Community Earth System Model

Community Earth System Model
Name	Community Earth System Model
Developer	National Center for Atmospheric Research; U.S. Department of Energy; University Corporation for Atmospheric Research
Released	2010
Programming language	Fortran; C; Python
Operating system	Unix-like; Linux; macOS
License	Open-source

Contents

Community Earth System Model

The Community Earth System Model is a coupled climate system modeling framework used for simulating climate change, atmospheric circulation, ocean circulation, sea ice, land surface processes, biogeochemistry, and interactions among those components. Developed through collaborations among institutions such as the National Center for Atmospheric Research, the U.S. Department of Energy, and the University Corporation for Atmospheric Research, the model underpins multi-decadal simulations and contributes to international assessments like the Intergovernmental Panel on Climate Change reports. It supports research spanning paleoclimate experiments linked to the Last Glacial Maximum, near-term projections tied to Representative Concentration Pathways, and long-term projections relevant to the Paris Agreement.

Overview

The model integrates atmosphere, ocean, sea ice, and land components to represent Earth system processes that inform studies associated with Intergovernmental Panel on Climate Change, United Nations Framework Convention on Climate Change, World Meteorological Organization, International Geosphere-Biosphere Programme, and Global Carbon Project research agendas. Users from facilities such as the National Science Foundation, Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory, Los Alamos National Laboratory, Pacific Northwest National Laboratory, NOAA Geophysical Fluid Dynamics Laboratory, and NASA Goddard Institute for Space Studies employ the system for experiments aligned with scenarios like Shared Socioeconomic Pathways and Representative Concentration Pathways. The project connects to community codes and infrastructures like Earth System Modeling Framework, ESGF (Earth System Grid Federation), CIME (Component Interface Management) workflows, and high-performance computing centers including NERSC and NCAR Cheyenne.

Origins trace to legacy modeling efforts by NCAR Community Climate System Model teams, collaborations with Department of Energy laboratories, and university groups at Columbia University and Princeton University. Milestones include integrations of biogeochemical modules from programs like Carbon Cycle Data Assimilation System and paleoclimate components informed by studies of the Pleistocene Epoch and the Holocene. Major development phases corresponded with international assessments such as successive IPCC Assessment Reports and community transitions to model intercomparison projects including CMIP5 and CMIP6. Governance and funding have involved agencies such as the National Aeronautics and Space Administration, U.S. Environmental Protection Agency, European Centre for Medium-Range Weather Forecasts, and research consortia including International CLIVAR Project.

The architecture couples an atmospheric general circulation model to an ocean general circulation model, a sea ice model, and a land surface model, together with chemistry and biogeochemistry modules developed in partnerships with groups at Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Max Planck Institute for Meteorology, University of Oxford, and Columbia University's Lamont-Doherty Earth Observatory. Technical frameworks leverage software practices from Earth System Modeling Framework, component managers like CESM-CIME, and workflow tools used at Argonne National Laboratory and Lawrence Livermore National Laboratory. The codebase implements numerical methods, parameterizations, and fluid dynamics approaches informed by foundational work from Vilhelm Bjerknes-inspired dynamical frameworks and modern numerical schemes used by groups at Princeton University and MIT.

Researchers use the model to examine phenomena ranging from El Niño–Southern Oscillation to Atlantic Meridional Overturning Circulation, cryosphere dynamics connected to Greenland ice sheet and Antarctic ice sheet responses, and terrestrial carbon feedbacks tied to Amazon rainforest and Siberian permafrost dynamics. Policy-relevant analyses support mitigation and adaptation discussions relevant to the Paris Agreement, national assessments such as those by the U.S. Global Change Research Program, and sectoral studies for the World Bank and IPCC authors. The model contributes to cross-disciplinary studies linking to paleoclimate proxy syntheses from projects like the PAGES (Past Global Changes) initiative and modern observational programs run by NOAA, NASA, European Space Agency, and regional agencies including Met Office and Environment and Climate Change Canada.

Validation employs observational datasets from satellite missions such as TOPEX/Poseidon, Jason, MODIS, Aqua (satellite), and reanalysis products like ERA-Interim, ERA5, MERRA-2, and observational networks maintained by Global Ocean Observing System and Global Climate Observing System. Model intercomparison occurs through participation in CMIP5 and CMIP6, coordinated experiments overseen by the World Climate Research Programme and evaluated by research centers including NCAR, GFDL, IPSL, EC-Earth, Met Office Hadley Centre, Max Planck Institute for Meteorology, and CSIRO. Performance tuning and scalability are assessed on supercomputers such as Summit (supercomputer), Fugaku, Titan (supercomputer), and cluster systems at NERSC with profiling contributed by teams at Argonne National Laboratory and Oak Ridge National Laboratory.

The project operates as a community model with governance involving consortia including NCAR, the U.S. Department of Energy, and academic partners such as University of Washington, University of California, Los Angeles, Iowa State University, University of Colorado Boulder, University of Michigan, Yale University, Harvard University, Princeton University, and Stanford University. Development follows open-source practices with code management, issue tracking, and contribution workflows similar to those used by GitHub-hosted scientific projects and supported through training workshops at meetings like the American Geophysical Union Fall Meeting and European Geosciences Union General Assembly. Outreach and capacity building engage international partners including Indian Institute of Science, Chinese Academy of Sciences, Australian National University, University of Cape Town, and Brazilian National Institute for Space Research. The community coordinates model experiments through portals and archives linked to Earth System Grid Federation resources and stewardship by institutions such as NCAR and DOE laboratories.

Category:Climate models