Anthropogenic Forcings Intensify Droughts More Severely in Drylands than in Humid Regions

Abstract Droughts of different durations affect water resources and ecosystems in distinct ways. Human activities have been confirmed to contribute to the increased occurrence of droughts; however, the dependence of these impacts on the durations of drought, and whether they differ between drylands and humid regions, remains insufficiently understood. This study investigates the human influence on droughts of different durations using the Standardized Precipitation Evapotranspiration Index (SPEI), derived from multi‐source observations and four sets of Coupled Model Intercomparison Project Phase 6 (CMIP6) multi‐model simulations. The results show that human activities cause an intensification of long‐term droughts, particularly in drylands. This is primarily attributed to rising greenhouse gas (GHG) emissions, with both GHGs and aerosols exerting stronger impacts on droughts in drylands than in humid regions, though aerosols partly offset the intensifying effect. GHGs contribute to more extreme multi‐year droughts over drylands by amplifying temperature‐induced water demand, whereas aerosols reduce drought occurrence in drylands by enhancing precipitation, in contrast to their precipitation‐suppressing effects in humid areas in the past decades.