Saturday, August 8, 2009

A disappearing French glacier

Science Daily: Located over 12 000 kilometers from the Alps, the Kerguelen Islands are home to the largest French glacier, the Cook ice cap (which had an area of around 500 km2 in 1963). By combining historical information with recent satellite data, the glaciologists at the Laboratory for Space Studies in Geophysics and Oceanography (Université Paul Sabatier / CNRS / CNES / IRD) have observed increasingly rapid shrinkage of the ice.

Over the last 40 years, the Cook ice cap has thinned by around 1.5 meters per year, its area has decreased by 20%, and retreat has been twice as rapid since 1991. Their work has been just published in the Journal of Geophysical Research.

The Kerguelen Islands are located in the southern Indian Ocean, and numerous glaciers cover the highest areas of the islands. The first studies carried out in this exceptional natural laboratory for French research showed an initially slow retreat of the Ampère glacier (one of the outlet glaciers of the Cook ice cap) between 1800 and 1965, subsequently becoming much faster. Since 1974, in situ monitoring of the Cook ice cap has no longer been carried out. However, observations made from space between 1991 and 2006 have enabled scientists to collect data from this relatively inaccessible area.

…The glaciers in the Kerguelen islands were already retreating in the 1960s, and their decline over the past 40 years cannot be attributed only to recent warming partly due to human activities. Part of this retreat can in fact be explained by a delayed response of these glaciers to the natural warming that followed the Little Ice Age (a cold period that ended between 1850 and 1900). However, the recent acceleration of ice wastage is doubtless connected to high temperatures and low precipitation since the beginning of the 1980s.

Cook Glacier on Kerguelen Island, shot by B.navez, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License

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