Climate Change Will Affect the Asian Water Towers

Towering Figures The Tibetan plateau and adjacent mountain ranges are the source areas of the five major rivers of Asia. Climate change promises to affect both precipitation patterns and glacial melting in the region, which could have marked impacts on river flows and on associated agriculture. Immerzeel et al. (p. 1382) analyzed the relative importance of glacial meltwater and rainfall in the region in order to determine how the rivers depend on different sources of water, and how the river basins may be affected by climate change. Climate change is likely to affect water availability in the river basins in substantial but diverse ways, which may threaten the food security of tens of millions of people. Climate change will cause substantial but diverse changes in water availability in the major river basins of Southeast Asia. More than 1.4 billion people depend on water from the Indus, Ganges, Brahmaputra, Yangtze, and Yellow rivers. Upstream snow and ice reserves of these basins, important in sustaining seasonal water availability, are likely to be affected substantially by climate change, but to what extent is yet unclear. Here, we show that meltwater is extremely important in the Indus basin and important for the Brahmaputra basin, but plays only a modest role for the Ganges, Yangtze, and Yellow rivers. A huge difference also exists between basins in the extent to which climate change is predicted to affect water availability and food security. The Brahmaputra and Indus basins are most susceptible to reductions of flow, threatening the food security of an estimated 60 million people.