[Vision2020] Giant ice island breaks off Greenland

[Saundra Lund]

http://www.msnbc.msn.com/id/38600087/ns/technology_and_science-science/

Giant ice island breaks off Greenland
Floating ice sheet is four times the size of Manhattan, scientists say

OurAmazingPlanet 
updated 8/6/2010 7:05:36 PM ET

A giant ice island has broken off the Petermann Glacier in northern
Greenland. 

The last time the Arctic lost such a large chunk of ice was in 1962. 

"In the early morning hours of Aug. 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. 

Satellite imagery of this remote area at 81 degrees north latitude and 61
degrees west longitude, about 620 miles south of the North Pole, reveals
that Petermann Glacier lost about one-quarter of its 43-mile-long 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.

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, which is 1,454 feet from
the ground to the top of its lightning rod.

"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, British Columbia, and England. 

"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. 

In July, a chunk of ice the size of Manhattan fell off of Greenland's
Jakobshavn Isbrae glacier.