Himalayan water supply gets an improved outlook

Meltwater pond on Lirung Glacier.

Evan Miles

Glaciers are very sensitive to changes in climate, making them clear (even visually striking) indicators of the recent warming trend. Apart from raising sea level and threatening to turn the name of Glacier National Park in the US into a sad irony, the loss of glacial ice can also endanger water availability.

The seasonal melting of mountain glaciers (and snowpack) provides an important source of water in most places where they can be found. The Indus, Brahmaputra, and Ganges Rivers in India, and the Yellow and Yangtze Rivers in China, are particularly noteworthy examples of rivers with headwaters that are fed by glacial melt high in the Himalayas.

Those rivers supply water to a staggeringly large number of people, so the impact of climate change on Himalayan glaciers has understandably been the focus of study. As a glacier shrinks, the amount of meltwater it produces increases for a while before the diminishing volume of ice wins out, causing melt to dwindle.