GFDL-ESM2M developed over the last several years at the Geophysical Fluid Dynamics Laboratory (GFDL) of the National Oceanic and Atmospheric Administration (NOAA)。The models are the product of an effort to expand upon the capabilities of past models at GFDL that have been used to study issues of climate variability and change on seasonal to centennial time scales.The coupled climate models are composed of separate atmosphere, ocean, sea ice, and land component models, which interact through a flux coupler module.

The control simulations have stable, realistic climates when integrated over multiple centuries. Both models have simulations of ENSO that are substantially improved relative to previous GFDL coupled models. The CM2.0 model has been further evaluated as an ENSO forecast model and has good skill (CM2.1 has not been evaluated as an ENSO forecast model). Generally reduced temperature and salinity biases exist in CM2.1 relative to CM2.0. These reductions are associated with 1) improved simulations of surface wind stress in CM2.1 and associated changes in oceanic gyre circulations; 2) changes in cloud tuning and the land model, both of which act to increase the net surface shortwave radiation in CM2.1, thereby reducing an overall cold bias present in CM2.0; and 3) a reduction of ocean lateral viscosity in the extratropics in CM2.1, which reduces sea ice biases in the North Atlantic.

GFDL-ESM2M and GFDL-ESM2G having similar overall fidelity but having distinct differences. Among these, ESM2M warms with more thermocline ventilation, while ESM2G cools with more bottom water ventilation. While ESM2M has an overly vigorous El Niño–Southern Oscillation, ESM2G’s is weak.