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."
RIPPED....The
image of the Petermann Glacier in a series of three images taken by NASA's Aqua
satellite shows the glacier as it ripped apart before split.
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. (Reuters)
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