It’s the Heat and the Humidity: The Complementary Roles of Temperature and Specific Humidity to Recent Changes in the Energy Content of the Near‐Surface Atmosphere

Abstract

AbstractGlobal climate change is a change in the planetary energy (E) balance. It is usually expressed as a change in near‐surface air temperature (Ta), but changes in energy content due to Ta (ET) represent only part of the near‐surface energy balance, which also includes E changes due to specific humidity (ESH). We analyzed MERRA‐2 and ERA5 reanalysis data and 15 CMIP6 Atmospheric Model Intercomparison Project (AMIP) models from 1980 to 2014. Some 44%, 39%, and 50% of MERRA‐2 pixels showed significant increases in ET, ESH, and E, respectively. The average increase in ET (ESH) was 16.9 (13.6) J kg−1 year−1, but AMIP models estimated larger average ET (21.6 J kg−1 year−1) and ESH (16.7 J kg−1 year−1). Global Ta would have increased at nearly double the observed rate if energy was not partitioned into latent heat. Results demonstrate the critical role that specific humidity plays in recent climate changes.