Vigorous ice streams transport mass of the Greenland Ice Sheet towards the ocean. In contrast to Antarctica, large ice shelves are missing at the coast, but the calving fronts are in direct contact with the ocean. Depending on bottom topography, ice at the fronts can be several hundred meters thick, though only 1/10 is visible above sea level. At the base, warm and salty Atlantic Water, which is denser than the cold and fresh Polar Water, melts the ice.
During the last two decades, an enhanced retreat of many Greenland glaciers has been observed. Ice sheet thinning and increased mass loss can be attributed not only to higher surface melting due to warmer air temperatures but also to larger basal melt rates caused by the arrival of warmer Atlantic Water at the calving fronts. Starting in the mid-1990’s, maximum glacier retreat occured along the west and southeast coast of Greenland, where water temperatures up to 4 degrees Celsius have been observed in fjords hosting the glaciers.
Thinning of glaciers in northern Greenland has been observed first in the mid-2000’s. At the north and northeastern coast, glacier termini tend to float on the ocean like small Antarctic ice shelves. In addition to the observed thinning, increased calving of icebergs caused either a substantial retreat of the floating glacier tongue or a total collapse like in northeast Greenland.
Scientists at AWI investigate ocean-glacier interaction at Greenland’s longest floating glacier – the 79-North Glacier also called Nioghalvfjerdsbreen. More information is provided following the links to GROCE und SPP-OGreen.