Record decline in ice sheets in Antarctic and Greenland

Digital maps created with satelllite data show the combined volume of ice loss in Greenland and west Antarctic is 500 km3

By Aruna P Sharma
Published: Friday 22 August 2014


New digital maps created by scientists in Germany on the current state of ice sheets in the Antarctic and Greenland show unprecedented thinning of ice.

The new maps reveal the ice sheets are losing volume at an annual rate of about 500 cubic km, say the the study findings and maps, which were recently published in The Cryosphere.

"The new elevation maps are snapshots of the current state of the ice sheets,” says lead-author Veit Helm, glaciologist at the Alfred Wegener Institute (AWI) in Bremerhaven in a press release. “The elevations are very accurate, to just a few metres in height, and cover close to 16 million km2 of the area of the ice sheets. This is 500,000 square kilometres more than any previous elevation model from altimetry," he adds.

For creating the digital maps, the scientists looked at data from European Space Agency’s (ESA) CrysoSat-2 spacecraft altimeter SIRAL. Satellite altimeter measures the height of an ice sheet by sending radar or laser pulses in the direction of the earth. These signals are then reflected by the surface of the glaciers or the surrounding waters and are subsequently retrieved by the satellite. This way the scientists were able to precisely determine the elevation of single glaciers and to develop detailed maps, says the press release.

The team derived the elevation change maps using over 200 million SIRAL data points for Antarctica and around 14.3 million data points for Greenland.  They compared the current data with those from the ICESat satellite from the year 2009 and found the volume loss in Greenland has doubled since then. The loss of the West Antarctic Ice Sheet has in the same time span increased by a factor of 3. “Combined, the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest rate observed since altimetry satellite records began about 20 years ago," says AWI glaciologist Angelika Humbert, co-author of the study.

East Antarctica, however, was found to be gaining volume, though at a moderate rate, which the scientists said is not enough to compensate the losses on the other side of the continent.

Mark Drinkwater, ESA’s CryoSat Mission Scientist, noted, “These latest results offer a critical new perspective on the recent impact of climate change on the large ice sheets.” This is particularly evident in parts of the Antarctic peninsula, where some of the more remarkable features add testimony on the impact of sustained peninsula warming at rates several times the global average,” he adds.


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