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A glaciologist installs a pole as part of a satellite monitoring system into an ice shelf - Source: Reuters -
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Dismayed by ice and storms, British explorer Captain James Cook
had no regrets when he abandoned a voyage searching for a fabled
southern continent in 1773.
Finding only icebergs after he was the first to cross the Antarctic
Circle, he wrote ruefully that if anyone ventured further and found
a "land doomed by nature...to lie for ever buried under everlasting
ice and snow":
"I shall not envy him the honour of discovery, but I will be bold
to say that the world will not be benefited by it."
Things may be worse than he thought.
Climate change is turning Antarctica's ice into one of the biggest
risks for coming centuries. Even a tiny melt could drive up sea
levels, affecting cities from New York to Beijing, or nations from
Bangladesh to the Cook Islands - named after the mariner - in the
Pacific.
Scientists are now trying to design ever more high tech experiments
- with satellite radars, lasers, robot submarines, or even deep
drilling through perhaps three kilometres of ice - to plug huge
gaps in understanding the risks.
"If you're going to have even a few metres it will change the
geography of the planet," Rajendra Pachauri, head of the UN's
Intergovernmental Panel on Climate Change (IPCC), said of the more
extreme scenarios of fast ocean rise.
"Greenland and Antarctica are two huge bodies of ice sitting on
land that could really have very serious implications for the
levels of the seas," Pachauri said.
Eventually discovered in 1820, Antarctica locks up enough water to
raise sea levels by 57 metres.
Greenland stores the equivalent of seven metres.
Worries about sea level rise are among the drivers of 190-nation
talks on a new UN deal to combat climate change, mainly by a shift
away from fossil fuels, due to be agreed in Copenhagen in
December.
Collapse
Scientists are concentrating on the fringes, where the ice meets a
warming Southern Ocean.
"It's the underside of the ice sheets that's crucial," said
David Carlson, a scientist who headed the International Polar Year
from 2007-08.
Warmer seas may be thawing ice sheets around the edges, he said,
and allow ice to slide off the land into the sea more quickly,
adding water to sea levels.
But it is hard to be sure because of a lack of long-term
observations.
"The same things that defeated Cook - ice and bad weather - are
still problems," Carlson said.
About 10 ice shelves, extensions of ice sheets that float on the
ocean and can be hundreds of metres thick, have collapsed on the
Antarctic Peninsula in the past 50 years.
Part of the Wilkins Ice Shelf snapped in April.
And recent studies indicate a slight warming trend in Antarctica,
teased out from computer studies of temperature records.
Still, most of Antarctica is not going to thaw - the average
year-round temperature is -58.00F.
One possibility is to look far back into history.
Studies indicate that in the Eemian about 125,000 years ago, for
instance, temperatures were slightly higher than now,
hippopotamuses bathed in the Rhine - and seas were four metres
higher.
"We need to know where the extra four metres came from," said David
Vaughan, a glaciologist at the British Antarctic Survey (BAS),
adding that one possibility was that West Antarctica's ice had
collapsed.
He said that an operation to drill through ice - about three km
thick - to bedrock could help find out.
West Antarctica is vulnerable because its ice rests on rocks
below sea level and holds enough ice to raise sea levels by 3-6
metres.
A sample of rocks beneath the ice would reveal if and when they had
last been exposed to cosmic rays - which cause chemical changes
that can be read like a clock.
There could also be fossils or ancient sediments under the ice
to fix dates.
If the ice had collapsed in the Eemian or during other warm periods
between Ice Ages, it would set off global alarm bells about risks
of a fast rise in sea levels, Vaughan said.
A finding that the ice had been stable would be a huge
relief.
In early September, UN Secretary-General Ban Ki-moon said world sea
levels could rise by between 0.5 and two metres this century, far
higher than most experts have forecast.
Pachauri's IPCC spoke of a rise of 18-59 cms by 2100, excluding a
possible acceleration of a thaw of Antarctica or Greenland.
Seas rose 17 cms in the past century.
And another complicating issue is that experts have found lakes
under ice sheets in recent decades - but no one understands whether
they might lubricate the slide.
Lakes, such as Vostok where Russian scientists are close to
drilling through to the water entombed deep under the ice, might
even be a place where life has evolved in isolation.
Unknown types of life in Lake Vostok might hint at chances of life
in space, for instance on Jupiter's moon Europa - an icy ball which
might have liquid water near its warmer core.
Right or wrong?
"Was Cook right? Of course not. The Antarctic has been a treasure
trove of scientific information," Jane Lubchenco, head of the US
National Oceanic and Atmospheric Administration (NOAA), said.
She said the Antarctic Treaty, signed in 1959, had been a model for
world cooperation even during the Cold War between Moscow and
Washington.
Nations put territorial claims on hold and set the continent
aside for peace and science.
And the hole in the ozone layer - which shields the planet from
damaging ultra-violet rays - was discovered over Antarctica in the
1980s, adding to urgency of the 1987 Montreal Protocol to limit
emissions of ozone-damaging gases.
On a smaller scale, some whalers and seal hunters made their
fortunes in Antarctica after the first sighting of the continent in
1820 by Fabian von Bellingshausen, an Estonian captain in the
Russian navy.
In a reversal of Cook's assessment, glaciologist Vaughan said
Antarctica itself is getting no benefit from people.
"Until the beginning of the 20th century there were no human
footprints in Antarctica. Now the footprint of all humankind is
firmly on the entire continent because of climate change," he
said.
