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Study shows Antarctic glaciers shrinking
(Agencies)
Updated: 2005-04-22 11:16
The first comprehensive survey of glaciers on the Antarctic peninsula has
shown that the rivers of ice are shrinking, mostly because of warming of the
local climate.
These aerial
pictures show the retreat of marine glaciers on the Antarctic peninsular.
An in-depth study using aerial photographs spanning the last half century
of all 244 marine glaciers on the west side of the Antarctic peninsular
found that 87% of them are in retreat and the speed is rising.
[Reuters] |
It is unclear, however, whether
the increased temperature causing the shrinkage is a natural regional effect or
a result of human-influenced global warming, said the scientists who conducted
the study, published this week in the journal Science.
Researchers from the British Antarctic Survey and the U.S. Geological Survey
analyzed more than 2,000 aerial photographs dating from 1940 and over 100
satellite images from the 1960s onwards.
They calculated that 87 percent of the 244 glaciers going out to sea from the
peninsula have retreated over the last 50 years and that the pace of shrinkage
has accelerated over the last decade. Until now, scientists were uncertain
whether the glaciers were growing or melting.
"Fifty years ago, most of the glaciers we look at were slowly growing in
length but since then this pattern has reversed. In the last five years the
majority were actually shrinking rapidly," said the study's leader, Alison Cook
of the British Antarctic Survey. "However, 32 glaciers go against the trend and
are showing minor advance. Had we not studied such a large number of glaciers we
may have missed the overall pattern."
The Antarctic peninsula is a small segment of the Antarctic continent,
located at the South Pole, and the behavior of the ice on the peninsula is not
necessarily a reflection of what's going on elsewhere in Antarctica, said
another of the investigators, David Vaughan of the British Antarctic Survey.
Temperatures seem to be much warmer there than on the rest of the continent.
Evidence from the main Antarctic ice sheet is mixed, with some areas of the
continent showing shrinkage and others showing thickening.
Ice shrinkage has also been documented in Alaska and the North Pole.
Scientists worry about the melting of the ice sheets because the extra water
may increase sea levels, which in turn could mean more flooding damage to
coastal areas during storms.
Sea levels have risen by 10 centimeters to 20 centimeters over the last 100
years and experts predict it could rise by a meter over the next 100 years.
However, the study was not able to tell whether the shrinkage is having a
meaningful impact on sea levels.
It is also unclear whether changes in the larger ice sheet in Antarctica are
contributing to sea level rise, Vaughan said.
"This is another piece in the jigsaw that tells us how climate change is
affecting the planet. It may not be a significant piece, but there's a
million-piece jigsaw out there to be filled in ... and this is one piece in it,"
Vaughan said.
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