December 3, 2011

Decrease In CO2 Levels Linked To Polar Ice Sheet Formation

A drastic decrease in atmospheric carbon dioxide levels appears to have been the catalyst that led to the formation of the Antarctic ice sheet, according to a new study published December 1 in the journal Science.

The research, which was completed by an international team of experts led by Mark Pagani of Yale University, "helps solve a long-standing scientific puzzle and confirms the power of CO2 to dramatically alter global climate," according to a Thursday press release from the University of New South Wales (NSW), which participated in the project.

The study shows that atmospheric CO2 levels dropped by 40% both before and during of the formation of the polar ice sheet some 34 million years ago -- a period of approximately 3 million years, in all -- and "confirms that significant falls in the greenhouse gas result in global cooling, just as rises result in global warming," NSW officials added.

Pagani and colleagues were able to draw their conclusions by analyzing molecules obtained from ancient algae that had been found in deep-sea core samples.

"The key role of the greenhouse gas in one of the biggest climate events in Earth's history supports carbon dioxide's importance in past climate change and implicates it as a significant force in present and future climate," Purdue University, who also contributed to the research, said in a separate media advisory.

"The team pinpointed a threshold for low levels of carbon dioxide below which an ice sheet forms in the South Pole, but how much the greenhouse gas must increase before the ice sheet melts - which is the relevant question for the future - remains a mystery," they continued.

"The team found the tipping point in atmospheric carbon dioxide levels for cooling that initiates ice sheet formation is about 600 parts per million," the university press release concluded. "Prior to the levels dropping this low, it was too warm for the ice sheet to form."

Currently, the Earth's CO2 levels are at 390 parts per million, which is enough to maintain the ice sheet. However, increasing levels of the greenhouse gas and temperatures are both rising, with levels expected to reach levels of between 550 and 1,000 parts per million by the next century.


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