calves island 4 times the size of Manhattan, UD scientist reports
1:40 p.m., Aug. 6, 2010----A
University of Delaware researcher reports that an "ice island" four times
the size of Manhattan has calved from Greenland's Petermann Glacier. The last
time the Arctic lost such a large chunk of ice was in 1962.
Satellite image from Aug. 5, 2010, shows the huge ice island
calved from Greenland's Petermann Glacier. Courtesy of Prof. Andreas Muenchow,
University of Delaware
"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).
Andreas Muenchow, UD associate professor of physical ocean
science and engineering
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 island will enter Nares Strait, a deep
waterway between northern Greenland and Canada where, since 2003, a University
of Delaware ocean and ice observing array has been maintained by Muenchow with
collaborators in Oregon (Prof. Kelly Falkner), British Columbia (Prof. Humfrey
Melling), and England (Prof. Helen Johnson).
"In Nares Strait, the ice island will encounter
real islands that are all much smaller in size," Muenchow said. "The newly
born ice-island may become land-fast, block the channel, or it may break into
smaller pieces as it is propelled south by the prevailing ocean currents. From
there, it will likely follow along the coasts of Baffin Island and Labrador, to
reach the Atlantic within the next two years."
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.
Credit University of Delaware