Glaciers and Water Supplies

Mountain glaciers help regulate downstream water supplies by storing water over the long term and by releasing it every year during the warmest and driest months. Glaciers thus play a vital role in both the supply and timing of water for communities, farmers, ranchers, industries, and hydropower generators.

This topic of glaciers and water supplies has received extensive attention from researchers and the media, particularly for Himalayan glaciers. And yet the scenarios provided most often are vastly too simplistic: they assume downstream water conflicts based solely on the size of glaciers. Smaller glaciers means less water, as the stories usually run.

But shrinking glaciers at first release more water, not less. Once they have passed a point glaciologists and hydrologists call “peak water,” then the downstream water supply declines.

Even once the decline starts, however, it is people that determine the distribution and allocation of that water. Thus, policies, laws, water rights, money, social relations, and many other factors determines who gets the shrinking water supplies—and who does not.

Understanding these complex social-environmental dynamics in glacier-fed waterways thus requires collaboration among experts in many areas, from glaciology and hydrology to history, anthropology, law, policymaking, and many other areas. Innovation into approaches such as hydrosocial modeling offer one way to help bridge these multiple human and environmental forces that make adaptation to glacier retreat so complex, not simply an issue of climate change but of deeply rooted historical processes in specific communities and countries.

Glacier Tongue in Lake Llaca: Peru 2004 – Photo by Mark Carey.