The U.S. research centers that develop climate and Earth system models and the U.S. scientific community are key participants in long-running collaborative efforts to improve knowledge on climate change. A number of major interagency activities supporting improvements in climate modeling took place in 2019.

Most prominently, the World Climate Research Programme Coupled Model Intercomparison Project (CMIP) is currently in its sixth phase (CMIP6). The earlier phases of CMIP experiments have provided the research community with large, detailed model-generated datasets that allow them to evaluate and improve various aspects of model performance and develop projections of future climate change. CMIP6 is the largest such modeling experiment so far, with a number of intercomparison projects that examine specific Earth system components and processes, including aerosol chemistry, detection and attribution of climate change, and the evaluation of and potential risks related to geoengineering, among many others.

Model output from CMIP6 and prior CMIPs will continue to be analyzed, validated, and used by the research community to improve future predictive models, allowing scientists and practitioners to develop and deliver much higher resolution climate projections at a global scale, and to better understand how the climate system functions and how it can be simulated with greater accuracy. The outcomes of analyses of CMIP6 model output will inform the next Intergovernmental Panel on Climate Change assessment report and the Fifth National Climate Assessment. Many U.S. modeling centers are participating in the CMIP6 effort, including the National Center for Atmospheric Research (NCAR; primarily sponsored by NSF, with some additional support from NOAA, NASA, DOE, DoD, and the Federal Aviation Administration), DOE’s Energy Exascale Earth System Model effort, NOAA’s Geophysical Fluid Dynamics Laboratory, and NASA’s Goddard Institute for Space Studies.

CMIP6 datasets are already being used in a collaboration among NOAA, DOE, NSF, and other agencies to develop process-oriented diagnostics that help scientists understand and address model errors. Software was developed through a collaboration among scientists at NCAR, NOAA, DOE, and NASA laboratories, as well as academic institutions.

Collaboration on model development has also continued in the interagency space. One such activity initiated in 2019 involves scientists from NOAA, NASA, NCAR, and DOE, who are collaborating with the academic community on new Climate Process Team (CPT) efforts. These activities represent coordinated efforts by observational scientists, process theoreticians, and modelers to improve the representation of land surface and ocean processes in climate models. This CPT method of improving climate models was originally pioneered by NSF and has since expanded to a multi-agency consortium. CPT efforts have yielded significant advances in climate models through collaboration among Federal agencies and with the non-federal scientific community. This work is also supportive of the U.S. Global Energy and Water Exchanges (GEWEX) effort coordinated through USGCRP.