Divergent Causes of Terrestrial Water Storage Decline Between Drylands and Humid Regions Globally

Declines in terrestrial water storage (TWS) exacerbate regional scarcity and global sea level rise. Increasing evidence has shown that recent TWS declines are substantial ecologically fragile drylands, but the mechanism remains unclear. Here, by synergizing satellite observations model simulations, we quantitatively attribute trends during 2002–2016 major climate zones to three mechanistic drivers: variability, change, direct human activities. We reveal variability had transitory limited impacts (<20%), whereas warming-induced glacier loss activities dominate humid regions (?103%) drylands (?64%), respectively. In non-glacierized areas, generated gains offset synchronous declines. Yet losses enduring more widespread with activities, particularly unsustainable groundwater abstraction. Our findings highlight substantive footprints on already vulnerable arid an imperative need for improved dryland conservation.