Sat, May 29, 2010 - Page 7 News List

Deep-sea carbon ‘burp’ helped end ice age: study

AFP , WASHINGTON

A giant “burp” of carbon dioxide stored under the ocean between South Africa and Antarctica may have helped end the last ice age more than 18,000 years ago, according to a new study.

The study, led by a scientist from Cambridge University, is “the first concrete evidence that carbon dioxide was more efficiently locked away in the deep ocean during the last ice age,” he said.

The team made its discovery by doing radiocarbon dating on shells under the Southern Ocean from tiny foraminifera creatures, says the study, which was due to be published in yesterday’s Science magazine.

Luke Skinner’s team measured carbon-14 levels in the shells and compared this with carbon levels in the atmosphere at the time, to work out how long the carbon dioxide had been locked in the ocean.

“Our results show that during the last ice age, around 20,000 years ago, carbon dioxide dissolved in the deep water circulating around Antarctica was locked away for much longer than today,” Skinner said.

This could clarify “how ocean mixing processes lock up more carbon dioxide during glacial periods,” he said.

According to the study, “pulses” or “burps” of carbon dioxide from the deep Southern Ocean helped trigger a global thaw every 100,000 years or so. The size of these pulses was roughly equivalent to the change in carbon dioxide experienced since the start of the industrial revolution.”

“If this theory is correct, we would expect to see large transfers of carbon from the ocean to the atmosphere at the end of each ice age,” Skinner said.

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