Petermann Glacier in Greenland shows ice loss

Scientists from the Byrd Polar Research Center at Ohio State University have compiled dramatic new evidence of ice loss from Greenland’s glaciers over the past decade. The single most extreme loss – from Petermann Glacier – is the largest in the observational record for Greenland.

The data show that 39 glaciers in Greenland have collectively lost 535 square kilometers (207 square miles) of ice over the past decade. The single most extreme loss was due to a large chunk of ice four times the size of Manhattan Island in New York City. The ice broke off from the Petermann glacier over a period of three days in early August, 2010.

The ice lost from the Petermann glacier measured 290 square kilometers (112 square miles) in size and caused the glacier to retreat by an impressive 18 kilometers (11 miles).

To get these results, the Byrd Polar Research Center scientists chose 39 of Greenland’s widest marine-terminating glaciers and analyzed satellite imagery from them over the past 10 years (2000 to 2010). The imagery was obtained from NASA’s MODIS program. MODIS (Moderate Resolution Imaging Spectroradiometer) is a type of instrument aboard the Terra and Aqua satellites that collects vital information on global dynamics and processes occurring on the land, in the oceans and in the atmosphere.

In an August 31, 2011, press release, lead author Jason Box, associate professor of geography at Ohio State University, commented:

The August 2010 ice calving at Petermann is the largest in the observational record for Greenland.

The calving event is also thought to be the largest to occur throughout the entire Arctic since 1962.

On July 24, 2011, Box’s colleague Alun Hubbard from the Center for Glaciology at Aberystwyth University in the UK embarked on a polar expedition to photograph the Petermann glacier. Hubbard stated:

Although I knew what to expect in terms of ice loss from satellite imagery, I was still completely unprepared for the gob-smacking scale of the breakup, which rendered me speechless … What the breakup means in terms of inland ice acceleration and draw-down of the ice sheet remains to be seen, but will be revealed by the GPS data recovered, which we are now processing at Aberystwyth.

Unfortunately, the scientists have detected a rift upstream of the 2010 break point suggesting that the next loss from the Petermann glacier could be as large as 150 square kilometers (58 square miles). The Petermann glacier is one of only a few remaining floating glaciers in the Northern Hemisphere.

Some of the other glaciers studied were in better shape. In total, of the 39 glaciers analyzed in Greenland, 37 percent were stable, 19 percent had advanced and 44 percent were retreating.

The scientists believe that the overall destabilization of Greenland’s ice sheets over the past decade was caused primarily by warming ocean waters and that increased surface melting played a smaller part of the story.

Glacial retreat is expected to cause significant sea level rises and problems for coastal communities over the next century.

The research documenting the vast ice loss from Greenland’s glaciers over the past decade was funded in part by the U.S. National Science Foundation and was published (PDF) in the summer 2011 issue of the Annals of Glaciology.

Polar researchers: Arctic now reinforcing own warming

Melting polar ice now largest contributor to sea level rise

Robert Bindschadler on what ice sheets reveal about climate