ANTARCTIC THREAT TO SEA LEVEL
- ANTARCTIC THREAT TO SEA LEVEL
By Michael McCarthy
New Zealand Herald
February 3, 2005
British scientists have discovered a threat to the world that may be a
result of global warming.
An international conference on climate change has been told that a
massive Antarctic ice sheet, whose collapse would raise sea levels
around the world by more than 5m, and which has been assumed to be
stable, might be starting to disintegrate.
Researchers from the Cambridge-based British Antarctic Survey are
measuring remote points in the West Antarctic Ice Sheet where they
have recently found ice to be flowing out into the sea at the enormous
rate of 250cu km a year.
This discharge alone is raising global sea levels by a fifth of a
millimetre a year.
Professor Chris Rapley, the survey's director, told the conference at
the UK Meteorological Office in Exeter that their discovery had
reactivated worries about the ice sheet's collapse - which only four
years ago were firmly dismissed.
He said: "The last report [by the UN's Intergovernmental Panel on
Climate Change] characterised Antarctica as a slumbering giant in
terms of climate change.
"I would say that it is now an awakened giant. There is real concern."
He added: "The previous view was that the West Antarctic Ice Sheet
would not collapse before the year 2100. We now have to revise that
judgment. We cannot be so sanguine."
Collapse of the sheet would be a disaster for the whole world, putting
enormous swathes of low-lying, desperately poor countries such as
Bangladesh under water.
The conference has been called by British Prime Minister Tony Blair as
part of Britain's efforts to increase the pace of international action
on climate change.
Blair has asked it to explore the question of just how much climate
change the world can take, before the consequences are catastrophic
for human society and natural ecosystems.
It heard several alarming warnings of possible climate-related
catastrophic events, including the failure of the Gulf Stream, which
keeps the British Isles warm, and the melting of the ice sheet
But it was the revelations of Rapley, head of one of the world's most
respected scientific bodies, which were the most dramatic, as they
reopened a concern which many scientists assumed had been laid to rest.
Antarctica as a whole is land covered by very thick ice, but the ice
sheet covering the eastern half of the continent is very stable as it
sits on rocks which are well above sea level.
Worries about the ice covering the western half first surfaced more
than 25 years ago when it was realised that there, the base rocks are
actually well below the level of the sea.
In some circumstances, it was feared, such as a melting of the edge of
the ice sheet because of rising temperatures, sea water could get
under it and eventually lead to its collapse.
The dramatic discharge into the Amundsen Sea completely opened up the
whole debate, Rapley said.
It had only been recently discovered because the area was so remote. But
British scientists, with United States logistical help, had now
established a base in the area to investigate further.
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