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
[ Dramatic
picture of crack in the Larsen B ice shelf in Antarctica...
]
CAPTION:
"This photo released by Greenpeace shows a crack in the
Larsen B ice shelf in the Wedden sea, in Antarctica."
(AFP/EPA/File)
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.
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
###
