Stratospheric Aerosol Injection Geoengineering Would Mitigate Greenhouse Gas‐Induced Drying and Affect Global Drought Patterns

Abstract

AbstractStratospheric aerosol injection (SAI) is suggested as a potential measure for alleviating global warming. The potential effects of SAI on global temperature and precipitation have been extensively discussed, but its impact on drought has received little attention. Based on the simulations from the G6sulfur experiment that employs SAI to reduce the global mean surface temperature from the level of high‐tier forcing (Shared Socioeconomic Pathways SSP5‐8.5) scenario to that of medium‐tier forcing (SSP2‐4.5) scenario, we investigate the drought response to SAI via the standardized precipitation evapotranspiration index. During 2081–2100, SAI effectively offsets the greenhouse gas‐induced aridity trend by increasing the climate water balance at the global scale. Drought duration and severity decrease but drought frequency increases under SAI forcing. Robust wetting responses occur over most regions, especially the Sahara, South America, southern Africa and Australia, while Alaska, Greenland, Southeast Asia, and tropical Africa face enhanced drought due to SAI. Relative to the SSP2‐4.5 scenario, the regional drying and wetting patterns in G6sulfur are remarkably different. Notably, in tropical Africa, SAI reverses the wetting caused by greenhouse gases and induces severer drought. The drought pattern changes are largely due to evaporative demand alterations caused by the vapor pressure deficit response.