November 01, 2003

Warm Seas Melting Ice Shelf the Size of Scotland

Independent (UK): An ice shelf in Antarctica the size of Scotland is rapidly disintegrating because of warmer seas, scientists said yesterday. They believe that the Larsen ice shelf on the Antarctic peninsula may disappear within 70 years.

http://www.commondreams.org/headlines03/1031-04.htm

Published on Friday, October 31, 2003 by the
lndependent/UK
Warm Seas Melting Ice Shelf the Size of Scotland
by Steve Connor

An ice shelf in Antarctica the size of Scotland is
rapidly disintegrating because of warmer seas,
scientists said yesterday. They believe that the
Larsen ice shelf on the Antarctic peninsula may
disappear within 70 years.

This photo released by Greenpeace shows a crack in the
Larsen B ice shelf in the Wedden sea, in Antarctica.
(AFP/EPA/File)

Although the ice shelf will not raise sea levels - it
is already floating on the ocean - scientists say that
its loss may trigger a release of ice from the
peninsula's mainland, causing global sea levels to
rise by 1 meter (3ft 3in).


Researchers led by Andrew Shepherd, a glaciologist
from Cambridge University, found that the Larsen ice
shelf had thinned by as much as 18 meters in the past
10 years. That can only be explained by a warmer
ocean, he said.

The study is published in the journal Science a day
after a study revealed that the ice in the Arctic was
melting rapidly due to a rise in temperatures,
threatening the natural habitat of the polar bear.

Both studies used radar measurements taken by the
European Space Agency's ERS-1 and ERS-2 satellites.
This enabled the scientists to monitor the loss of ice
over huge areas of sea at opposite ends of the Earth
for 10 years.

Dr Shepherd said: "We've discovered that the Larsen
ice shelf is thinning due to warmer oceans around it."

The radar measurements of the ice shelf's average
height above the sea, which are accurate to within
20cm, revealed a pattern of thinning since
measurements began in 1992, Dr Shepherd said.

The amount of melting freshwater running off the ice
shelf into the surrounding sea was equivalent to eight
times the flow of the river Thames. This could disturb
the local sea currents that were part of a much wider
global ocean circulation, he said. Dr Shepherd said
that it was not possible to say with certainty whether
global warming was directly responsible for the
melting. However, he said that it was indisputable
that the sea around the Antarctic peninsula was
getting warmer - although other parts of the Antarctic
continent were getting colder.

Dr Shepherd said the Larsen ice shelf was about 300
meters thick. When two previous sections of the shelf
thinned to about 200 meters they quickly
disintegrated.

Current estimates suggested that the Larsen ice shelf
would begin to disintegrate rapidly by about 2070,
although that was likely to happen sooner if current
warming trends continued, Dr Shepherd said.

The disappearance of the ice shelf might also affect
the local ice sheets, large bodies of ice trapped on
land by the ice shelf. "This is a really important
indicator of how grounded ice behind will respond to
this disintegration," Dr Shepherd said.

Much bigger ice shelves in Antarctica are also being
monitored. The Ronne and the Ross ice shelves are
about 10 times the size of the Larsen ice shelf and
their disintegration would be a far more serious
event. Scientists estimate that the Larsen ice shelf
has been in existence for 2,000 years and took many
centuries to form.


2003 Independent Digital (UK) Ltd

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Posted by richard at November 1, 2003 07:41 AM