Absorbing aerosol choices influence precipitation changes across future
Future precipitation changes are controlled by the atmospheric energy
budget, with temperature, water vapor, and absorbing aerosols playing
dominant roles in driving radiative changes. 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.