Antarctic
Melting May Be Speeding Up
By Michael Byrnes
26 March, 2007
Reuters
HOBART (Australia)
- Rising sea levels and melting polar ice-sheets are at upper
limits of projections, leaving some human population centers already
unable to cope, top world scientists say as they analyze latest satellite
data.
A United Nations report by
the Intergovernmental Panel on Climate Change (IPCC) in February projected
sea level gains of 18-59 centimeters (7-23 inches) this century from
temperature rises of 1.8-4.0 Celsius (3.2-7.8 Farenheit).
“Observations are in
the very upper edge of the projections,” leading Australian marine
scientist John Church told Reuters.
“I feel that we’re
getting uncomfortably close to threshold,” said Church, of Australia’s
CSIRO Marine and Atmospheric Research said.
Past this level, parts of
the Antarctic and Greenland would approach a virtually irreversible
melting that would produce sea level rises of meters, he said.
There has been no repeat
in the Antarctic of the 2002 break-up of part of the Larsen ice shelf
that created a 500 billion ton iceberg as big as Luxembourg.
But the Antarctic Peninsula
is warming faster than anywhere else on Earth, and glaciers are in massive
retreat.
“There have been doomsday
scenarios that west Antarctica could collapse quite quickly. And there’s
six meters of sea level in west Antarctica,” says Tas van Ommen,
a glaciologist at the Hobart-based Australian Antarctic Division.
Doomsday has not yet arrived.
But even in east Antarctica,
which is insulated from global warming by extreme cold temperatures
and high-altitudes, new information shows the height of the Tottenham
Glacier near Australia’s Casey Base has fallen by 10 meters over
15-16 years.
MELTING POLES
Scientists say massive glacier
retreat at Heard Island, 1,000 km (620 miles) north of Antarctica, is
an example of how fringe areas of the polar region are melting.
The break-up of ice in Antarctica
to create icebergs is also opening pathways for accelerated flows to
the sea by glaciers.
Church pointed out that sea
levels were 4-6 meters higher more than 100,000 years ago when temperatures
were at levels expected to be reached at the end of this century.
Dynamic ice-flows could add
25 percent to IPCC forecasts of sea level rise, van Ommen said.
Australian scientist John
Hunter, who has focused on historical sea level information, said that
to keep the sea water out, communities would need to begin raising sea
walls.
“There’s lots
of places where you can’t do that and where you’ll have
to put up with actual flooding,” he said.
This was already happening
in the south of England, where local councils and governments could
not afford to protect all areas from sea water erosion as land continued
to sink.
About 100 million people
around the world live within a meter of the present-day sea level, CSIRO
Marine Research senior principal research scientist Steve Rintoul said.
“Those 100 million people will need to go somewhere,” he
said.
Worse, every meter of sea
level rise causes an inland recession of around 100 meters (300 feet)
and more erosion occurs with every storm.
“You can’t just
say we’ll just put sea walls,” Hunter said.
Copyright ©2007 Reuters
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