NYT -- Large Ice Shelf in Antarctica Disintegrates at Great Speed
[Turn off those over-heating GPRS handsets !]
March 20, 2002
Large Ice Shelf in Antarctica Disintegrates at Great Speed
By ANDREW C. REVKIN
A Rhode Island-size piece of the floating
ice fringe along a fast-warming region
of Antarctica has disintegrated with
extraordinary rapidity, scientists said
yesterday.
The loss of floating ice does not contribute to
rising sea levels, just as melting ice cubes
floating in a glass do not cause it to overflow.
But the researchers said this was the first time
in thousands of years that this part of
Antarctica — the east coast of its arm-shaped
peninsula — had seen so much ice erode and
temperatures rise so much.
While it is too soon to say whether the changes
there are related to a buildup of the
"greenhouse" gas emissions that scientists
believe are warming the planet, many experts
said it was getting harder to find any other
explanation.
"With the disappearance of ice shelves that
have existed for thousands of years, you rather
rapidly run out of other explanations," said Dr.
Theodore A. Scambos, a glaciologist at the
National Snow and Ice Data Center at the
University of Colorado, which has been
monitoring the loss of ice in the Antarctic
along with the British Antarctic Survey.
Other parts of Antarctica have experienced
different trends, including a cooling of the
continent's interior in recent decades.
The latest ice breakup occurred in the Larsen B
ice shelf, which has probably existed since the
last ice age. "There's no evidence of any period
in the last 12,000 years where there was open
water in the area that has now been exposed,"
Dr. Scambos said.
For years, researchers hiking on the ice and
using satellites have been watching pieces of
the shelf slowly break away, but the
disintegration over the last month was on a
vastly greater scale, several experts said. "The
speed of it is staggering," said Dr. David
Vaughan, a glaciologist at the British Antarctic
Survey.
Starting in February, satellites recorded the
event as the ice sheet fragmented into
thousands of floes.
Scientists say the likely culprit is rapidly
warming summer air temperatures. Along that
part of the peninsula, temperatures have risen
4.5 degrees in five decades, and hundreds of
small ponds of meltwater have formed on the
surface of the Larsen shelf and others nearby.
The surface water migrates into tiny cracks in
the ice, steadily deepening and widening them
until the monumental structure starts to fall apart, Dr. Scambos said.
Copyright 2002 The New York Times Company |
