty of the inputs used. Ground truth AGB and +BGB data are almost always collected for individual landcover types. Consequently, we are +unable to directly assess the validity of our integrated estimates beyond their relationships +to individual landcover-specific estimates and the extents to which they were modified from +their original, previously-validated form prior to and during our harmonization procedure.Temporal + +and spatial updates made to existing landcover-specific maps of non-tree AGB resulted in relatively +small changes to their predictions. For example, we used numerically calibrated MODIS imagery +to extend the Landsat-based tundra plant AGB model beyond its native extent (the North Slope +of Alaska) to the pan-Arctic region since neither a comparable model nor a consistent Landsat +time series were available for this extent. We assessed the effects of these assumptions by + +comparing our predictions for the North Slope with those of the original map18 (Fig. 6a). +Both positive and negative discrepancies exist between ours and the original, though these +rarely exceed ±2 MgC ha−1 and no discernibly systematic bias was evident.Differences between +landcover-specific AGBC estimates from the original published maps and the modified versions +used as inputs to create the 2010 harmonized global maps. Tundra vegetation AGBC (a) is compared + +to the Landsat-based map of Berner et al.45 for the north slope of Alaska after converting +it to units MgC ha−1. Here, the comparison map was subsequently aggregated to a 1 km resolution +and reprojected for visualization. Grassland AGBC (b) is compared to the AVHRR-based map of +Xia et al.19 which represents the average estimate between 1982–2006. For visualization, the +map was aggregated to a 5 km resolution and subsequently reprojected after being masked to + +MODIS IGBP grasslands in the year 200685 following Xia et al.19. As such, this map does not +necessarily represent the spatial distribution of grid cells in which grassland estimates +were used. Cropland AGBC (c) is compared to the original circa 2000 estimates to assess the +effects of the 2000-to-2010 correction. The map is masked to the native extent of the combined +yield maps and aggregated to a 5 km resolution for visualization. For all maps, negative values + +indicate that our circa 2010 estimates are lower than those of the earlier maps while positive +values indicate higher estimates.Our updated map of grassland biomass carbon in the year 2010 +was similarly made by applying the original AVHRR-based model to calibrated MODIS imagery. +This too resulted in only subtle changes to the original biomass map (Fig. 6b) that were rarely +in excess of 0.5 MgC ha−1. In most areas, our estimates were higher than those of Xia et al.19 + +who mapped the mean AGBC density between 1986 and 2006. Most of these elevated estimates corresponded +with areas in which significant NDVI increases (“greening”) have been reported while notably +lower estimates in the Argentine Monte and Patagonian steppe biomes of southern South America, +likewise, correspond with areas of reported “browning”68,69. Both greening and browning trends +are well documented phenomena and have been linked to climatic changes70. Moreover, we further + +compared AGBC estimates from both the original Xia et al.19 map and our 2010 update to AGBC +field measurements coordinated by the Nutrient Network that were collected from 48 sites around +the world between 2007 and 200949. The RMSE (0.68 MgC ha−1) of our updated map was 10% less +that of the Xia et al. map for sites with less than 40% tree cover. Likewise, our 2010 estimates +were virtually unbiased (bias = −0.01 MgC ha−1) in comparison to the Xia map (bias = 0.25 + +MgC ha−1). While still noisy, these results suggest that our temporal update improved the +overall accuracy of estimated grassland AGBC.Finally, cropland biomass carbon maps were also +updated from their native epoch (2000) to 2010 using pixel-wise rates of MODIS ANPP change +over a ten-year period. While MODIS ANPP may be a poor snapshot of crop biomass in a single +year, we assumed that its relative change over time reflects real physiological shifts affecting + +the cropland C cycle. This correction also resulted in only small differences that rarely +exceeded ±2 MgC ha−1 and that, spatially, correspond well with observed declines in the yields +of select crops that have been linked to climate change71,72 (Fig. 6c). Nonetheless, updated +global yield maps comparable to those available for 2000 would greatly improve our understanding +of the interactions between climate change, crop yields, and C dynamics.Belowground biomass + +is notoriously difficult to measure, model, and also to validate. We accounted for the reported +uncertainty of nearly every variable considered when estimating belowground biomass and pixel-level +uncertainty, but we were unable to perform an independent validation of our harmonized estimates +at the pixel level due to a paucity of globally consistent field data. To complete such a +task, a globally orchestrated effort to collect more BGB samples data across all vegetation + +types is needed.Given this lack of data, we instead compared the estimated uncertainty of +our BGBC maps to that of our AGBC estimates to infer the sources of any divergence (Fig. 5). +As expected, our cumulative BGBC uncertainty layer generally reveals greater overall uncertainty +than our AGBC estimates, with BGBC uncertainty roughly twice that of AGBC throughout most +of the globe. The highest absolute uncertainty was found in biomass rich forests. Arid woodlands, + +especially those of the Sahel and eastern Namibia, generally had the greatest relative BGBC +uncertainty, though their absolute uncertainty was quite small (generally less than 3 MgC +ha−1). Here, biomass estimates of sparse woody vegetation were primarily responsible for heightened +relative uncertainty. High relative and absolute BGBC uncertainty were also associated with +predictions in select mountainous forests (e.g. east central Chile) as well as forested areas + +in and around cities. These patterns were largely driven by AGB uncertainty in the GlobBiomass +product.The GlobBiomass global woody AGB map produced by Santoro et al.30 comprises the backbone +of our integrated products and, with few exceptions, remains largely unchanged in our final +AGBC map. The native version of the GlobBiomass map is accompanied by an error layer describing +the uncertainty of each pixel’s biomass estimate and this too forms the core of our integrated + +uncertainty layers. In areas with tree cover, the global average error of GlobBiomass estimates +is 39 Mg ha−1 or 50% with greater relative uncertainty in densely forested areas, along the +margins of forested expanses like farm fields and cities, and in similar areas with sparse +tree cover.Adding additional grass or crop biomass in complementary proportion to a grid cell’s +tree cover often did not exceed the estimated error of the original GlobBiomass map (Fig. + +7). Grid cells exceeding GlobBiomass’s native uncertainty comprise less than 40% of its total +extent. Exceptions were primarily found in grassland and cropland dominated regions where +tree cover was generally sparse, and, consequently, the herbaceous biomass contribution was +relatively high. Even so, the absolute