Deep ocean heat content is key to estimating Earth's radiation balance

Abstract

Despite the fact that average temperatures on land have been increasing from year to year, globally averaged surface temperatures from 2000 to 2010 have shown only moderate warming. This is because sea surface temperatures over the past decade have been flat, if not slightly decreasing. In light of this, scientists are curious about whether this reduced rate of surface warming indicates a reduction of the accumulation of heat in the Earth system over the same period. Palmer et al. used multicentury climate model simulations to study the relationships among decadal trends in top‐of‐atmosphere radiation balance (which controls the heat content of the Earth system), ocean heat content, and surface temperature. Consistent with previous studies, they found that all models show large variability in sea surface temperature (SST). This large internal variability in SST could easily “mask the anthropogenic warming signal for a decade or more,” the authors note. By contrast, ocean heat content more closely tracks the radiation budget at the top of the atmosphere, suggesting that measurements of ocean heat to deeper levels would help us monitor climate change more accurately. (Geophysical Research Letters, doi:10.1029/2011GL047835, 2011)