Multi-Model Future World Aridity and Groundwater Recharge Changes With and Without Stratospheric Aerosol Intervention Under High Warming Scenario

Groundwater recharge (GWR) would affect by stratospheric aerosol injection (SAI)—a proposed solar geoengineering method. Using six Earth-system models from the G6Sulfur experiment, offsetting Shared-Socioeconomic-pathway SSP5-8.5 warming to SSP2-4.5 levels, we assess aridity and GWR responses over 2070–2099. SAI reduces global aridity (+25.4% to +9.1%) but fails in GWR restoration (from −7.7% under SSP5-8.5 to −7.6% under G6Sulfur) due to sustained evapotranspiration (+7–25%). Recharge deficits persist or intensify in the Mediterranean, northern midlatitudes, southern Africa, and northeastern Brazil, while partial gains remain in India, the Sahel, southern Arabia, western China, and southern South America, reflecting a “wetter/colder-get-drier and drier-get-wetter” pattern. GWR sensitivity to precipitation and evapotranspiration declines by 12.0% and 14.1%. CESM2-WACCM and CNRM-ESM2-1 simulate the strongest partial recovery, while MPI-ESM1.2s, IPSL-CM6A-LR, and UKESM1-0-LL show weaker or over-suppressed responses. Results highlight regionally incomplete and model-dependent SAI effects on GWR and the key role of CO₂-physiological forcing.