Sensitivity of Earth's Radiation Budget to Lower Boundary Condition Data Sets in Historical Climate Simulations

Abstract Atmospheric general circulation models are important tools to study climate change. A routine vindication for these models is to compare simulations with prescribed historical sea surface temperature (SST) and sea ice (SI) fraction against observations. Here, we report significant differences in the Earth's radiation budget in an Atmospheric general circulation model prescribed by different SST/SI data sets. This is caused by the distinct trends across different SST/SI data sets over the past decades despite all being based on observations. In particular, one data set reports a double rate of warming and an abrupt increase in SI coverage compared to the others. When using this data set as the boundary condition, the simulation predicts Earth's energy loss, in contrast to the observed energy gain. Our study calls for awareness of the impact of SST/SI data set uncertainty on radiation trends, especially for multimodel comparison projects, including CERESMIP and CMIP7.