Ocean Carbon Release May Have Ended the Last Ice Age

What ended the last Ice Age? Apparently, carbon released from the oceans had something to do with it. Scientists have found that a release of CO2 from the deep ocean helped bring an end to the last Ice Age.

Atmospheric CO2 levels fluctuate from about 185 parts-per-million (ppm) during ice ages to around 280 ppm during warmer periods, like today. Currently, the oceans contain about sixty times more carbon than the atmosphere, and that carbon can actually exchange rapidly between the atmosphere and the ocean.

"The magnitude and rapidity of the swings in atmospheric CO2 across the ice age cycles suggests that changes in ocean carbon storage are important drivers of natural atmospheric CO2 variations," said Miguel Martinez-Boti, one of the researchers, in a news release.

In order to better understand the exchange between the two system, the researchers turned to the past. They studied the composition of the calcium carbonate shells of ancient marine organisms that inhabited the surface of the ocean thousands of years ago. This allowed them to trace the carbon content of the oceans.

The new data confirms that natural variations in atmospheric CO2 between ice ages and warm interglacials were driven largely by changes in the amount of carbon stored in the oceans. Not only that, but the findings show that there were rapid swings in atmospheric CO2 across the ice age cycles, which suggests that ocean carbon storage is an important driver of natural atmospheric CO2 variations.

"These results will help to better understanding the dynamics of human-induced CO2 accumulation in the atmosphere since the ocean is an important carbon sink and the largest reservoir of carbon on our planet," said Patrizia Ziveri, co-author of the new study.

The findings are published in the journal Nature.

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