Both India and Pakistan share a common major river, the Indus River. Nearly 30 percent of the world’s cotton supply comes from these countries, much of it from the river’s Valley. But important industries that require a large amount of water, such as textiles, sugar, and wheat from both of these populous countries, are sucking up the river, as well as Indian and Pakistani hydroelectric dam projects. But there is another factor at work here, reports William Wheeler for National Geographic News. Climate change is causing glaciers worldwide to shrink, and a full half of the Indus River flow is supplied by glaciers in the Indian Kashmir region, already a source of political tension between these two nuclear powers. As global warming accelerates glacial melting, unusually high spring runoff could cause catastrophic flooding, as Pakistan experienced in 2010. Water shortages in Pakistan have already triggered internal conflicts, creating food and energy crises that have ignited riots and protests in some cities. But booming populations in both countries and climate change may ignite a far more dangerous international tug of war over the shrinking Indus River.