A water crisis looms for 270 million people as South Asia’s glaciers shrink

By Alice Albinia

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Rivers emerging from the eastern Himalaya, like the Brahmaputra, are mostly fed by the summer monsoon; their flow may well increase as a warming climate puts more moisture in the atmosphere. But most water in the Indus, which flows west from Mount Kangrinboqe, comes from the snows and glaciers of the Himalaya, the Karakoram, and the Hindu Kush. Glaciers especially are “water towers”: They store winter snowfall as ice, high in the mountains, and they surrender it as meltwater in spring and summer. In this way, they provide a steady flow that nourishes humans and ecosystems. Downstream, in the plains of Pakistan and northern India, the world’s most extensive system of irrigated agriculture depends on the Indus. The glaciers that feed it are a lifeline for some 270 million people.

Most of those glaciers are now shrinking. At first, that will increase the flow in the Indus. But if temperatures rise as predicted, and the glaciers continue to melt back, the Indus will reach “peak water” by 2050. After that, the flow will decline.

Humans already use 95 percent of the Indus, and the population of the basin is growing fast. Writing recently in the journal Nature, an international group of scientists (supported by the National Geographic Society) analyzed glacial water towers worldwide. The Indus is the most critical, they said: Given the region’s “high baseline water stress and limited government effectiveness,” it is “unlikely that the Indus … can sustain this pressure.” Pakistan will suffer most.

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