Antarctic ice sheet is an 'awakened giant'

[Guest guest]

while parts of the southern continent have been getting colder over the last

decade(something to do with wind changes), apparantly it isn't on all of the

land mass

a second thing to think about..all that ice sitting there is HEAVY

it actually presses the continent down...

if the ice all melts, the continent will actually rise....actually displacing

MORE water

whee!

 

http://www.newscientist.com/article.ns?id=dn6962

 

Antarctic ice sheet is an 'awakened giant'

13:38 02 February 2005

The massive west Antarctic ice sheet, previously assumed to be

stable, is starting to collapse, scientists warned on Tuesday.

 

Antarctica contains more than 90% of the world's ice, and the loss of

any significant part of it would cause a substantial sea level rise.

Scientists used to view Antarctica as a " slumbering giant " , said

Chris Rapley, from the British Antarctic Survey, but now he sees it

as an " awakened giant " .

 

Rapley presented measurements of the ice sheet at a major climate

conference in Exeter, UK. Glaciers on the Antarctic peninsula, which

protrudes from the continent to the north, were already known to be

retreating. But the data Rapley presented show that glaciers within

the much larger west Antarctic Ice sheet are also starting to

disappear.

 

If the ice on the peninsula melts entirely it will raise global sea

levels by 0.3 metres, and the west Antarctic ice sheet contains

enough water to contribute metres more. The last report of the

Intergovernmental Panel on Climate Change, published in 2001, said

that collapse of this ice sheet was unlikely during the 21st century.

That may now need to be reassessed, Rapley warned.

 

Cork from a bottle

Changes on the peninsula, where 75% of the 400 mountain glaciers are

in retreat, have provided new insights into the ways that ice sheets

may disintegrate.

 

In March 2002, a huge floating ice shelf known as Larsen B shattered

into icebergs. This turned out to have an effect akin to pulling a

cork from a bottle. With Larsen B no longer impeding movement, the

ice floes that fed the shelf began moving faster towards the sea and

started to thin. The finding took scientists by surprise when

revealed in September 2004 and now modellers are now working to

include such mechanisms in their predictions.

 

Climate records derived from the analysis of sediments show that ice

shelves off the peninsula have been absent in several earlier eras,

when natural variability warmed the world. But the break-up is

affecting ice closer to the pole than ever recorded, said

Rapley. " It's like the Heineken effect, " he said, referring to the

beer adverts that claim Heineken " reaches the parts other beers

cannot reach " .

 

Indications that climate change may be affecting the west Antarctic

ice sheet comes from three glaciers, including Pine Island and

Thwaites. Data reveal they are losing more ice - mainly through the

calving of icebergs - than is being replaced by snowfall. According

to a preliminary analysis, the difference between the mass lost and

mass replaced is about 60%.

 

Whether the loss of mass by the glaciers is due to natural variation

or is caused by human-influenced warming of the oceans is not known

for sure. Scientists are now making more field measurements to assess

the causes, but warming is a likely culprit, said Rapley: " The fact

that three of them are simultaneously accelerating suggests that is

the case. " The melting of these three glaciers alone is contributing

an estimated 0.24 millimetres per year to sea level.

 

 

 

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