Ice Falling From Antarctic Shelf

BERLIN (AP) - Massive ice chunks are crumbling away from a shelf
in the western Antarctic Peninsula, researchers said Wednesday,
warning that 1,300 square miles of ice - an area larger than Rhode
Island - was in danger of breaking off in coming weeks.

The Wilkins Ice Shelf had been stable for most of the last
century, but began retreating in the 1990s. Researchers believe it
was held in place by an ice bridge linking Charcot Island to the
Antarctic mainland.

But the 127-square-mile (330-square-kilometer) bridge lost two
large chunks last year and then shattered completely on April 5.

"As a consequence of the collapse, the rifts, which had already
featured along the northern ice front, widened and new cracks
formed as the ice adjusted," the European Space Agency said in a
statement Wednesday on its Web site, citing new satellite images.

The first icebergs broke away on Friday, and since then some 270
square miles (700 square kilometers) of ice have dropped into the
sea, according to the satellite data.

"There is little doubt that these changes are the result of
atmospheric warming," said David Vaughan of the British Antarctic
Survey.

The falling away of Antarctic ice shelves does not, in itself,
raise sea levels, since the ice was already floating in the sea.
But such coastal tables of ice usually hold back glaciers, and when
they disintegrate that land ice will often flow more quickly into
the sea, contributing to sea-level rise.

Researchers said the quality and frequency of the ESA satellite
images have allowed them to analyze the Wilkins shelf breakup far
more effectively than any previous event.

"For the first time, I think, we can really begin to see the
processes that have brought about the demise of the ice shelf,"
Vaughan said.

He said eight ice shelves along the Antarctic Peninsula have
shown signs of retreat over the last few decades.

"The retreat of Wilkins Ice Shelf is the latest and the largest
of its kind," he said.

The Wilkins shelf, which is the size of Jamaica, lost 14 percent
of its mass last year, according to scientists who are looking at
whether global warming is the cause of its breakup.

Average temperatures in the Antarctic Peninsula have risen by
3.8 degrees Fahrenheit (2.5 Celsius) over the past 50 years -
higher than the average global rise, according to studies.

Over the next several weeks, scientists estimate the Wilkins
shelf will lose some 1,300 square miles (3,370 square kilometers) -
a piece larger than the state of Rhode Island, or two-thirds the
size of Luxembourg.

One researcher said, however, that it was unclear how the
situation would evolve.

"We are not sure if a new stable ice front will now form
between Latady Island, Petrie Ice Rises and Dorsey Island," said
Angelika Humbert of Germany's Muenster University Institute of
Geophysics.

But even more ice could break off "if the connection to Latady
Island is lost," she said, "though we have no indication that
this will happen in the near future."
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On the Net:
ESA's 'Webcam' from Space:
http://www.esa.int/esaEO/SEMWZS5DHNF-index-0.html


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