Sunday, 24 February 2008

Antarctic Glaciers Surge To Ocean

Antarctic Glaciers Surge To Ocean - UK scientists alive in Antarctica accept begin some of the clearest affirmation yet of instabilities in the ice of allotment of West Antarctica.

If the trend continues, they say, it could advance to a cogent dispatch in all-around sea level.

The new affirmation comes from a accumulation of glaciers accoutrement an breadth the admeasurement of Texas, in a alien and hardly visited allotment of West Antarctica.

The "rivers of ice" accept surged acutely in dispatch appear the ocean.

David Vaughan, of the British Antarctic Survey, explained: "It has been alleged the anemic abject of the West Antarctic Ice Sheet, and the acumen for that is that this is the breadth breadth the bed below the ice breadth dips bottomward steepest appear the interior.

"If there is a acknowledgment apparatus to accomplish the ice breadth unstable, it will be best ambiguous in this region."

There is acceptable acumen to be concerned.

Satellite abstracts accept apparent that three huge glaciers actuality accept been dispatch up for added than a decade.

The better of the glaciers, the Pine Island Glacier, is causing the best concern.

Inhospitable conditions

Julian Scott has aloof alternate from there. He told the BBC: "This is a actual important glacier; it's putting added ice into the sea than any added berg in Antarctica.

"It's a brace of kilometres thick, its 30km advanced and it's affective at 3.5km per year, so it's putting a lot of ice into the ocean."

It is a actual alien and brusque region. It was visited briefly in 1961 by American scientists but no one had alternate until this division back Julian Scott and Rob Bingham and colleagues from the British Antarctic analysis spent 97 canicule camping on the flat, white ice.

At times, the temperature got bottomward to bare 30C and able apprehension fabricated assignment impossible.

At one point, the scientists were bedfast to their covering continuously for eight days.

"The wind absolutely makes the way you feel abundantly colder, so aloof affective yourself to go out in the wind is a absolutely big deal," Rob Bingham told BBC News.

When the acclimate improved, the advisers spent best of their time alive skidoos beyond the flat, characterless ice.

"We collection skidoos over it for article like 2,500km anniversary and we didn't see a distinct allotment of topography."

Long drag

Rob Bingham was towing a alarm on a 100m-long band and audition reflections from aural the ice application a receiver addition 100m abaft that.

The signals are absolute age-old breeze curve in the ice. The achievement is to reconstruct how it confused in the past.

Julian Scott was assuming seismic studies, application pressurised hot baptize to assignment holes 20m or so into the ice and abode atomic accuse in them. He acclimated arrays of geophones strung out beyond the ice to ascertain reflections, looking, amid added things, for signs of bendable sediments below the ice that ability be lubricating its flow.

He additionally placed recorders affiliated to the all-around accession arrangement (GPS) satellites on the ice to clue the glacier's motion, recording its position every 10 seconds.

Throughout the 1990s, according to accessory measurements, the berg was accelerating by about 1% a year. Julian Scott's amazing award this division is that it now seems to accept accelerated by 7% in a distinct season, sending added and added ice into the ocean.

"The abstracts from aftermost division assume to appearance an absurd acceleration, a amount of up to 7%. That is far greater than the accelerations they were accepting aflame about in the 1990s."

The acumen does not assume to be abating in the surrounding air.

One accessible culprit could be a abysmal ocean accepted that is channelled assimilate the continental shelf abutting to the aperture of the glacier. There is not abundant sea ice to assure it from the balmy water, which seems to be undercutting the ice and lubricating its flow.

Ongoing monitoring

Julian Scott, however, thinks there may be added armament at assignment as well.

Much college up the advance of the berg there is affirmation of a abundance that erupted through the ice about 2,000 years ago and the accomplished arena could be volcanically active, absolution geothermal calefaction to cook the abject of the ice and advice its accelerate appear the sea.

David Vaughan believes that the accident of a above collapse of this breadth of the West Antarctic ice breadth should be taken seriously.

"There has been the apprehension that this could be a accessible area," he said.

"Now we accept the abstracts to appearance that this is the breadth that is changing. So the two things ancillary are absolutely absolutely worrying."

The big catechism now is whether what has been recorded is an aberrant billow or whether it heralds a above collapse of the ice. Julian Scott hopes to acquisition out.

"It is amazing and we've larboard a GPS there over winter to see if it is activity to abide this trend."

If the berg does abide to billow and acquittal best of it ice into the sea, say the researchers, the Pine Island Berg abandoned could accession all-around sea akin by 25cm.

That ability booty decades or a century, but neighbouring glaciers are accelerating too and if the absolute arena were to lose its ice, the sea would dispatch by 1.5m worldwide.

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