magnitude of these additions remains somewhat small +(less than 2.3 MgC ha−1 for grassland and 15 MgC ha−1 for cropland).Differences between the + +final harmonized AGBC map and GlobBiomass AGBC. GlobBiomass AGB was aggregated to a 300 m +spatial resolution and converted to C density prior to comparison. Negative values indicate +areas where the new map reports lower values than GlobBiomass while positive value denote +higher estimates.Larger deviations from GlobBiomass were also present in areas of both dryland +Africa and the Arctic tundra biome, where we used independent layers to estimate woody biomass. + +In African drylands, GlobBiomass likely underestimates woody biomass by adopting the conservative +FAO definition (DBH > 10 cm), which implicitly omits the relatively small trees and shrubs +that are common to the region. The Bouvet map of Africa that we used to supplement these estimates +is not bound by this constraint, was developed from region-specific data, and predicts substantially +higher AGB density throughout much of its extent with comparatively high accuracy (RMSE = + +17.1 Mg ha−1)35.GlobBiomass also included sporadic biomass estimates throughout much of the +Arctic tundra biome. Trees are generally scarce throughout this biome, which is instead dominated +by dwarf shrubs and herbaceous forbs and graminoids, so given GlobBiomass’s adherence to FAO +guidelines, its predictions here may be spurious. We thus prioritized the estimates of the +independent model developed specifically to collectively predict biomass of both woody and + +herbaceous tundra vegetation. These estimates were generally higher than GlobBiomass but agreed +well with independent validation data from North America (RMSE = 2.9 Mg ha−1)18.While far +from a perfect comparison, the only other map to comprehensively report global biomass carbon +density for all landcover types is the IPCC Tier-1 map for the year 2000 by Ruesch and Gibbs28. +As previously described, this map was produced using an entirely different method (“stratify + +and multiply”) and distinct data sources23 and represents an earlier epoch. However, the map +is widely used for myriad applications, and it may thus be informative to assess notable differences +between it and our new products.Ruesch and Gibbs28 report total living C stocks of 345 petagrams +(PgC) in AGBC and 133 PgC in BGBC for a total of 478 PgC, globally. Our estimates are lower +at 287 PgC and 122 PgC in global AGBC and BGBC, respectively, for a total of 409 PgC in living + +global vegetation biomass. Herbaceous biomass in our maps comprised 9.1 and 28.3 PgC of total +AGBC and BGBC, respectively. Half of all herbaceous AGBC (4.5 PgC) and roughly 6% of all herbaceous +BGBC (1.7 PgC) was found in croplands. Moreover, we mapped 22.3 and 6.1 PgC, respectively, +in the AGB and BGB of trees located within the cropland extent. These trees constituted roughly +7% of all global biomass C and are likely overlooked by both the Ruesch and Gibbs map28 and + +by remotely sensed forest C maps that are masked to forested areas. Zomer et al.17 first highlighted +this potential discrepancy in the Ruesch and Gibbs map28 when they produced a remarkably similar +estimate of 34.2 Pg of overlooked C in cropland trees using Tier-1 defaults. However, their +estimates were assumed to be in addition to the 474 PgC originally mapped by Ruesch and Gibbs28. +Here, we suggest that the 28.4 PgC we mapped in cropland trees is already factored into our + +409 PgC total.Our AGBC product predicts substantially less biomass C than Ruesch and Gibbs28 +throughout most of the pantropical region and, to a lesser extent, southern temperate forests +(Fig. 8a). This pattern has been noted by others comparing the Ruesch and Gibbs map28 to other +satellite-based biomass maps73 and may suggest that the IPCC default values used to create +it23 are spatially biased. In addition, well-defined areas of high disagreement emerge in + +Africa that directly correspond with the FAO boundaries of the “tropical moist deciduous forest” +ecofloristic zone and suggest that this area, in particular, may merit critical review. Moreover, +the opposite pattern is observed in this same ecofloristic zone throughout South America. +Our map also predicts greater AGBC throughout much of the boreal forest as well as in African +shrublands and the steppes of South America.Differences between the 2010 harmonized global + +maps of above and belowground biomass carbon density and those of the IPCC Tier-1 product +by Ruesch and Gibbs for 2000. Comparisons of AGBC (a) and BGBC (b) maps are shown separately. +Negative values indicate that the circa 2010 estimates are comparatively lower while positive +values indicate higher estimates.We observed similar, though less pronounced discrepancies, +when comparing BGBC maps (Fig. 8b). Notably, our map predicts substantially more BGBC throughout + +the tundra biome – a previously underappreciated C stock that has recently risen to prominance74 +– the boreal forest, African shrublands and most of South America and Australia. However, +we predict less BGBC in nearly all rainforests (Temperate and Tropical). These differences +and their distinct spatial patterns correspond with the vegetation strata used to make the +IPCC Tier-1 map28 and suggest that the accuracy of the “stratify and multiply” method depends + +heavily upon the quality of the referenced and spatial data considered. Inaccuracies in these +data may, in turn, lead to false geographies. Integrating, continuous spatial estimates that +better capture local and regional variation, as we have done, may thus greatly improve our +understanding of global carbon geographies and their role in the earth system.The error and +variance between our woody biomass estimates – when aggregated to the country level – and + +comparable totals reported in the FRA were less for comparisons made against FRA estimates +generated using higher tier IPCC methodologies than for those based on Tier-1 approaches (Fig. +9). Across the board for AGBC, BGBC, and total C comparisons, the relative RMSE (RMSECV) of +our estimates, when compared to estimates generated using high tier methods, was roughly half +of that obtained from comparisons with Tier-1 estimates (Table 8). Likewise, the coefficient + +of determination (R2) was greatest for comparisons with Tier-3 estimates. For each pool-specific +comparison (AGBC, BGBC, and total C), the slopes of the relationships between Tier-1, 2, and +3 estimates were neither significantly different from a 1:1 relationship nor from one another +(p > 0.05; ANCOVA). Combined, these results suggest that our maps lead to C stock estimates +congruent with those attained from independent, higher-tier reporting methodologies.Comparison + +of woody biomass density estimates to corresponding estimates of the FAO’s FRA and the USFS’s +FIA. National woody AGBC totals derived from the woody components of our harmonized maps are +compared to national totals reported in the 2015 FRA62 (a) in relation to the IPCC inventory +methodology used by each country. Likewise, we derived woody AGBC totals for US states and +compared them to the corresponding totals reported by the 2014 FIA75 (b), a Tier-3 inventory. + +We also show the additional effect of considering non-woody C – as is reported in our harmonized +maps – in light