Mountains are the water towers of the world, and researchers say that climate change is poised to alter water availability and food security in the major river basins of Southeast Asia in very substantial but diverse ways. Knowing that more than 1.4 billion people depend on water from the Indus, Ganges, Brahmaputra, Yangtze, and Yellow Rivers, Walter Immerzeel and colleagues (from FutureWater and the University of Utrecht) set out to investigate how global warming will likely affect the upstream snow and ice reserves that feed those basins with fresh water in the future. The researchers discovered that meltwater is extremely important to the Indus and Brahmaputra basins, but not so much to the to the Ganges, Yangtze, and Yellow rivers.

They also say that the Indus and Brahmaputra basins are the most susceptible to reductions in the flow of meltwater, which could threaten the food security of approximately 60 million people. Though they predict considerable changes in the cryosphere-the portions of the Earth’s surface where water is frozen-the authors also say that the impact of climate change on these Asian river basins will probably be less than previous predictions. Still, Immerzeel and his team estimate that the food security of 4.5 percent of the total population of Asia will be threatened as a result of reduced water availability, and they argue that the need for increasing water productivity is more important now than ever before.

Read more in Science 11th June 2010 .