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Antarctic ice samples: What do they say about global warming?

Antarctic ice core samples, up to 150,000 years old, may help scientists estimate whether it will take 50 years - or 500 years - for the Ross Ice Shelf to collapse at the current rate of climate change.

Scientist Nancy Bertler holds the final section of ice she collected from a half-mile under Antarctica's surface in a laboratory freezer, near Wellington, New Zealand. Antarctica's pristine habitat provides a laboratory for scientists studying the effects of climate change.

(AP Photo/Nick Perry)

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Nancy Bertler and her team took a freezer to the coldest place on Earth, endured weeks of primitive living and risked spending the winter in Antarctic darkness, to go get ice — ice that records our climate's past and could point to its future.

They drilled out hundreds of ice cores, each slightly longer and wider than a baseball bat, from the half-mile-thick ice covering Antarctica's Roosevelt Island. The cores, which may total 150,000 years of snowfall, almost didn't survive the boat ride to New Zealand because of a power outage.

Bertler hopes the material will help her estimate how long the Ross Ice Shelf would last under the current rate of climate change before falling apart.

Evidence from the last core her team hauled out needs further study, but it contains material that Bertler said appeared to be marine sediment that formed recently — at least in geological terms measured in thousands of years.

That would bolster scientists' suspicions that the shelf could collapse again if global temperatures keep rising, triggering a chain of events that could raise sea levels around the world.

"From a scientific point of view, that's really exciting. From a personal point of view, that's really scary," said Bertler, a senior research fellow at the Antarctic Research Centre at the Victoria University of Wellington.

The ice shelf acts as a natural barrier protecting massive amounts of ice in West Antarctica, and that ice also could fall into the ocean if the shelf fell apart. Scientists say West Antarctica holds enough ice to raise sea levels by between 2 meters (6.5 feet) and 6 meters (20 feet) if significant parts of it were to collapse.


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