Alarming ice loss in Antarctica
2008-01-15 10:00
Washington - Antarctica lost billions of
tons of ice over the last decade, contributing to the rising
seas around the world, a climate researcher said on Monday.
The ice melted from two particular parts of the southern
continent, according to Eric Rignot and colleagues, who wrote
about the phenomenon in the journal Nature Geoscience.
Using satellites to monitor most of Antarctica's coastline,
the scientists estimate that West Antarctica lost 132 billion
tons of ice in 2006, compared to about 83 billion tons in
1996. The Antarctic Peninsula, which stretches toward South
America, lost about 60 billion tons in 2006.
To put this in perspective, four billion tons of ice would
be enough to provide drinking water to the more than 60 million
people of the United Kingdom for a year, fellow author Jonathan
Bamber of the University of Bristol said.
This ice loss is not from the so-called ice sheets that
cover the water around the continent. This melting occurred in
the glaciers that cover much of the Antarctic land mass, and
when that melts, it contributes to sea level rise in a way that
sea ice does not.
"One immediate consequence (of the melting Antarctic ice)
is to raise sea level," Rignot, of the Jet Propulsion
Laboratory, said. Antarctica's
contribution to global sea level rise was about 0.5mm in 2006, compared to about 0.3mm in 1996.
Rignot noted that the UN Intergovernmental Panel on
Climate Change figured Antarctica would not contribute at all
to sea level rise, and in fact predicted a growth of the big
ice sheet that covers much of the continent from enhanced
precipitation.
This prediction was supposed to come from increased
evaporation from the oceans as the planet warmed up, but this
has not been observed so far in Antarctica, Rignot said.
"In some regions the ice sheet is close to warm sources of
water. ... The parts of Antarctica we are seeing change right
now are closest to these heat sources," he said.
These findings are in line with what is happening to the
Greenland ice sheet, which melted at a record rate last year,
and with studies of Arctic sea ice, which ebbed to its lowest
level ever measured in 2007.
A study last week by researchers at the University of
Colorado at Boulder found that older, thicker Arctic sea ice
that lasts from year to year is giving way to younger, thinner
sea ice that is more susceptible to melting.
- Reuters