The release of carbon dioxide from the oceans led to the ending of the Glacial Period, British and Australian scientists revealed in a recent study. The planet was heated by CO2 stored in deep oceans. Researchers from Australia’s National University (ANU), and England’s University of Southampton said that their research will provide scientists with a better understanding of how oceans impact climate change and carbon cycles. The study was published in Nature. Many parts of North America, Europe and the Arctic were permanently frozen during the last Ice Age. The Research School of Earth Sciences is part of ANU. Dr. Gianluca Martino said that the ocean contains 60 more carbon than its atmosphere. This makes it the primary driver of variations in carbon dioxide. The ocean can quickly exchange carbon dioxide with the atmosphere. Carbon dioxide levels have varied from 185 parts per million (parts/million) during the last Ice Age to 280ppm over other times in the past 1000 years. Since 1980,, carbon dioxide levels have nearly reached 400ppm. Ice melted over 9,000 years in last Ice Age North America and Scandinavia were once covered with over 50 million cubic kilometers of ice. It gradually melted away from about 19,000 to 10,000 years ago. The melting of enough water resulted in the sea level rising by 130 metres. The researchers looked at levels of boron in microfossils found on the ocean floor. This was used to reconstruct carbon dioxide levels from years ago. These levels were compared to the Co2 levels that had been previously recorded in Antarctic ice cores. They found that the levels of CO2 in the ocean after the last ice age was over, owing to the presence of tiny organisms at the South Atlantic Ocean or Eastern Equatorial Pacific’s surface, were significantly higher than the atmospheric level. Dr Miguel Martinez Boti was the joint-lead author. He stated that this suggests that the ocean is releasing carbon dioxide to the atmosphere. This was because the temperature was low during the Ice Age. When temperatures drop, the oceans have a weaker mix, which helps keep carbon in the ocean’s floor for many millennia. Researchers believe that other oceans could also play a role. They concluded that carbon from the Southern Ocean that was trapped in it surfaced at the end the previous Ice Age and was then released into the atmosphere. Gabin Foster (co-author) believes that other oceans, like the Pacific, could have contributed to a similar story. Foster stated that while our results suggest that the Southern Ocean plays a major role, we still don’t know all the details. New data shows that oceanic carbon dioxide leakage during the last deglaciation is linked to natural variations in atmospheric CO2. “Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation.” Nature 518, 219-222, (12 February 2015), doi: 10. 1038/nature14155.
