On a summer day in the mountains high above Almaty, Kazakhstan’s largest city, the Tuyuksu glacier is melting like mad. Rivulets of water stream down the glacier’s thin leading edge.
As she has for nearly two decades, Maria Shahgedanova, a glaciologist at the University of Reading in England, has come here to check on the Tuyuksu. As one of the longest-studied glaciers anywhere, the Tuyuksu helps gauge the impact of climate change on the world’s ice.
With colleagues from the Kazakhstan Institute of Geography, Dr. Shahgedanova has made the slow trip from Almaty, 15 miles to the north and nearly two miles below, lumbering up a steep, rutted mountain road in a giant Russian utility vehicle.
Last year, at the end of the summer melting season, the team drew lines on the stakes marking the height of the ice, as researchers have done here for decades. Now, looking at a stake nearly a year later, Nikolay Kasatkin, one of the institute researchers, and Dr. Shahgedanova saw that more of the wood was visible. With the end of melting still a couple of months off, parts of the Tuyuksu were already about three feet thinner.
Glaciers represent the snows of centuries, compressed over time into slowly flowing rivers of ice, up to about a thousand feet thick here in the Tien Shan range and even thicker in other parts of the world. They are never static, accumulating snow in winter and losing ice to melting in summer. But in a warming climate melting outstrips accumulation, resulting in a net loss of ice.
The Tuyuksu, which is about a mile and a half long, is getting shorter as well as thinner. When the research station was built in 1957 it was just a few hundred yards from the Tuyuksu’s leading edge, or tongue. Now, reaching the ice requires scrambling on foot for the better part of an hour over piles of boulders and till left as the glacier retreated.
What’s happening in the mountains of southeastern Kazakhstan is occurring all over the globe.
The world’s roughly 150,000 glaciers, not including the large ice sheets of Greenland and Antarctica, cover about 200,000 square miles of the earth’s surface. Over the last four decades they’ve lost the equivalent of a layer of ice 70 feet thick.
Most of them are getting shorter, too. Some have shrunk to nothing: Smaller glaciers in places like the Rockies and the Andes have disappeared. Even if greenhouse gas emissions were sharply curtailed immediately, there has already been enough warming to continue shrinking glaciers around the world.
This great global melting contributes to sea level rise. It affects production of hydroelectricity. It leads to disasters like rapid, catastrophic floods and debris flows. It alters rivers and ecosystems, affecting the organisms that inhabit them.
But here in the Tien Shan, the biggest impact may be on the supply of water for people and agriculture.