Forcing dataset updates impact regional but not global Earth radiation budget trends in the GFDL AM4 climate model

The availability of up-to-date forcing datasets is critical for reconciling Earth system model simulations with contemporary observations. With the newly released CMIP7 forcing dataset, which extends the historical record through 2021, this study provides a systematic evaluation of how using updated forcings over the “middle-of-the-road” SSP2-4.5 scenario forcings influences the simulated radiation budget in the GFDL AM4 climate model. The updated forcing dataset used in the atmosphere model does not improve the agreement between the simulated global-mean top-of-the-atmosphere radiation trends and the satellite-observed trends. Regionally, we identify pronounced shifts in radiative energy partitioning between atmosphere and surface. Specifically, during 2001–2021, accelerated reductions in sulfate and black carbon aerosols over East Asia drive a significant decline in atmospheric solar absorption that matches observations, while a substantial increase in organic aerosols at higher latitudes induces a localized increase in atmospheric absorption that does not match observations. The substantial influence of localized forcing changes on simulated regional climate underscores the necessity for routine updates of forcing datasets.