Glaciers in the mountains of central Asia have lost a quarter their ice mass over the last 50 years, tied to increased melting during rising summer temperatures, researchers say.
The loss from the glaciers of Central Asia's Tien Shan mountain range is extreme enough to raise concerns about the security of the water supply for people living in that part of China, Turkmenistan, Kyrgyzstan, Kazakhstan and Uzbekistan, they warn. Residents in the arid region depend upon glacier meltwater for drinking water.
The glaciers in the Tien Shan range, which stretches across 1,500 miles, are particularly vulnerable because winters in the range are especially cold and dry with hardly any snow, the researches report in the journal Nature Geoscience.
There is some snowfall in summer, but with climate change and global warming there's less of it and more subsequent melting, say study lead author Daniel Farinotti, a glaciologist at the GFZ German Research Center for Geosciences in Potsdam, Germany.
"You're double-hitting the glacier – that is why they're so sensitive to changes in temperature," he explains.
The future doesn't bode well, say the researchers, who predict half the remaining ice in the Tien Shan range could be lost by 2050.
That could impact the lowlands of Kazakhstan, Kyrgyzstan and Uzbekistan where water is critical for irrigation, and China's northwestern Xinjiang Uyghur autonomous region, home to oil, natural gas and coal reserves critical for the country's economic growth.
"If water resources really will decline there in the future, there is a big potential for conflicts," Farinotti says.
Using satellite observations, field studies and computer models, the researchers reconstructed the change in mass of the glaciers of the Tien Shan range, finding they shrank at an average rate of more than 5 billion tons a year.
With climate models suggesting an ongoing rise in summer temperatures in the decades ahead, there is little chance of halting that shrinkage without drastic action, Farinotti says.
"In the long term, the only way people are going to save glaciers is to reduce the increase of global temperatures," he says.
Although the melt in the Tien Shan region is four times the global average, the region is not alone in experiencing worrying glacial loss; the pattern has been seen in other parts of the world, the researcher notes.
The early 21st century has witnessed a "historically unprecedented" decline in glaciers worldwide, according to a recent study by the World Glacier Monitoring Service in Switzerland.
The decade from 2000 to 2010 saw the greatest 10-year glacier ice loss ever measured, it reported.