[Mb-civic] Dramatic change in West Antarctic ice could produce 16ft rise in sea levels

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Dramatic change in West Antarctic ice could produce 16ft rise in sea levels
By Michael McCarthy, Environment Editor
02 February 2005

Dramatic change in West Antarctic ice could produce 16ft rise in sea levels

Coral reefs may start to dissolve in 30 years

Leading article: Icy warningindependent portfolio

British scientists have discovered a new threat to the world which may be a
result of global warming. Researchers from the Cambridge-based British
Antarctic Survey (BAS) have discovered that a massive Antarctic ice sheet
previously assumed to be stable may be starting to disintegrate, a
conference on climate change heard yesterday. Its collapse would raise sea
levels around the earth by more than 16 feet.

BAS staff are carrying out urgent measurements of the remote points in the
West Antarctic Ice Sheet (WAIS) where they have found ice to be flowing into
the sea at the enormous rate of 250 cubic kilometres a year, a discharge
alone that is raising global sea levels by a fifth of a millimetre a year.

Professor Chris Rapley, the BAS director, told the conference at the UK
Meteorological Office in Exeter, which was attended by scientists from all
over the world, that their discovery had reactivated worries about the ice
sheet's collapse.

Only four years ago, in the last report of the UN's Intergovernmental Panel
on Climate Change (IPCC), worries that the ice sheet was disintegrating were
firmly dismissed.

Professor Rapley said: "The last IPCC report characterised Antarctica as a
slumbering giant in terms of climate change. I would say it is now an
awakened giant. There is real concern."

He added: "The previous view was that WAIS would not collapse before the
year 2100. We now have to revise that judgement. We cannot be so sanguine."
Collapse of the WAIS would be a disaster, putting enormous chunks of
low-lying, desperately poor countries such as Bangladesh under water - not
to mention much of southern England.

The conference has been called by Tony Blair as part of Britain's efforts to
increase the pace of international action on climate change, in a year when
the UK is heading the G8 group of industrialised nations and the European
Union.

Mr Blair has asked it to explore the question of how much climate change the
world can take before the consequences are catastrophic for human society
and ecosystems.

Yesterday, it heard several alarming new 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
covering Greenland.

But it was the revelations of Professor Rapley, head of one of the world's
most respected scientific bodies, which were the most dramatic, as they
reopened a concern many scientists assumed had been laid to rest.

Antarctica as a whole is a 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 that 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 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 from rising temperatures, sea water could get under it and
eventually lead to its collapse.

Yet the 2001 IPCC report, the principal consensus view of the international
community of climate scientists, thought that very unlikely, and said such a
collapse was improbable before the end of the current century, or even for
1,000 years.

What puts a very big question mark over this, Professor Rapley said, was the
recent discovery of the extremely rapid discharge of ice into the Amundsen
sea from the WAIS at three remote ice streams, Pine Island, Thwaites, and
another unnamed site.

"There is a very dramatic discharge from this region which, five years ago
when the IPCC report was written, we just didn't know about," he said. "What
we have found completely opens up the whole debate." It had only been
recently discovered, he said, because the area was so remote. But BAS
scientists, with US help, had established a base in the area to investigate.
Professor Rapley said there was some evidence that the discharge was a
relatively recent phenomenon and it might be caused by rising ocean
temperatures.

Margaret Beckett, the Environment Secretary, who opened the conference,
added another ominous prediction when she said that major global warming
impacts on the world in the next 20 to 30 years could not be avoided.
Whatever we do, potentially disastrous world temperature rises will take
place because they are already "built into the system," she said.

Her forecast that we are powerless to prevent major damage from climate
change is accepted by scientists but it is rare for such a frank admission
from a politician. It reflects the concern at a high level.

It was amplified by senior climate researchers, who said the amount of
future warming to which the world is firmly committed, because of greenhouse
gases that have already been put into the atmosphere, will be enough to
threaten the survival of many ecosystems and wildlife species such as polar
bears and penguins.

"I believe that most of the warming we are expecting over the next few
decades is now virtually inevitable, and even in this time frame we may
expect a significant impact," Mrs Beckett said.
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