Antarctic ice formed at CO2 levels much higher than today's

Not going to melt any time soon, says boffin

New research has shown that the mighty ice sheet covering the Antarctic froze into being when the world had a much higher level of carbon dioxide in its atmosphere than it does today.

By analysing ancient algae found in deep-sea core samples, Professor Matthew Huber and his colleagues determined that the mile-thick ice which now covers the south polar continent formed around 34 million years ago. At that stage the atmosphere held much more CO2 than it does now, some 600 parts per million (ppm) as opposed to today's level of 390 ppm.

There is often concern that the Antarctic ice sheet might melt due to global warming (though in fact, despite much publicity over losses of ice from the Western peninsula, Antarctic ice has been steadily increasing in extent for the last 40 years). It would seem that this is highly unlikely given current and near-future levels of atmospheric CO2: at current rates of increase it will take a century at least to reach 600 ppm, the level at which the ice sheet formed itself, and higher levels would be needed to actually start it melting.

Even once the process begins there won't be any need for our great-grandchildren to panic, according to Huber.

"If we continue on our current path of warming we will eventually reach that tipping point," he says. "Of course after we cross that threshold it will still take many thousands of years to melt an ice sheet."

The new research is published in premier boffinry mag Science, here. ®

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