December 1, 2009

Melting Antarctic Ice Likely To Cause Major Rise In Sea Levels

A major scientific report released on Tuesday showed that rapid ice loss in West Antarctica will likely contribute heavily to a projected sea level rise of up to 4.5 feet by 2100, AFP reported.

For years scientists believed that most of Antarctica's continent-sized ice sheet was highly resistant to global warming, and that the more vulnerable West Antarctic ice block would remain intact for thousands of years to come.

But according to the review by more than 100 experts on the Scientific Committee on Antarctic Research, studies now show a huge loss of ice mass, mainly as a result of warmer ocean temperatures.

The report claims that this new evidence suggests West Antarctica in particular will add "tens of centimeters" to the global ocean watermark, which is predicted to go up two to nine times higher than the IPCC forecast.

Based on past studies, even the relatively modest IPCC projection of a 7-23 inch increase by 2100 would render several island nations unlivable and wreak havoc in low-lying deltas home to hundreds of millions.

Meanwhile, global warming's impact on the region is set to intensify over the next century due to the successful effort to repair depletion of the ozone layer.

The report found that a hole in the ozone layer caused by the release of CFC (chlorofluorocarbon) gases has cooled temperatures and shielded most of Antarctica from global warming.

John Turner, head of climate research for the British Antarctic Survey and lead editor of the review, said the most astonishing evidence is the way that one man-made environmental impact -- the ozone hole -- has shielded most of Antarctica from another, global warming.

But some climate skeptics contend that the stable temperatures -- and in some areas additional cooling -- over much of the vast Antarctic continent during the last 30 years is evidence that global warming trends were exaggerated or simply false.

But by century's end, experts say measures to control the CFC gases should "heal" the hole in around 50 to 60 years, leading to additional warming of about 5.4 Fahrenheit.

Over the last few decades, 90 percent of the Antarctic Peninsula's glaciers have retreated, though the bulk of the continent's ice sheet has so far shown little change.

* Earth's most powerful ocean current, the Antarctic Circumpolar Current, has warmed faster than the global ocean as a whole, which could likely disrupt the region's ecosystems, including the rise of alien species that compete with and replace native Antarctic inhabitants.

This rapid warming has resulted in the expansion of plant, animal and microbial communities -- many of them introduced by humans -- on newly thawed land in the Antarctic Peninsula.

* Sea ice loss and ocean acidification are directly affecting wildlife, and could reduce Antarctica's rich biodiversity, from the bottom to the top of the food chain.

Tiny krill have declined significantly, and in some areas Adelie penguin populations have dropped due to reduced sea ice and prey. But in other regions, notably Ross Sea and East Antarctica, penguin populations have remained stable or gone up.

* Carbon dioxide and methane levels are higher and increasing faster than at any time in the last 800,000 years. At the same time, recent studies show that small changes in climate over the last 11,000 years -- the last ice age -- has caused rapid ice loss along with shifts in ocean and atmospheric circulation.

Around 30,000 tourists a year visit Antarctica, some setting foot on outlying parts of the peninsula.

Julian Gutt, a researcher at Alfred Wegener Institute, said this increased human traffic, plus the warming on land and sea, are going to change the region's ecology -- allowing organisms to enter and survive that were previously excluded through climate or simple geography.


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