2026-02-20 ONE EARTH 2026 9(卷), 2(期), (null页)
Global runoff is a critical resource generated by the competition between precipitation and evapotranspiration. Aridity profoundly impacts vegetation's precipitation redistribution and evapotranspiration processes, thereby altering runoff. However, the specific aridity tipping points of these interactions remain poorly explored. Here, we quantify these distinct responses and identify their aridity tipping points using multi-source observations and modeling. We show that global total runoff increased by 6.83 mm during 2000-2020. Specifically, greening reduced runoff by 10.88 mm, while browning increased runoff by 3.16 mm; both are intensified in regions with aridity indices below 0.41 and 0.37, respectively. Through enhanced evapotranspiration, vegetation dynamics cumulatively offset 9.23 mm of the runoff increase, accounting for 29.20% of the total change and balancing precipitation's contribution by about 29.40%. The identified aridity tipping points in vegetation's regulation of runoff reveal non-linear responses, providing new insights for accurate water risk assessment and adaptation governance in drylands.
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