Nature - Study Shows Karakoram Glaciers Gaining Mass, But Total Gains Slight
While most of the world’s glaciers are shedding ice at a brisk clip, many in one mountain range along the rim of the Tibetan plateau have been posting measurable gains in recent years, a new study confirms1. The finding comes just as researchers get set to launch a long-term international effort to study in detail 25 Tibetan glaciers (see 'Glaciologists to target third pole') — a small sample of the 46,000 ice masses that supply water to some 1.4 billion people in central and southern Asia.
On the basis of field studies of glaciers in the Karakoram mountain range, which straddles China’s border with India and Pakistan, researchers suggested in 2005 that the ice masses there might actually be growing2. Subsequent analyses of satellite images hinted that many glaciers in the region were spreading to cover more area, but it was not clear whether the ice masses were simultaneously becoming thinner and therefore losing ice overall. The new study, published today in Nature Geoscience, looks at trends in both ice coverage and thickness and finds that in the central Karakoram the glaciers are indeed becoming heftier, if only slightly.
The researchers, led by glaciologist Julie Gardelle of the University of Grenoble in France, estimated changes in the thicknesses of glaciers across a 5,615-square-kilometre area by comparing data gathered during two space-based surveys — one by instruments aboard the Space Shuttle Endeavour in February 2000 and the other by France’s SPOT5 satellite in December 2008. After accounting for differences in orbital paths of the two craft and the different times of year at which data were gathered, among other factors, the team estimated that in each year from late 1999 to late 2008 the region’s glaciers, on average, gained a thickness of ice that if melted would yield about 11 centimetres of water.
The team has addressed all known problems to ensure that the two data sets are comparable, says Graham Cogley, a glaciologist at Trent University in Peterborough, Ontario, who wrote an accompanying News and Views on the paper. “This is a solid, high-grade measurement,” he notes.
EDIT
http://www.nature.com/news/renegade-glaciers-gain-ice-1.10448
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