green. Similar comparisons were made between our woody BGBC estimates and +the corresponding estimates of both the FRA (c) and FIA (d). We further summed our woody AGBC +and BGBC estimates and compared them to the total woody C stocks reported by both the FRA +(e) and FIA (f).To explore this association at a finer regional scale, we also compared our + +woody C estimates to the United States Forest Service’s Forest Inventory Analysis75 (FIA) +and found similarly strong congruence for AGBC and Total C stocks but subtle overestimates +for BGBC (Fig. 9). The FIA is a Tier-3 inventory of woody forest biomass C stocks that is +based on extensive and statistically rigorous field sampling and subsequent upscaling, We +used data available at the state level for the year 2014 – again, the only year in which we + +could obtain data partitioned by AGBC and BGBC. Like our FRA comparison, we found a tight +relationship between our woody AGBC totals and those reported by the FIA (Fig. 9b; RMSECV += 25.7%, R2 = 0.960, slope = 1.10, n = 48). Our woody BGBC estimates, though, were systematically +greater than those reported by the FIA (Fig. 9d; RMSECV = 86.4%, R2 = 0.95, slope = 1.51, +n = 48). This trend has been noted by others27 and suggests that the global model that we + +used to estimate woody BGBC may not be appropriate for some finer scale applications as is +foretold by the elevated uncertainty reported in our corresponding uncertainty layer (Fig. +5b). Our total woody C (AGBC + BGBC) estimates (Fig. 9f), however, agreed well with the FIA +(RMSECV = 34.1%, R2 = 0.961, slope = 1.17, n = 48) and thus reflect the outsized contribution +of AGBC to the total woody C stock. When the contribution of herbaceous C stocks is further + +added to these comparisons, our stock estimates intuitively increase in rough proportion to +a state’s proportional extent of herbaceous cover. The effect of this addition is particularly +pronounced for BGBC estimates due to the large root-to-shoot ratios of grassland vegetation.The +relative congruence of our results with higher-tier stock estimates suggests that our maps +could be used to facilitate broader adoption of higher-tier methods among countries currently + +lacking the requisite data and those seeking to better account for C in non-woody biomass. +This congruence spans a comprehensive range of biophysical conditions and spatial scales ranging +from small states to large nations. Moreover, a recent study suggests that the fidelity of +the underlying GlobBiomass AGB map may extend to even finer scales31. While our BGBC estimates +may differ from some fine-scale estimates (Fig. 9d), their tight agreement with high tier + +BGBC totals at the national level (Fig. 9c) suggests that they may still be well suited for +many national-scale C inventories – especially for countries lacking requisite high tier data. +Use of our maps is unlikely to introduce error in excess of that currently implicit in Tier-1 +estimates. Credence, though, should be given to the associated uncertainty estimates. To facilitate +wider adoption of higher-tier methodologies, our maps could be used to derive new, region-specific + +default values for use in Tier-2 frameworks76 or to either represent or calibrate 2010 baseline +conditions in Tier-3 frameworks. In so doing, inventories and studies alike could more accurately +account for the nuanced global geographies of biomass C.These maps are intended for global +applications in which continuous spatial estimates of live AGBC and/or BGBC density are needed +that span a broad range of vegetation types and/or require estimates circa 2010. They are + +loosely based upon and share the spatial resolution of the ESA CCI Landcover 2010 map37, which +can be used to extract landcover specific C totals. However, our products notably do not account +for C stored in non-living C pools like litter or coarse woody debris, nor soil organic matter, +though these both represent large, additional ecosystem C stocks77,78,79. Our maps are explicitly +intended for global scale applications seeking to consider C in the collective living biomass + +of multiple vegetation types. For global scale applications focused exclusively on the C stocks +of a single vegetation type, we strongly encourage users to instead use the respective input +map or model referenced in Table 1 to avoid potential errors that may have been introduced +by our harmonization procedure. For AGB applications over smaller extents, users should further +consider whether locally specific products are available. If such maps are not available and + +our maps are considered instead, credence should be given to their pixel-level uncertainty +estimates. As mentioned above, the biomass of shrublands was only explicitly accounted for +in Africa and the Arctic tundra, since neither broad-scale maps nor models generalizable to +other areas were available in the existing literature. As such, we caution against the use +of our maps outside of these areas when shrubland biomass is of particular interest or importance. + +Moreover, in contrast to the estimates for all other vegetation types considered, which we +upscaled to a 300 m resolution, cropland C estimates were largely based on relatively coarse +8 km resolution data that were downscaled using bilinear resampling to achieve a 300 m spatial +resolution. As such, these estimates may not adequately capture the underlying finer-scale +spatial variation and should be interpreted with that in mind. Likewise, we reiterate that + +some BGBC estimates may differ from locally derived Tier-3 estimates, and attention should +thus be given to our reported pixel-level uncertainty for all applications. Finally, our maps +should not be used in comparison with the IPCC Tier-1 map of Ruesch and Gibbs (2008) to detect +biomass change between the two study periods due to significant methodological differences +between these products.Cropland biomass maps were created in the R statistical computing environment80. + +All other coding was done in Google Earth Engine81 (GEE), wherein our workflow consisted of +18 interconnected scripts. All code can be found on GitHub (https://github.com/sethspawn/globalBiomassC) +and permanently archived by Zenodo82.Houghton, R. A., Hall, F. & Goetz, S. J. Importance of +biomass in the global carbon cycle. J. Geophys. Res. Biogeosciences 114 (2009).Huntzinger, +D. N. et al. The North American Carbon Program Multi-Scale Synthesis and Terrestrial Model + +Intercomparison Project – Part 1: Overview and experimental design. Geosci. Model Dev 6, 2121–2133 +(2013).Article ADS Google Scholar Schwalm, C. R. et al. Toward “optimal” integration of terrestrial +biosphere models. Geophys. Res. Lett. 42, 4418–4428 (2015).Article ADS Google Scholar Li, +W. et al. Land-use and land-cover change carbon emissions between 1901 and 2012 constrained +by biomass observations. Biogeosciences 14, 5053–5067 (2017).Article Google Scholar Spawn, + +S. A., Lark, T. J. & Gibbs, H. K. Carbon emissions from cropland expansion in the United States. +Environ. Res. Lett. 14, 045009 (2019).Article CAS ADS Google Scholar Harris, N. L. et al. +Baseline Map of Carbon Emissions from Deforestation in Tropical Regions. Science 336, 1573–1576 +(2012).Article CAS PubMed ADS Google Scholar Baccini, A. et al. Tropical forests are a net +carbon source based on