[세미나] Dr. Julio Bacmeister

Climate Sensitivity in the Community Earth System Model (CESM)

Climate sensitivity refers to the response of the climate system to a doubling of atmospheric CO2. Equilibrium climate sensitivity (ECS), the long-term change in global mean surface temperatures after an abrupt increase in CO2, is an important metric for comparing different coupled climate models, as well as for evaluating individual climate models as they incorporate new physical parameterizations. This talk will examine ECS in two versions of the Community Earth System Model (CESM). The most recent round of the Climate Model Intercomparison Project (CMIP6) revealed dramatic increases in ECS for many leading climate models including CESM. Our analysis will show that increased ECS in CESM2, the most recent version of CESM can be traced to changes in the behavior of Southern Ocean clouds as well as tropical clouds. Finally, we will present new results from paleoclimate studies that suggest the climate sensitivity of CESM2 is indeed too high.