Quantifying historical trends and future projections of evapotranspiration in arid central Asia using selected CMIP6 and GLEAM

Introduction The fragile social-ecological systems of Central Asia's arid regions (ACA) are critically dependent on evapotranspiration (ET) dynamics, which govern water and energy cycles in this precipitation-limited region experiencing increasing climatic variability and water stress. Methods Using the Global Land Evaporation Amsterdam Model (GLEAM) for historical analysis (1985-2014) and an optimized ensemble of five CMIP6 models (selected via DISO metric) under four SSP scenarios (SSP1-2.6 to SSP5-8.5) for future projections (2021-2100), this study provides a comprehensive assessment of ET trends and climate linkages. Results Key results show: (1) Historical ET increased significantly (0.43 mm/a by GLEAM; 0.98 mm/a by CMIP6 MME, p < 0.05); (2) Future projections reveal strongest ET increases under SSP5-8.5 (0.79 mm/a annually), with >85% of ACA (notably northern Kazakhstan and Kunlun Mountains) showing upward trends, though SSP1-2.6 causes growing-season declines in 48% of regions; (3) ET exhibits strong positive correlations with temperature (especially in Kyrgyzstan/Tajikistan/southern Xinjiang) and precipitation (r = 0.52 under SSP1-2.6). Discussion These findings underscore ET’s growing hydrological significance in ACA, highlighting the urgent need for adaptive water management strategies to address climate change impacts on agricultural, ecosystem sustainability and zoonics from one health perspective.