aboveground measurements of gain and loss. Science 358, 230–234 (2017).Article + +MathSciNet CAS PubMed MATH ADS Google Scholar Strassburg, B. B. N. et al. Global congruence +of carbon storage and biodiversity in terrestrial ecosystems. Conserv. Lett 3, 98–105 (2010).Article +Google Scholar West, P. C. et al. Trading carbon for food: Global comparison of carbon stocks +vs. crop yields on agricultural land. Proc. Natl. Acad. Sci. 107, 19645–19648 (2010).Article +CAS PubMed ADS PubMed Central Google Scholar Carvalhais, N. et al. Global covariation of carbon + +turnover times with climate in terrestrial ecosystems. Nature 514, 213–217 (2014).Article +CAS PubMed ADS Google Scholar BrandĂŁo, A. et al. Estimating the Potential for Conservation +and Farming in the Amazon and Cerrado under Four Policy Scenarios. Sustainability 12, 1277 +(2020).Article Google Scholar Gibbs, H. K., Brown, S., Niles, J. O. & Foley, J. A. Monitoring +and estimating tropical forest carbon stocks: making REDD a reality. Environ. Res. Lett. 2, + +045023 (2007).Article ADS CAS Google Scholar Fargione, J. E. et al. Natural climate solutions +for the United States. Sci. Adv. 4, eaat1869 (2018).Article PubMed PubMed Central ADS Google +Scholar Griscom, B. W. et al. Natural climate solutions. Proc. Natl. Acad. Sci. 114, 11645–11650 +(2017).Article CAS PubMed ADS PubMed Central Google Scholar Goetz, S. J. et al. Mapping and +monitoring carbon stocks with satellite observations: a comparison of methods. Carbon Balance + +Manag 4, 2 (2009).Article PubMed PubMed Central CAS Google Scholar Xiao, J. et al. Remote +sensing of the terrestrial carbon cycle: A review of advances over 50 years. Remote Sens. +Environ. 233, 111383 (2019).Article ADS Google Scholar Zomer, R. J. et al. Global Tree Cover +and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national +carbon budgets. Sci. Rep 6, 29987 (2016).Article CAS PubMed PubMed Central ADS Google Scholar + +Berner, L. T., Jantz, P., Tape, K. D. & Goetz, S. J. Tundra plant above-ground biomass and +shrub dominance mapped across the North Slope of Alaska. Environ. Res. Lett. 13, 035002 (2018).Article +ADS Google Scholar Xia, J. et al. Spatio-Temporal Patterns and Climate Variables Controlling +of Biomass Carbon Stock of Global Grassland Ecosystems from 1982 to 2006. Remote Sens 6, 1783–1802 +(2014).Article ADS Google Scholar Monfreda, C., Ramankutty, N. & Foley, J. A. Farming the + +planet: 2. Geographic distribution of crop areas, yields, physiological types, and net primary +production in the year 2000. Glob. Biogeochem. Cycles 22, GB1022 (2008).Article ADS CAS Google +Scholar Wolf, J. et al. Biogenic carbon fluxes from global agricultural production and consumption. +Glob. Biogeochem. Cycles 29, 1617–1639 (2015).Article CAS ADS Google Scholar Mokany, K., Raison, +R. J. & Prokushkin, A. S. Critical analysis of root: shoot ratios in terrestrial biomes. Glob. + +Change Biol. 12, 84–96 (2006).Article ADS Google Scholar IPCC 2006. 2006 IPCC Guidelines for +National Greenhouse Gas Inventories. vol. 4 (IPCC National Greenhouse Gas Inventories Programme, +2006).IPCC 2019. 2019 Refinement to the 2006 IPCC Guidlines for National Greenhouse Gas Inventories. +vol. 4 (IPCC National Greenhouse Gas Inventories Programme, 2019).Reich, P. B. et al. Temperature +drives global patterns in forest biomass distribution in leaves, stems, and roots. Proc. Natl. + +Acad. Sci. 111, 13721–13726 (2014).Article CAS PubMed ADS PubMed Central Google Scholar Wang, +P. et al. Belowground plant biomass allocation in tundra ecosystems and its relationship with +temperature. Environ. Res. Lett. 11, 055003 (2016).Article ADS CAS Google Scholar Russell, +M. B., Domke, G. M., Woodall, C. W. & D’Amato, A. W. Comparisons of allometric and climate-derived +estimates of tree coarse root carbon stocks in forests of the United States. Carbon Balance + +Manag 10, 20 (2015).Article PubMed PubMed Central CAS Google Scholar Ruesch, A. & Gibbs, H. +New IPCC Tier-1 Global Biomass Carbon Map for the Year 2000. Carbon Dioxide Information Analysis +Center, Oak Ridge National Laboratory, http://cdiac.ess-dive.lbl.gov (2008).Schimel, D. et +al. Observing terrestrial ecosystems and the carbon cycle from space. Glob. Change Biol. 21, +1762–1776 (2015).Article ADS Google Scholar Santoro, M. et al. GlobBiomass - global datasets + +of forest biomass. PANGAEA https://doi.org/10.1594/PANGAEA.894711 (2018).Huang, W. et al. +High-Resolution Mapping of Aboveground Biomass for Forest Carbon Monitoring System in the +3 Tri-State Region of Maryland, Pennsylvania and Delaware, USA. Environ. Res. Lett. 14, 095002 +(2019).Article ADS Google Scholar Food and Agricultural Organization. FRA 2015 Terms and Definitions. +(Food and Agricultural Organization of the United Nations, 2012).Quegan, S. et al. DUE GlobBiomass: + +D6 - Global Biomass Map Algorithm Theoretical Basis Document. GlobBiomass, http://globbiomass.org/wp-content/uploads/DOC/Deliverables/D6_D7/GlobBiomass_D6_7_Global_ATBD_v2.pdf +(2017).Hansen, M. C. et al. High-Resolution Global Maps of 21st-Century Forest Cover Change. +Science 342, 850–853 (2013).Article CAS PubMed ADS Google Scholar Bouvet, A. et al. An above-ground +biomass map of African savannahs and woodlands at 25 m resolution derived from ALOS PALSAR. +Remote Sens. Environ. 206, 156–173 (2018).Article ADS Google Scholar Le Toan, T., Beaudoin, + +A., Riom, J. & Guyon, D. Relating forest biomass to SAR data. IEEE Trans. Geosci. Remote Sens +30, 403–411 (1992).Article ADS Google Scholar European Space Agency. 300 m Annual global land +cover time series from 1992 to 2015. European Space Agency - Climate Change Initiative, http://maps.elie.ucl.ac.be/CCI/viewer/download.php +(2017).BartholomĂ©, E. & Belward, A. S. GLC2000: a new approach to global land cover mapping +from Earth observation data. Int. J. Remote Sens. 26, 1959–1977 (2005).Article ADS Google + +Scholar Avitabile, V. et al. An integrated pan-tropical biomass map using multiple reference +datasets. Glob. Change Biol. 22, 1406–1420 (2016).Article ADS Google Scholar Englund, O. et +al. A new high-resolution nationwide aboveground carbon map for Brazil. Geo Geogr. Environ. +4, e00045 (2017).Article Google Scholar Scholze, M., Buchwitz, M., Dorigo, W., Guanter, L. +& Quegan, S. Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon + +cycle data assimilation systems. Biogeosciences 14, 3401–3429 (2017).Article CAS ADS Google +Scholar Martin, A. R., Doraisami, M. & Thomas, S. C. Global patterns in wood carbon concentration +across the world’s trees and forests. Nat. Geosci. 11, 915 (2018).Article CAS ADS Google Scholar +Kottek, M., Grieser, J., Beck, C., Rudolf, B. & Rubel, F. World Map of the Köppen-Geiger climate +classification updated. Meteorol. Z. 15, 259–263 (2006).Article Google Scholar Olofsson, P. + +et al. Good practices for estimating area and assessing accuracy of land change. Remote Sens. +Environ. 148, 42–57 (2014).Article ADS Google Scholar Berner, L. T., Jantz, P., Tape, K. D. +& Goetz, S. J. ABoVE: Gridded 30-m Aboveground Biomass, Shrub Dominance, North Slope, AK, +2007–2016. Oak Ridge National Laboratory Distributed Active Archive Center https://doi.org/10.3334/ORNLDAAC/1565 +(2018).Vermote, E. F. & Wolfe, R. MYD09GQ MODIS/Aqua Surface Reflectance Daily L2G Global + +250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MYD09GQ.006 +(2015).Vermote, E. F. & Wolfe, R. MOD09GQ MODIS/Terra Surface Reflectance Daily L2G Global +250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MOD09GQ.006 +(2015).Steven, M. D., Malthus, T. J., Baret, F., Xu, H. & Chopping, M. J. Intercalibration +of vegetation indices from different sensor systems. Remote Sens. Environ. 