Coordinated experiments run across major Earth system models help improve model projections and advance climate science understanding.

Projections of the future state of the Earth system can differ significantly across models, with various potential sources of uncertainty. To better understand the sources of difference and where fundamental scientific understanding can be improved, the Earth system modeling community uses a set of experiments run across many models known as the Coupled Model Intercomparison Project (CMIP). CMIP is an ongoing effort, now in its sixth phase (CMIP6), and is supporting several projects that address key areas of uncertainty in future climate projections: radiative forcing (RFMIP), cloud feedbacks (CFMIP), and ice sheet behavior (ISMIP6). Results from these projects will be shared openly with the global scientific community and will contribute to improved model projections and understanding of the causes for differences across model projections.

RFMIP is a newly-established international effort supported by DOE, NOAA, the Office of Naval Research, and NASA in the United States, with contributions from climate modeling efforts worldwide. The project establishes protocols for accurately determining radiative forcing—a measurement of human and natural factors that influence Earth’s energy balance and climate—and for using this improved skill to improve models and better understand the role of atmospheric aerosols and greenhouse gases in the climate system.