Loss of ice volume doubles in just 5 years
By Bob Berwyn
FRISCO —Detailed new data from satellites and other sources show the world’s major ice sheets losing volume at a record pace, faster than at any time since satellite measurements started about 20 years ago.
Since 2009, the rate of volume loss from the Greenland Ice Sheet has doubled, and the rate of volume loss from the West Antarctic Ice Sheet has tripled, according to the new findings from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.
Ice sheets gain mass through snowfall and lose it due to melting and accelerating glaciers, which carry ice from the interior of the ice sheet to the ocean.
“We need to understand where and to which extent the ice thickness across the glaciers has changed. Only then can we can analyse the drivers of these changes and find out how much ice sheets contribute to global sea level rise,” said glaciologist Dr. Veit Helm, lead author of the study.
The new maps showing the volume of the key ice sheets were produced using more than 200 million data points for Antarctica and about 14.3 million data points for Greenland. The results reveal that the Greenland Ice Sheet alone is losing about 375 cubic kilometers of ice each year.
Satellite altimeter measure 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.
The areas where the researchers detected the largest elevation changes were Jakobshavn Isbrae (Jakobshavn Glacier) in West Greenland and Pine Island Glacier in West Antarctica.
Scientists know that the Jakobshavn Isbrae is moving ice into the ocean at a record speed of up to 46 meters a day. The Pine Island Glacier hit the headlines in July 2013, whe a city size iceberg broke off the tip of its ice shelf.
But whereas both the West Antarctic Ice Sheet and the Antarctic Peninsula, on the far west of the continent, are rapidly losing volume, East Antarctica is gaining volume – though at a moderate rate that doesn’t compensate the losses on the other side of the continent.