Abstract
Future precipitation changes are controlled by the atmospheric energy
budget, with radiative changes driven by temperature, water vapor, and
absorbing aerosol playing dominant roles. Atmospheric energy budgets are
calculated for different Shared Socioeconomic Pathways (SSPs) using
ScenarioMIP projections from phase 6 of the Climate Model
Intercomparison Project and are used to quantify the influence of 21st
century aerosol cleanup on precipitation. Absorbing aerosol influences
on shortwave absorption are isolated from the effects of water vapor.
Apparent hydrologic sensitivity is ~40% higher for the
Middle of the Road (SSP2-4.5) scenario with aerosol cleanup than
for the Regional Rivalry (SSP3-7.0) scenario that maintains
aerosol. Regionally, cleanup-induced changes in the atmospheric energy
budget are of a similar magnitude to the precipitation increases
themselves and are larger than the influence of changes in atmospheric
circulation. Policy choices about future absorbing aerosol emissions
will therefore have major impacts on global and regional precipitation
changes.