THE PETERMANN Glacier grinds and slides toward the sea, terminating in a giant floating ice tongue, in this third in a series of three images taken by NASA's Aqua satellite along the northwestern coast of Greenland on 16th July.Like other glaciers that end in the ocean, Petermann periodically calves icebergs. A massive iceberg broke off in 2010 and now an ice island twice the size of Manhattan has broken free.
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 on Wednesday.
- 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.
- "At this time of year we're always watching the Petermann Glacier," noted by Trudy Wohlleben of the Canadian Ice Service, 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.
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 spied a bigger gap between the glacier and the iceberg, and the ice chunks further downstream were breaking up. "The floating extension (of the glacier) is breaking apart," NASA's Jet Propulsion Laboratory reported. "It is not a collapse but it is certainly a significant event."
- One difference between the 2010 event and this one is that the present 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.
- The 2010 break accelerated the Petermann Glacier's movement toward the sea by 10% to 20%, Muenchow said. The current break could have a greater effect on the glacier's movement.
Coastal glaciers like this floating ice tongue tend to block the ice flow headed for the sea. When ice chunks break loose, the land-based glaciers behind them often move more quickly, Muenchow said. The accelerated movement of the Petermann Glacier after the 2010 break was "noticeable but not dramatic".Muenchow said climate change was a factor in the current state of the Petermann Glacier. He said this glacier is as far back toward the land as it has been since the start of the Industrial Revolution more than 150 years ago.
Post a Comment