88, 412–422 (2003).Article + +ADS Google Scholar Adler, P. B. et al. Productivity Is a Poor Predictor of Plant Species Richness. +Science 333, 1750–1753 (2011).Article CAS PubMed ADS Google Scholar Didan, K. MYD13Q1 MODIS/Aqua +Vegetation Indices 16-Day L3 Global 250 m SIN Grid V006. NASA EOSDIS Land Processes Distributed +Active Archive Center, https://doi.org/10.5067/MODIS/MYD13Q1.006 (2015).Didan, K. MOD13Q1 +MODIS/Terra Vegetation Indices 16-Day L3 Global 250 m SIN Grid V006. NASA EOSDIS Land Processes + +Distributed Active Archive Center https://doi.org/10.5067/MODIS/MOD13Q1.006 (2015).Fensholt, +R. & Proud, S. R. Evaluation of Earth Observation based global long term vegetation trends +— Comparing GIMMS and MODIS global NDVI time series. Remote Sens. Environ. 119, 131–147 (2012).Article +ADS Google Scholar Li, Z. et al. Comparing cropland net primary production estimates from +inventory, a satellite-based model, and a process-based model in the Midwest of the United + +States. Ecol. Model. 277, 1–12 (2014).Article Google Scholar Turner, D. P. et al. Evaluation +of MODIS NPP and GPP products across multiple biomes. Remote Sens. Environ. 102, 282–292 (2006).Article +ADS Google Scholar Ramankutty, N., Evan, A. T., Monfreda, C. & Foley, J. A. Farming the planet: +1. Geographic distribution of global agricultural lands in the year 2000. Glob. Biogeochem. +Cycles 22, GB1003 (2008).Grassini, P., Eskridge, K. M. & Cassman, K. G. Distinguishing between + +yield advances and yield plateaus in historical crop production trends. Nat. Commun. 4, 2918 +(2013).Article PubMed ADS CAS Google Scholar Gray, J. M. et al. Direct human influence on +atmospheric CO2 seasonality from increased cropland productivity. Nature 515, 398–401 (2014).Article +CAS PubMed ADS Google Scholar Running, S. W., Mu, Q. & Zhao, M. MOD17A3H MODIS/Terra Net Primary +Production Yearly L4 Global 1 km SIN Grid V055. NASA EOSDIS Land Processes Distributed Active + +Archive Center, https://lpdaac.usgs.gov/products/mod17a3v055/ (2015).Fick, S. & Hijmans, R. +WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas. Int. J. Climatol. +37, 4302–4315 (2017).Article Google Scholar Potapov, P. et al. The last frontiers of wilderness: +Tracking loss of intact forest landscapes from 2000 to 2013. Sci. Adv. 3, e1600821 (2017).Article +PubMed PubMed Central ADS Google Scholar Harris, N. L., Goldman, E. D. & Gibbes, S. Spatial + +Database of Planted Trees (SDPT Version 1.0). World Resources Institute, https://www.wri.org/publication/planted-trees +(2019).Food and Agricultural Organization. Global Forest Resources Assessment 2015: Desk Reference. +(Food and Agricultural Organization of the United Nations, 2015).Dimiceli, C. et al. MOD44B +MODIS/Terra Vegetation Continuous Fields Yearly L3 Global 250 m SIN Grid V006. NASA EOSDIS +Land Processes Distributed Active Archive Center, https://doi.org/10.5067/MODIS/MOD44B.006 + +(2015).Sexton, J. O. et al. Global, 30-m resolution continuous fields of tree cover: Landsat-based +rescaling of MODIS vegetation continuous fields with lidar-based estimates of error. Int. +J. Digit. Earth 6, 427–448 (2013).Article ADS Google Scholar Dinerstein, E. et al. An Ecoregion-Based +Approach to Protecting Half the Terrestrial Realm. BioScience 67, 534–545 (2017).Article PubMed +PubMed Central Google Scholar Spawn, S. A. & Gibbs, H. K. Global Aboveground and Belowground + +Biomass Carbon Density Maps for the Year 2010. Oak Ridge National Laboratory Distributed Active +Archive Center, https://doi.org/10.3334/ORNLDAAC/1763 (2019).Spawn, S. A., Sullivan, C. C., +Lark, T. J. & Gibbs, H. K. Harmonized global maps of above and belowground biomass carbon +density in the year 2010. figshare https://doi.org/10.6084/m9.figshare.c.4561940 (2020).Gao, +Q. et al. Climatic change controls productivity variation in global grasslands. Sci. Rep 6, + +26958 (2016).Article CAS PubMed PubMed Central ADS Google Scholar de Jong, R., Verbesselt, +J., Schaepman, M. E. & de Bruin, S. Trend changes in global greening and browning: contribution +of short-term trends to longer-term change. Glob. Change Biol 18, 642–655 (2012).Article ADS +Google Scholar Gonsamo, A., Chen, J. M. & Lombardozzi, D. Global vegetation productivity response +to climatic oscillations during the satellite era. Glob. Change Biol. 22, 3414–3426 (2016).Article + +ADS Google Scholar Ray, D. K. et al. Climate change has likely already affected global food +production. Plos One 14, e0217148 (2019).Article CAS PubMed PubMed Central Google Scholar +Lobell, D. B., Schlenker, W. & Costa-Roberts, J. Climate Trends and Global Crop Production +Since 1980. Science 333, 616–620 (2011).Article CAS PubMed ADS Google Scholar Hu, T. et al. +Mapping Global Forest Aboveground Biomass with Spaceborne LiDAR, Optical Imagery, and Forest + +Inventory Data. Remote Sens 8, 565 (2016).Article ADS Google Scholar Iversen, C. M. et al. +The unseen iceberg: plant roots in arctic tundra. New Phytol. 205, 34–58 (2015).Article PubMed +Google Scholar USDA Forest Service. Forest Inventory and Analysis National Program: Standard +Tables of Forest Caron Stock Estimates by State. Forest Inventory and Analysis National Program, +https://www.fia.fs.fed.us/forestcarbon/index.php (2014).Langner, A., Achard, F. & Grassi, + +G. Can recent pan-tropical biomass maps be used to derive alternative Tier 1 values for reporting +REDD + activities under UNFCCC? Environ. Res. Lett. 9, 124008 (2014).Article ADS Google Scholar +JobbĂĄgy, E. G. & Jackson, R. B. The Vertical Distribution of Soil Organic Carbon and Its Relation +to Climate and Vegetation. Ecol. Appl. 10, 423–436 (2000).Article Google Scholar Scharlemann, +J. P., Tanner, E. V., Hiederer, R. & Kapos, V. Global soil carbon: understanding and managing + +the largest terrestrial carbon pool. Carbon Manag 5, 81–91 (2014).Article CAS Google Scholar +Domke, G. M., Woodall, C. W., Walters, B. F. & Smith, J. E. From Models to Measurements: Comparing +Downed Dead Wood Carbon Stock Estimates in the U.S. Forest Inventory. Plos One 8, e59949 (2013).Article +CAS PubMed PubMed Central ADS Google Scholar R Core Team. R: A Language and Environment for +Statistical Computing, https://www.R-project.org/ (2017).Gorelick, N. et al. Google Earth + +Engine: Planetary-scale geospatial analysis for everyone. Remote Sens. Environ. 