Sunday, July 15, 2012

Tibetan glaciers shrinking rapidly

Jane Qiu in Nature: The majority of glaciers on the Tibetan plateau and in the surrounding region are retreating rapidly, according to a study based on 30 years of satellite and field measurements. The research by Yao Tandong, a glaciologist at the Chinese Academy of Sciences' Institute of Tibetan Research in Beijing, and his colleagues is published today in Nature Climate Change. It “is the most comprehensive survey to date in the region”, says Tobias Bolch, a glaciologist in the University of Zurich, Switzerland.

The Tibetan plateau and the bordering mountain ranges, including the Himalayas, the Karakoram, the Pamir and the Qilian make up a vast region known as the Third Pole, home to 100,000 square kilometres of glaciers that supply water to about 1.4 billion people in Asia.

The status of the glaciers has been a point of contention. Earlier this year, an analysis of 7 years' worth of measurements taken by the Gravity Recovery and Climate Experiment (GRACE) satellite mission suggested2 that high-altitude Asian glaciers on the whole are losing ice only one-tenth as fast as previously estimated, and that glaciers on the Tibetan plateau are actually growing.

Yao and his colleagues analysed satellite measurements of the lengths and surface areas of about 7,100 glaciers. They also studied changes in the mass balance — the difference between accumulation and loss of ice — of 15 glaciers that they have painstakingly measured for decades.

 “The majority of the glaciers have been shrinking rapidly across the studied area in the past 30 years,” says Yao. And the rate of retreat has been accelerating. But embedded in this general trend, says Yao, is a large variation in different parts of the Third Pole. For instance, glaciers in the Himalayas are retreating faster on average than those in the Karakoram and the Pamir....

Laigu glacier in Tibet, shot by Jiangmy, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

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