by Greg Roberts
April 18, 2009
ICE is expanding in much of
Antarctica, contrary to the widespread public
belief that global warming is melting the continental ice cap.
The results of ice-core drilling and sea ice monitoring indicate
there is no large-scale melting of ice over most of Antarctica,
although experts are concerned at ice losses on the continent's
Cool down... ice is
expanding in much of the Antarctic, experts say
Antarctica has 90 per cent of the
Earth's ice and 80 per cent of its fresh water, The Australian
reports. Extensive melting of Antarctic ice sheets would be required
to raise sea levels substantially, and ice is melting in parts of
west Antarctica. The destabilization of the Wilkins ice shelf
generated international headlines this month.
However, the picture is very different in east Antarctica, which
includes the territory claimed by Australia.
East Antarctica is four times the size of west Antarctica and parts
of it are cooling. The Scientific Committee on Antarctic Research
report prepared for last week's meeting of Antarctic Treaty nations
in Washington noted the South Pole had shown "significant cooling in
Australian Antarctic Division glaciology program head Ian
Allison said sea ice losses in west Antarctica over the past 30
years had been more than offset by increases in the Ross Sea region,
just one sector of east Antarctica.
"Sea ice conditions have remained
stable in Antarctica generally," Dr Allison said.
The melting of sea ice - fast ice and
pack ice - does not cause sea levels to rise because the ice is in
the water. Sea levels may rise with losses from freshwater ice
sheets on the polar caps. In Antarctica, these losses are in the
form of icebergs calved from ice shelves formed by glacial movements
on the mainland.
Last week, federal Environment Minister Peter Garrett said
experts predicted sea level rises of up to 6m from Antarctic melting
by 2100, but the worst case scenario foreshadowed by the SCAR report
was a 1.25m rise.
Mr Garrett insisted global warming was causing ice losses throughout
Antarctica. "I don't think there's any doubt it is contributing to
what we've seen both on the Wilkins shelf and more generally in
Antarctica," he said.
Dr Allison said there was not any evidence of significant change in
the mass of ice shelves in east Antarctica nor any indication that
its ice cap was melting.
"The only significant calvings in
Antarctica have been in the west," he said. And he cautioned
that calvings of the magnitude seen recently in west Antarctica
might not be unusual.
"Ice shelves in general have episodic carvings and there can be
large icebergs breaking off - I'm talking 100km or 200km long -
every 10 or 20 or 50 years."
Ice core drilling in the fast ice off
Australia's Davis Station in East Antarctica by the Antarctic
Climate and Ecosystems Co-Operative Research Centre shows that
last year, the ice had a maximum thickness of 1.89m, its densest in
The average thickness of the ice at
Davis since the 1950s is 1.67m.
A paper to be published soon by the British Antarctic Survey
in the journal Geophysical Research Letters is expected to
confirm that over the past 30 years, the area of sea ice around the
continent has expanded.
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