202, 18–27 +(2017).Article ADS Google Scholar Spawn, S. A. sethspawn/globalBiomassC. Zenodo https://doi.org/10.5281/zenodo.3647567 +(2020).Olson, D. M. et al. Terrestrial Ecoregions of the World: A New Map of Life on EarthA +new global map of terrestrial ecoregions provides an innovative tool for conserving biodiversity. +BioScience 51, 933–938 (2001).European Space Agency. Land Cover CCI Product User Guide Version + +2, D3.4-PUG, v2.5. European Space Agency - Climate Change Initiative, http://maps.elie.ucl.ac.be/CCI/viewer/download/ESACCI-LC-PUG-v2.5.pdf +(2016).Friedl, M. A. & Sulla-Menashe, D. MCD12Q1 MODIS/Terra + Aqua Land Cover Type Yearly +L3 Global 500 m SIN Grid V006. NASA EOSDIS Land Processes Distributed Active Archive Center, +https://doi.org/10.5067/MODIS/MCD12Q1.006 (2019).Jing, Q., BĂ©langer, G., Baron, V. & Bonesmo, +H. Modeling the Biomass and Harvest Index Dynamics of Timothy. Agron. J. 103, 1397–1404 (2011).Article + +Google Scholar West, T. O. et al. Cropland carbon fluxes in the United States: increasing +geospatial resolution of inventory-based carbon accounting. Ecol. Appl. 20, 1074–1086 (2010).Article +PubMed Google Scholar Unkovich, M., Baldock, J. & Forbes, M. Variability in harvest index +of grain crops and potential significance for carbon accounting: examples from Australian +agriculture. Adv. Agron 105, 173–219 (2010).Article Google Scholar Hay, R. K. M. Harvest index: + +a review of its use in plant breeding and crop physiology. Ann. Appl. Biol. 126, 197–216 (1995).Article +Google Scholar Larcher, W. Physiological Plant Ecology: Ecophysiology and Stress Physiology +of Functional Groups. (Springer-Verlag, 2003).Hakala, K., Keskitalo, M. & Eriksson, C. Nutrient +uptake and biomass accumulation for eleven different field crops. Agric. Food Sci 18, 366–387 +(2009).Article CAS Google Scholar Bolinder, M. A., Janzen, H. H., Gregorich, E. G., Angers, + +D. A. & VandenBygaart, A. J. An approach for estimating net primary productivity and annual +carbon inputs to soil for common agricultural crops in Canada. Agric. Ecosyst. Environ 118, +29–42 (2007).Article Google Scholar Mackenzie, B. A. & Van Fossen, L. Managing Dry Grain In +Storage. In Agricultural Engineers’ Digest vol. 20 (Purdue University Cooperative Extension +Service, 1995).Goodwin, M. Crop Profile for Dry Bean in Canada. Agriculture and Agri-Food + +Canada, http://publications.gc.ca/collections/collection_2009/agr/A118-10-4-2005E.pdf (2005).Schulte +auf’m Erley, G., Kaul, H.-P., Kruse, M. & Aufhammer, W. Yield and nitrogen utilization efficiency +of the pseudocereals amaranth, quinoa, and buckwheat under differing nitrogen fertilization. +Eur. J. Agron. 22, 95–100 (2005).Article CAS Google Scholar Bjorkman, T. Northeast Buckwheat +Growers Newsletter No. 19. Cornell University NYSAES, http://www.hort.cornell.edu/bjorkman/lab/buck/NL/june05.php + +(2005).Kyle, G. P. et al. GCAM 3.0 Agriculture and Land Use: Data Sources and Methods, https://doi.org/10.2172/1036082 +(2011).Bastin, S. & Henken, K. Water Content of Fruits and Vegetables. University of Kentucky +Cooperative Extension Service, https://www.academia.edu/5729963/Water_Content_of_Fruits_and_Vegetables +(1997).Smil, V. Crop Residues: Agriculture’s Largest HarvestCrop residues incorporate more +than half of the world’s agricultural phytomass. BioScience 49, 299–308 (1999).Article Google + +Scholar Squire, G. R. The physiology of tropical crop production. (C.A.B. International, 1990).Williams, +J. R. et al. EPIC users guide v. 0509. Texas A & M University Blackland Research and Extension +Center, http://epicapex.tamu.edu/files/2013/02/epic0509usermanualupdated.pdf (2006).Okeke, +J. E. Cassava varietal improvement for processing and utilization in livestock feeds. In Cassava +as Livestock Feed in Africa (International Institute of Tropical Agriculture, 1992).Pongsawatmanit, + +R., Thanasukarn, P. & Ikeda, S. Effect of Sucrose on RVA Viscosity Parameters, Water Activity +and Freezable Water Fraction of Cassava Starch Suspensions. ScienceAsia 28, 129–134 (2002).Article +CAS Google Scholar Gigou, J. et al. Fonio Millet (Digitaria Exilis) Response to N, P and K +Fertilizers Under Varying Climatic Conditions in West. AFRICA. Exp. Agric 45, 401–415 (2009).Article +Google Scholar Food and Agricultural Organization. FAOSTAT 2001: FAO statistical databasees. + +FAOSTAT, http://www.fao.org/faostat/en/#data (2006).Bolinder, M. A., Angers, D. A., BĂ©langer, +G., Michaud, R. & LaverdiĂšre, M. R. Root biomass and shoot to root ratios of perennial forage +crops in eastern Canada. Can. J. Plant Sci. 82, 731–737 (2002).Article Google Scholar Deferne, +J. & Pate, D. W. Hemp seed oil: A source of valuable essential fatty acids. J. Int. Hemp Assoc +3, 4–7 (1996). Google Scholar Islam, Md. R. et al. Study of Harvest Index and Genetic Variability + +in White Jute (Corchorus capsularis) Germplasm. J. Biol. Sci. 2, 358–360 (2002).Article Google +Scholar Ahad, A. & Debnath, C. N. Shoot Root Ratio of Jute Varieties and the Nature of Association +Between Root Characteristics and the Yield of Dry Matter and Fiber. Bangladesh J. Agric. Res +13, 17–22 (1988). Google Scholar Mondal, S. S., Ghosh, A. & Debabrata, A. Effect of seeding +time of linseed (Linum usitatissimum) in rice (Oryza sativa)-based paira cropping system under + +rainfed lowland condition. Indian J. Agric. Sci 75, 134–137 (2005). Google Scholar Ayaz, S., +Moot, D. J., Mckenzie, B. A., Hill, G. D. & Mcneil, D. L. The Use of a Principal Axis Model +to Examine Individual Plant Harvest Index in Four Grain Legumes. Ann. Bot. 94, 385–392 (2004).Article +CAS PubMed PubMed Central Google Scholar Goudriaan, J. & Van Laar, H. H. Development and growth. +In Modelling Potential Crop Growth Processes: Textbook with Exercises (eds. Goudriaan, J. + +& Van Laar, H. H.) 69–94 (Springer Netherlands, 1994).National Research Council. Nutrient +Requirements of Nonhuman Primates: Second Revised Edition. (The National Academies Press, +2003).Roth, C. M., Shroyer, J. P. & Paulsen, G. M. Allelopathy of Sorghum on Wheat under Several +Tillage Systems. Agron. J. 92, 855–860 (2000).Article Google Scholar Heidari Zooleh, H. et +al. Effect of alternate irrigation on root-divided Foxtail Millet (Setaria italica). Aust. + +J. Crop Sci 5, 205–2013 (2011). Google Scholar BrĂŒck, H., Sattelmacher, B. & Payne, W. A. +Varietal differences in shoot and rooting parameters of pearl millet on sandy soils in Niger. +Plant Soil 251, 175–185 (2003).Article Google Scholar Oelke, E. A., Putnam, D. H., Teynor, +T. M. & Oplinger, E. S. Quinoa. In Alternative Field Crops Manual (University of Wisconsin-Extension, +Cooperative Extension, 1992).Robertson, M. J., Silim, S., Chauhan, Y. S. & Ranganathan, R. + +Predicting growth and development of pigeonpea: biomass accumulation and partitioning. Field +Crops Res 70, 89–100 (2001).Article Google Scholar Armstrong, E. Desiccation & harvest of +field peas. In Pulse management in Southern New South Wales (State of New South Wales Agriculture, +1999).Fischer, R. A. (Tony) & Edmeades, G. O. Breeding and Cereal Yield Progress. Crop Sci. +50, S-85–S-98 (2010).Article Google Scholar Atlin, G. N. et al. Developing rice cultivars + +for high-fertility upland systems in the Asian tropics. Field Crops Res 97, 43–52 (2006).Article +Google Scholar Bueno, C. S. & Lafarge, T. Higher crop performance of rice hybrids than of +elite inbreds in the tropics: 1. Hybrids accumulate more biomass during each phenological +phase. Field Crops Res 112, 229–237 (2009).Article Google Scholar Yang, J. & Zhang, J. Crop +management techniques to enhance harvest index in rice. J. Exp. Bot 61, 3177–3189 (2010).Article + +CAS PubMed Google Scholar Ziska, L. H., Namuco, O., Moya, T. & Quilang, J. Growth and Yield +Response of Field-Grown Tropical Rice to Increasing Carbon Dioxide and Air Temperature. Agron. +J. 89, 45–53 (1997).Article Google Scholar Mwaja, V. N., Masiunas, J. B. & Weston, L. A. Effects +of fertility on biomass, phytotoxicity, and allelochemical content of cereal rye. J. Chem. +Ecol. 21, 81–96 (1995).Article CAS PubMed Google Scholar Bruinsma, J. & Schuurman, J. J. The + +effect of spraying with DNOC (4,6-dinitro-o-cresol) on the growth of the roots and shoots +of winter rye plants. Plant Soil 24, 309–316 (1966).Article CAS Google Scholar Yau, S. K., +Sidahmed, M. & Haidar, M. Conservation versus Conventional Tillage on Performance of Three +Different Crops. Agron. J. 102, 269–276 (2010).Article Google Scholar Hojati, M., Modarres-Sanavy, +S. A. M., Karimi, M. & Ghanati, F. Responses of growth and antioxidant systems in Carthamustinctorius + +L. under water deficit stress. Acta Physiol. Plant. 