Divergent Actual Evapotranspiration Trends Across Global Biomes at Multiple Temporal Scales

Abstract Global warming is not uniformly intensifying evapotranspiration across terrestrial Biomes rather, it is amplifying divergence between energy-limited and water-limited biomes. Analyzing 44 years (1980–2023) of GLEAM v4 ET estimates across 15 major terrestrial biomes, we show that most biomes (13 of 15) exhibit statistically significant positive ET trends (p < 0.05), with humid forest biomes and tundra accelerating water loss at rates of + 0.8 to + 1.46 mm yr⁻¹. In contrast, temperate grasslands and deserts exhibit declining ET (up to − 0.15 mm yr⁻¹), suggesting water supply constraints despite warming. This divergence peaks during Northern Hemisphere spring and summer, when temperate forests show accelerating ET trends of + 2.5 mm decade⁻¹ during May–August—equivalent to ~ 15% of their baseline warm-season ET. Critically, ET responses vary even within water-limited biomes: tropical grasslands show moderate increases (+ 0.28 mm yr⁻¹), contrasting sharply with declines in temperate grasslands and deserts, indicating divergent water availability controls. Unlike previous global-scale studies that aggregate across climate zones, our biome-resolved, multi-decadal analysis reveals that anthropogenic warming is driving divergent ET responses across terrestrial biomes, intensifying water loss in humid Biomes while exacerbating water scarcity in already-stressed drylands. These findings challenge assumptions of uniform hydrological intensification and provide observational constraints for Earth system models and adaptive water management strategies.