[wordup] Antarctic ice shelf breaks apart

[Adam Shand]

Wow, lots of facinating stuff on /. today.

Via: http://slashdot.org/article.pl?sid=02/03/19/1245202
From: http://news.bbc.co.uk/hi/english/sci/tech/newsid_1880000/1880566.stm

Tuesday, 19 March, 2002, 06:25 GMT
Antarctic ice shelf breaks apart

An Antarctic ice shelf that was 200 metres thick and had a surface area
of 3,250 square kilometers has broken apart in less than two months.

UK scientists say the Larsen B shelf on the eastern side of the
Antarctic Peninsula has fragmented into small icebergs.

Researchers from the British Antarctic Survey (Bas) predicted in 1998
that several ice shelves around the peninsula were doomed because of
rising temperatures in the region - but the speed with which the Larsen
B has gone has shocked them.

"We knew what was left would collapse eventually, but the speed of it is
staggering," said Dr David Vaughan, a glaciologist at the Bas in
Cambridge.

"[It is hard] to believe that 500 billion tonnes of ice sheet has
disintegrated in less than a month."

Faster flow

The climate on the peninsula has changed rapidly in the last 50 years.
The region has experienced a 2.5-degree-Celsius rise in average
temperatures - an increase greater than for any location in the Southern
Hemisphere.

However, the picture generally in Antarctica is a complicated one with
temperatures in the interior actually falling over the same period.
There is also some evidence that the retreat of the West Antarctic Ice
Sheet, on the other side of the peninsula to the Larsen B shelf, has
halted.

The Larsen B was one of five ice shelves - huge masses of ice that are
floating extensions of the ice sheets covering the land - that had been
steadily shrinking because of climate change, Dr Vaughan said.

But the break up of the ice mass would not raise sea levels because the
ice was already floating, he added. Sea levels would only be affected if
the land ice behind it now began to flow more rapidly into the sea.

Gather data

The UK scientists were first alerted to the Larsen B collapse by US
colleagues studying images from the American space agency's Modis
satellite.

Ice, US National Snow And Ice Data Center
The area is now littered with small icebergs
The British Antarctic Survey then dispatched its research ship RRS James
Clark Ross to the area to obtain photographs and samples.

Scientists hope the data gathered on site will help them determine when
such an event last happened and which ice shelves are threatened in
future.

The US-based National Snow and Ice Data Center (NSIDC) said on Tuesday:
"This is the largest single event in a series of retreats by ice shelves
in the peninsula over the last 30 years.

"The retreats are attributed to a strong climate warming in the region."

Future predictions

"We know that the climate in this area has been relatively stable for at
least 1,800 years, but now it is starting to change," Dr Vaughan told
the BBC.

"Has it been kicked off by (human induced) global warming or is it
something a bit more natural?

"For glaciologists this is fascinating because we can see the processes
at work and we can predict with more certainty what is going to happen
in the rest of Antarctica.

"As far as global implications are concerned, there are few as far as
the present event is concerned."

Locally, however, Dr Vaughan said there would be ecological changes as
organisms moved into the seabed area no longer covered by ice.

Big berg

US scientists also reported on Tuesday that an iceberg more than nine
times larger than Singapore had broken off Antarctica.

B-22, US National Ice Center
This image of B-22 was taken on 11 March
The National Ice Center said the berg, named B-22, broke free from an
ice tongue in the Amundsen Sea, an area of Antarctica south of the
Pacific Ocean.

It is more than 64 kilometers (40 miles) wide and 85 kilometers (53
miles) long, and covers an area of about 5,500 square kilometers.

Icebergs are named for the section of Antarctica where they are first
sighted. The B designation covers the Amundsen and eastern Ross seas and
the 22 indicates it is the 22nd iceberg sighted there by the US National
Ice Center.