Transition in Global Basins From Precipitation‐Dominated to Evaporative Demand‐Dominated Meteorological Drought: Past Patterns and Future Projections

Abstract Meteorological drought, one of the most destructive natural hazards, is driven by both precipitation deficits and high evaporative demand. While precipitation has traditionally been considered the dominant driver, recent studies suggest an increasing influence of evaporative demand. However, it remains uncertain whether these findings represent individual regional cases or a boarder emerging global trend. To address this, we developed a systematic framework using a standardized precipitation evapotranspiration index (SPEI) variant experiment to attribute drought drivers across 292 major global basins. Our historical analysis (1970–2024) reveals a widespread global transition: 48.1% of the global basin area (6.43 × 10 7 km 2 ) transitioned from precipitation‐dominated to evaporative demand‐dominated drought. This transition, accelerating after 2000, originated in arid continental interiors and expanded outwards, leaving precipitation‐dominated areas only one‐tenth the size of evaporative demand‐dominated ones. Future projections from bias‐corrected coupled model intercomparison project phase 6 models indicate this transition is largely irreversible, as over 80% of historically transitioned basins are projected to maintain evaporative demand‐dominated through 2100. Basins that have not yet transitioned are also projected to transition toward either evaporative demand‐dominated or precipitation and evaporative demand co‐dominated drought states. Under the shared socioeconomic pathway (SSP) 5‐8.5 scenario, the global area of evaporative demand‐dominated droughts is projected to be 17.6% larger by 2100 than under SSP1‐2.6 scenario. These findings highlight the urgent need for both climate mitigation to slow these transitions and proactive adaptation to address the new reality of drought driven by evaporative demand.