Climate change threatens terrestrial water storage over the Tibetan Plateau

The Tibetan Plateau is an important source region of freshwater for large parts of Asia's population. Here the authors quantify past and future terrestrial water-storage changes and find a large net loss in this region, with the Amu Darya and Indus basins as the most vulnerable hotspots. Terrestrial water storage (TWS) over the Tibetan Plateau, a major global water tower, is crucial in determining water transport and availability to a large downstream Asian population. Climate change impacts on historical and future TWS changes, however, are not well quantified. Here we used bottom-up and top-down approaches to quantify a significant TWS decrease (10.2 Gt yr(-1)) over the Tibetan Plateau in recent decades (2002-2017), reflecting competing effects of glacier retreat, lake expansion and subsurface water loss. Despite the weakened trends in projected TWS, it shows large declines under a mid-range carbon emissions scenario by the mid-twenty-first century. Excess water-loss projections for the Amu Darya and Indus basins present a critical water resource threat, indicating declines of 119% and 79% in water-supply capacity, respectively. Our study highlights these two hotspots as being at risk from climate change, informing adaptation strategies for these highly vulnerable regions.