05 Apr 2012:
End of Last Ice Age
Driven by Surge in CO2, Study Says
Large releases of carbon dioxide, primarily from oceans in the Southern Hemisphere, were the main factor in ending the last Ice Age
, according to a study that confirms the key role of CO2 in warming the planet. Researchers from Harvard and Oregon State University collected 80 samples from ice and sea sediment
cores to reconstruct CO2 and temperature levels as the last Ice Age ended beginning about 20,000 years ago. Previously, ice cores from Antarctica showed temperatures rising on that continent before
CO2 levels started to climb, leading global warming skeptics to contend that CO2 was not the main driver of warming. But the new study, published in Nature
, says that Antarctica was an anomaly and that the global ice and sediment cores unequivocally show that CO2 rose first, which then sparked temperature increases of 6 degrees F. The initial trigger to the end of the Ice Age was a change in the tilt of the Earth’s axis, which warmed land masses in the Northern Hemisphere and melted Arctic Ice, releasing huge amounts of cold, fresh water that changed global ocean circulation. That in turn warmed the Southern Hemisphere, which melted sea and terrestrial ice there, releasing CO2 trapped under the ocean and land, the study said. “This research points a strong finger at the idea that CO2 was a major player,” said co-author Jeremy Shakin of Harvard. He noted that CO2 levels have jumped roughly as much in the last century as they did during the 6,000-year period that ended the last Ice Age.
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