Climate change is altering the natural water cycles in South Asia. The consequences of melting glaciers diminish seasonal snow, and changes in precipitation pose significant risks to the stability of water resources in the region. Glaciers have been crucial to the balance of the ecosystem: they help to moderate flows in the region’s major rivers by providing a source of meltwater in hot, dry years and storing water during colder, wetter years. The Himalaya, Karakoram, and Hindu Kush mountain ranges of South Asia, which contain almost 55,000 glaciers, store more freshwater than anywhere but the North and South Poles.

The recent series of flash floods that killed dozens of people and left hundreds missing in the Himalayas was far from the first such disaster to occur among the world’s high-mountain glaciers. In a world with a changing climate, it will not be the last. With the shrinking and thinning of glaciers, it is clear that communities and entire sectors of industry are being—and will continue to be—impacted by the changes in water supply. Farmers and indigenous peoples will be hit the hardest as droughts, floods, and weather fluctuations disrupt crop production and alter the livelihoods of those who live downstream. Many of the 750 million people living in the basins of the three mighty rivers of the region—the Indus, the Ganges, and the Brahmaputra—derive their livelihoods primarily from agriculture, which, in turn, feeds the region’s urban communities. Water from the headwaters of these rivers contributes significantly to energy production and recreation in the region.