Tibetan Glaciers Growing Against the Flow

Published on April 17th, 2012 | by

April 17th, 2012 by

Despite glaciers across the planet melting at an accelerated and unprecedented rate, one mountain range along the rim of the Tibetan plateau is home to a series of glaciers that have actually been posting measurable gains over the past decade.

The Karakoram mountain range straddles China’s border with India and Pakistan, and was the focus of a 2005 study that saw researchers suggest that ice masses there may in fact have been growing, rather than decreasing along with the average.

Karakoram Mountains (Pakistani side)

The researchers led by glaciologist Julie Gardelle of the University of Grenoble in France analysed satellite images gathered by instruments abord the Space Shuttle Endeavour in February of 2000 and from France’s SPOT5 satellite in December of 2008. They confirmed that the Karakoram glaciers, on average between 1999 to 2008, gained a thickness of ice that if melted would have produced approximately 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 which was published in the most recent edition of the journal Nature Geoscience. “This is a solid, high-grade measurement,” he notes.

“There’s no question that Karakoram glaciers are holding their own, but exactly why that is, we don’t know,” says Kenneth Hewitt, a geographer at Wilfred Laurier University in Waterloo, Ontario. The new study pins down recent trends in ice thickness in the region but doesn’t reveal why they are changing, he adds.

 Some scientists have suggested that thick layers of rocky debris smothering some parts of the Karokoram’s glaciers — the results of frequent avalanches — are insulating the glaciers, protecting them from the same warmth that afflicts glaciers elsewhere3. But the new data reveal that ice loss for these glaciers at lower elevations is the same in debris-covered areas as it is where the ice and snow are clean, says Gardelle.
There has in fact been several studies hinting at the possibility that the climate in the Karakoram mountains may be cooling. Records from weather stations between 1961 and 2000 showed that there had been an increase in winter precipitation and a decrease in average temperatures during the summer. Additionally, during the same 40 year period, average flow volume for one of the meltwater rivers was 20 percent below normal.

But on the whole, Gardelle says, “we have no idea what’s behind the odd behaviour of these glaciers, or when it started”. Moreover, she notes, researchers have no clues about whether the Karakoram glaciers will continue to accumulate ice in coming decades.

Source: Nature
Image Source: Guilhem Vellut

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