33, 105–112 (2011).Article Google Scholar +Oelke, E. A. et al. Safflower. In Alternative Field Crops Manual (University of Wisconsin-Extension, +Cooperative Extension, 1992).Perez, R. Chapter 3: Sugar cane. In Feeding pigs in the tropics +(Food and Agricultural Organization of the United Nations, 1997).Van Dillewijn, C. Botany +of Sugarcane. (Chronica Botanica Co, 1952).Pate, F. M., Alvarez, J., Phillips, J. D. & Eiland, + +B. R. Sugarcane as a Cattle Feed: Production and Utilization. (University of Florida Extension +Institute of Food and Agricultural Sciences, 2002).Download referencesWe gratefully acknowledge +all the data producers, without whom this work would not be possible. We especially thank +Maurizio Santoro et al., Alexandre Bouvet et al., Jiangzhou Xia et al., Logan T. Berner et +al., Chad Monfreda et al., and Julie Wolf et al. whose AGB estimates comprise the core of + +our harmonized products and, in many cases, whose feedback greatly improved the quality of +their inclusion. We are also grateful to the thoughtful feedback of three anonymous reviewers +whose suggestions greatly improved the quality of our products and the clarity of our manuscript. +Funding for this project was generously provided by the David and Lucile Packard Foundation +and the National Wildlife Federation.Department of Geography, University of Wisconsin-Madison, + +Madison, WI, USASeth A. Spawn, Clare C. Sullivan & Holly K. GibbsCenter for Sustainability +and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University +of Wisconsin-Madison, Madison, WI, USASeth A. Spawn, Clare C. Sullivan, Tyler J. Lark & Holly +K. GibbsYou can also search for this author in PubMed Google ScholarYou can also search for +this author in PubMed Google ScholarYou can also search for this author in PubMed Google ScholarYou + +can also search for this author in PubMed Google ScholarS.A.S. designed the harmonization +procedure, compiled and standardized individual biomass layers, conducted all mapping, and +led manuscript development. C.C.S., T.J.L. and H.K.G. assisted with conceptualization, and +manuscript development.Correspondence to Seth A. Spawn.The authors declare no competing interests.Publisher’s +note Springer Nature remains neutral with regard to jurisdictional claims in published maps + +and institutional affiliations.Open Access This article is licensed under a Creative Commons +Attribution 4.0 International License, which permits use, sharing, adaptation, distribution +and reproduction in any medium or format, as long as you give appropriate credit to the original +author(s) and the source, provide a link to the Creative Commons license, and indicate if +changes were made. The images or other third party material in this article are included in + +the article’s Creative Commons license, unless indicated otherwise in a credit line to the +material. If material is not included in the article’s Creative Commons license and your intended +use is not permitted by statutory regulation or exceeds the permitted use, you will need to +obtain permission directly from the copyright holder. To view a copy of this license, visit +http://creativecommons.org/licenses/by/4.0/.The Creative Commons Public Domain Dedication + +waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files associated +with this article.Reprints and PermissionsSpawn, S.A., Sullivan, C.C., Lark, T.J. et al. Harmonized +global maps of above and belowground biomass carbon density in the year 2010. Sci Data 7, +112 (2020). https://doi.org/10.1038/s41597-020-0444-4Download citationReceived: 03 July 2019Accepted: +14 February 2020Published: 06 April 2020DOI: https://doi.org/10.1038/s41597-020-0444-4Anyone + +you share the following link with will be able to read this content:Sorry, a shareable link +is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing +initiative Nature Water (2023)Nature Plants (2023)Nature Communications (2023)Scientific Data +(2023)Nature Communications (2023)Advertisement Scientific Data (Sci Data) ISSN 2052-4463 +(online) © 2023 Springer Nature LimitedSign up for the Nature Briefing newsletter — what matters + +in science, free to your inbox daily.Find and use NASA Earth science data fully, openly, and +without restrictions.Recognizing the connections between interdependent Earth systems is critical +for understanding the world in which we live.The atmosphere is a gaseous envelope surrounding +and protecting our planet from the intense radiation of the Sun and serves as a key interface +between the terrestrial and ocean cycles.The biosphere encompasses all life on Earth and extends + +from root systems to mountaintops and all depths of the ocean. It is critical for maintaining +species diversity, regulating climate, and providing numerous ecosystem functions.The cryosphere +encompasses the frozen parts of Earth, including glaciers and ice sheets, sea ice, and any +other frozen body of water. The cryosphere plays a critical role in regulating climate and +sea levels.The human dimensions discipline includes ways humans interact with the environment + +and how these interactions impact Earth’s systems. It also explores the vulnerability of human +communities to natural disasters and hazards.The land surface discipline includes research +into areas such as shrinking forests, warming land, and eroding soils. NASA data provide key +information on land surface parameters and the ecological state of our planet.This vast, critical +reservoir supports a diversity of life and helps regulate Earth’s climate.Processes occurring + +deep within Earth constantly are shaping landforms. Although originating from below the surface, +these processes can be analyzed from ground, air, or space-based measurements.The Sun influences +a variety of physical and chemical processes in Earth’s atmosphere. NASA continually monitors +solar radiation and its effect on the planet.The terrestrial hydrosphere includes water on +the land surface and underground in the form of lakes, rivers, and groundwater along with + +total water storage.Whether you are a scientist, an educator, a student, or are just interested +in learning more about NASA’s Earth science data and how to use them, we have the resources +to help. Get information and guides to help you find and use NASA Earth science data, services, +and tools.We provide a variety of ways for Earth scientists to collaborate with NASA.Making +NASA's free and open Earth science data interactive, interoperable, and accessible for research + +and societal benefit both today and tomorrow.Changes in the land surface can impact climate, +terrestrial ecosystems, and hydrology. Land surface-related data, including land cover type, +land surface temperature, and topography, are critical for monitoring agricultural practices +and water resource availability and for guiding interventions when necessary.Land surface +reflectance is a measure of the fraction of incoming solar radiation reflected from Earth's + +surface to a satellite-borne or aircraft-borne sensor. These data are useful because they +provide an estimate of the surface spectral reflectance as it would be measured at ground +level in the absence of atmospheric scattering or absorption, which is referred to as atmospheric +correction.Land surface reflectance data can be used for visualizing the surface as well as +for computing metrics and creating models that are useful for specific analysis. Agricultural + +production estimates must be restricted to crop-specific areas (e.g., corn, soybeans, etc.) +to avoid confusion with other crops, natural vegetation, and areas of no vegetation. This +allows specific crops to be observed over time using sustained land imaging and multi-spectral +high-resolution imagery.An asterisk (*) next to an entry indicating that near real-time (NRT) +data products are available through NASA's Land, Atmosphere Near real-time Capability for + +EOS (LANCE) within three hours from satellite observation. Imagery is generally available +3-5 hours after observation. While not intended for scientific research, NRT data are good +resources for monitoring ongoing or time-critical events.Sensor(s)/ Model NameObservation +or Model500 m, 1 km, 5,600 m2017-present15 m, 30 m, 60 mOLI/OLI-2: 9 bands ranging from 0.43 +”m to 1.38 ”mETM+: 8 bands ranging from 0.45 ”m to 12.5 ”mTM: 7 bands ranging in wavelength + +from 0.45 ”m to 2.35 ”mOLI-2, OLI, ETM+, TMGeoTIFFOLI/OLI-2: 9 bands ranging from 0.43 ”m +to 1.38 ”mMSI: 12 bands ranging from 0.443 ”m to 2.190 ”mThe Advanced Spaceborne Thermal Emission +and Reflection Radiometer (ASTER) instrument is a cooperative effort between NASA and Japan's +Ministry of Economy, Trade and Industry (METI). ASTER Surface Reflectance data can be visualized +and interactively explored using NASA Worldview:Research quality ASTER data products are available + +through Earthdata Search:Back to the TableThe Enhanced Thematic Mapper (ETM+), the Operational +Land Imager (OLI) and OLI-2, and the Thermal Infrared Sensor-2 (TIRS-2) are aboard the joint +NASA/USGS Landsat series of satellites.OLI data can be visualized and interactively explored +using NASA Worldview:Research quality Landsat land surface reflectance data products can be +accessed directly using USGS EarthExplorer:Back to the TableHarmonized Landsat Sentinel-2 + +(HLS) data provide consistent global observation of Earth’s surface reflectance and top-of-atmosphere +(TOA) brightness data from the Landsat OLI and OLI-2 and the ESA (European Space Agency) Multi-Spectral +Instrument (MSI) aboard the Sentinel-1A/B satellites every 2-3 days with 30 meter spatial +resolution.HLS Surface Reflectance data can be visualized and interactively explored using +NASA Worldview:Research quality HLS data products can be accessed directly from Earthdata + +Search:The Application for Extracting and Exploring Analysis Ready Samples (AppEEARS) tool +offers a simple and efficient way to access, transform, and visualize geospatial data from +a variety of federal data archives, including USGS Landsat Analysis Ready Data (ARD) surface +reflectance products. Back to the TableModerate Resolution Imaging Spectroradiometer (MODIS) +Surface Reflectance products provide an estimate of the surface spectral reflectance as it + +would be measured at ground level in the absence of atmospheric scattering or absorption.MODIS +Surface Reflectance data can be visualized and interactively explored using NASA Worldview:Multiple +Geographic Information Systems (GIS) MODIS Surface Reflectance data layers with different +band combinations are available through Esri’s ArcGIS OnLine (AGOL). NASA GIS data may be +used with open-source GIS software such as Quantum GIS or Geographic Resources Analysis Support + +System (GRASS). Learn more about these tools in the Use the Data section below.Research quality +MODIS data products can be accessed directly from Earthdata Search:Near real-time (NRT) MODIS +Surface Reflectance data are available through NASA’s Land, Atmosphere Near real-time Capability +for EOS (LANCE) within 60 to 125 minutes after a satellite observation:Back to the TableThe +Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is aboard the NASA/NOAA Suomi + +National Polar-orbiting Partnership (Suomi NPP) and NOAA-20 satellites. VIIRS/NPP Land Surface +Reflectance Data from Earthdata Search Data are available daily and 8-day at various spatial +resolutions.Near real-time (NRT) VIIRS Surface Reflectance data are available through LANCE +within 60 to 125 minutes after a satellite observation:Back to the TableLand Surface Temperature +(LST) describes processes such as the exchange of energy and water between the land surface + +and Earth's atmosphere. LST influences the rate and timing of plant growth and is affected +by the albedo, or reflectance, of a surface. These data can improve decision-making for water +use and irrigation strategies, and are also an indicator for crop health and water stress.An +asterisk (*) next to an entry indicating that near real-time (NRT) data products are available +through NASA's Land, Atmosphere Near real-time Capability for EOS (LANCE) within three hours + +from satellite observation. Imagery is generally available 3-5 hours after observation. While +not intended for scientific research, NRT data are good resources for monitoring ongoing or +time-critical events.1 km, 0.05°0.25°, 0.5°, 1° GeoTIFFMODIS LST data can be visualized and +interactively explored using NASA Worldview:MODIS LST data can be visualized in Giovanni:Research +quality LST data products can be accessed directly from Earthdata Search and also are available + +through the Data Pool at NASA’s Land Processes DAAC (LP DAAC).The AppEEARS tool and MODIS +subsetting tools can be used to quickly extract a subset of MODIS data for a region of interest.Near +real-time (NRT) MODIS LST data are available through LANCE within 60 to 125 minutes after +a satellite observation.Back to the TableResearch quality LST data from the Advanced Spaceborne +Thermal Emission and Reflection Radiometer (ASTER) are available in HDF-EOS format:Back to + +the TableA suite of MODIS LST and Emissivity (LST&E) products are available that combine MODIS +data with ASTER data to leverage the strengths from both sensors. These integrated LST data +can be visualized and interactively explored using NASA Worldview:Back to the TableThe ECOsystem +Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission measures the +temperature of plants to better understand how much water plants need and how they respond + +to stress.The AppEEARS tool and MODIS subsetting tools can be used to quickly extract a subset +of ECOSTRESS data for a region of interest.Back to the TableThe Visible Infrared Imaging Radiometer +Suite (VIIRS) instrument is aboard the NASA/NOAA Suomi National Polar-orbiting Partnership +(Suomi NPP) and NOAA-20 satellites. Research quality LST data products from VIIRS: Near real-time +(NRT) VIRS LST data are available through LANCE within 60 to 125 minutes after a satellite + +observation:Back to the TableLST data are produced as part of the NASA/USGS Landsat series +of Earth observing missions.