Researchers have discovered a significant ice cap melt in Greenland, recording the biggest indication of climate change to date, as NASA releases the first high-quality images of a massive ice shelf, four times the size of Manhattan, that broke free last week.
The team from the Universities of St Andrews, Aberystwyth and Ohio State, were ‘amazed, but not shocked’ to monitor the breakup of a huge portion of the floating ice shelf off the front of one of the largest glaciers in the region.
The discovery of the breakup of a 250km sized berg follows a record melt in Greenland accompanied by the large scale breakup and retreat of the ice sheet's largest outlet glaciers.
University of St Andrews' researcher Richard Bates joined forces with colleagues Alun Hubbard (Aberystwyth University) and Jason Box (Byrd Polar Research Centre, Ohio State University) to investigate the effects of an abnormally high climate and oceanic warming on ice sheet melt and retreat across Greenland's most northern coastline.
Despite predicting the breakup of the Petermann Glacier following an earlier visit in 2009, the scientists had not envisaged it on such a vast scale.
Dr Bates commented, “We went up there last year as we suspected that there would be a breakup event in the near future. We believe that the melt water entering these fractures is quite critical to break up together with the warmer oceanic waters that come up from down south throughout the summer.
“It is not a freak event and is certainly a manifestation of warming. This year marks yet another record breaking melt year in Greenland; temperatures and melt across the entire ice sheet have exceeded those in 2007 and of historical records. Jakobshavn Isbrae – the world’s fastest flowing outlet glacier – also experienced a significant melt last month.”
Dr Bates is the geophysicist of the crew, responsible for the geophysical measurements through and around the glacier. At Petermann, this specifically extends to measuring the oceanic conditions in front of the glacier and importantly beneath the glacier along the fractures.
Petermann Glacier is one of Greenland’s largest outlet glaciers which is 20km wide at its front and has a catchment area covering 8% of the entire Greenland ice sheet. It is also the largest floating ice shelf in the northern hemisphere which is fed, like a massive conveyor, by ice flowing from the grounded inland ice sheet.
Deploying time-lapse cameras overlooking the glacier from the top of its towering 900m cliffs, the research team can record the dramatic event and determine whether the breakup has led to a further acceleration and thinning of ice. All going well, the scientists will return later this month to gather recorded data and to carry out further investigations.
Dr Bates continued, “It is very difficult logistically and expensive to get back. The idea at present is to try and sail to close to the glacier with helicopter support on the passage up there and then for getting around when there. It could be a bit tricky doing this as it’s not only a long way but there will be ever increasing ice to negotiate on the way north.”
Last week a University of Delaware researcher confirmed that an “ice island” four times the size of Manhattan broke off from the Petermann Glacier. The last time the Arctic lost such a large chunk of ice was in 1962.
“In the early morning hours of August 5, 2010, an ice island four times the size of Manhattan was born in northern Greenland,” said Andreas Muenchow, associate professor of physical ocean science and engineering at the University of Delaware's College of Earth, Ocean, and Environment. Muenchow's research in Nares Strait, between Greenland and Canada, is supported by the National Science Foundation (NSF).
Satellite imagery of this remote area at 81 degrees N latitude and 61 degrees W longitude, about 620 miles [1,000 km] south of the North Pole, reveals that Petermann Glacier lost about one-quarter of its 43-mile long [70 km] floating ice-shelf.
Trudy Wohlleben of the Canadian Ice Service discovered the ice island within hours after NASA's MODIS-Aqua satellite took the data on Aug. 5, at 8:40 UTC (4:40 EDT), Muenchow said. These raw data were downloaded, processed, and analyzed at the University of Delaware in near real-time as part of Muenchow's NSF research.
Petermann Glacier, the parent of the new ice island, is one of the two largest remaining glaciers in Greenland that terminate in floating shelves. The glacier connects the great Greenland ice sheet directly with the ocean.
The new ice island has an area of at least 100 square miles and a thickness up to half the height of the Empire State Building.
“The freshwater stored in this ice island could keep the Delaware or Hudson rivers flowing for more than two years. It could also keep all U.S. public tap water flowing for 120 days,” Muenchow said.
The last time such a massive ice island formed was in 1962 when Ward Hunt Ice Shelf calved a 230 square-mile island, smaller pieces of which became lodged between real islands inside Nares Strait. Petermann Glacier spawned smaller ice islands in 2001 (34 square miles) and 2008 (10 square miles). In 2005, the Ayles Ice Shelf disintegrated and became an ice island (34 square miles) about 60 miles to the west of Petermann Fjord.
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