IrishTimes

An iceberg twice the size of Manhattan broke free from Greenland’s massive Petermann Glacier, which could speed up the march of ice into northern waters, scientists said today.

This is the second time in less than two years that the Petermann Glacier has calved a monstrous ice island. In 2010, it unleashed another massive ice chunk into the sea.

The latest break was observed by Nasa’s Aqua satellite, which passes over the North Pole several times a day, and was noted by Trudy Wohlleben of the Canadian Ice Service.

“At this time of year, we’re always watching the Petermann Glacier,” Ms Wohlleben said, because it can spawn big icebergs that invade north Atlantic shipping lanes or imperil oil platforms in the Grand Banks off Newfoundland.

A large piece of the 2010 iceberg did just that, but caused no damage, she said. Nasa images showed the iceberg calving – breaking off from a floating river of ice called an ice tongue, part of the land-anchored Petermann Glacier – and moving downstream along a fjord on Greenland’s northwest coast. A rift in the ice had been identified in 2001, but on Monday a crack was evident.

On Tuesday, the satellite showed a bigger gap between the glacier and the iceberg, and the ice chunks further downstream were breaking up, Nasa said online.

“The floating extension (of the glacier) is breaking apart,” Eric Rignot of Nasa’s Jet Propulsion Laboratory said in a statement. “It is not a collapse, but it is certainly a significant event.”

One difference between the 2010 event is that this times the ice island broke off further upstream, where the ice was right up against the fjord’s rocky side walls, effectively damming the glacier’s seaward movement.

“This piece that has been much further back, may have actually been providing more of a frictional force to cork (the glacier) up than the piece that broke off in 2010, which was much further out,” said Andreas Muenchow, an Arctic oceanographer at the University of Delaware.

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