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A change in the ocean circulation that helped to end the ice age



  A Shift in Ocean Circulation That Helped End the Ice Age
Credit: University of St Andrews

Changes in the North Pacific Circulation some 15,000 years ago have released large amounts of CO2 into the atmosphere, which has helped warm the planet and end the last Ice Age, according to research by University of St Andrews researchers.

The new study published today (April 23) in Nature Geoscience also found that the changes in circulation led to a reduction in the amount of oxygen in the deep sea. The results will help scientists understand the processes that control the exchange of CO2 and oxygen between the ocean and the atmosphere.

The researchers measured the chemical composition of the shells of tiny fossil plankton, foraminifera, which they used to reconstruct the exchange of CO2 between the North Pacific and the atmosphere at the end of the last Ice Age as the carbon dioxide level in the atmosphere increased. They found that the North Pacific released large amounts of CO2 into the atmosphere about 1

5,000 years ago, at a time when ocean currents in the Atlantic were rapidly changing. The results showed that the release of CO2 through the North Pacific was caused by a change in the circulation and could explain a decrease in the oxygen concentration in the Pacific, which was discovered more than 20 years ago. Scientists are observing a similar loss of oxygen from the ocean as the climate changes.

Lead author, dr. Will Gray from the School of Earth and Environmental Sciences at the University of St Andrews, formerly University College London, said: "Last week, we saw disturbing new studies that showed us that the ocean currents in the North Atlantic are slowing down we see very rapid changes in the North Pacific climate related to previous changes in ocean currents in the Atlantic. This gives us an example of how different parts of the climate system are interconnected, so that changes in the circulation in a region bring about changes in CO2 and oxygen the other side of the planet. "

DR. Gray added, "The North Pacific is very large and just below the water surface, the water bubbles with CO2, so we really need to understand how this region can change in the future, and a look into the past is a good way"

Co-author dr. James Rae, also from the University of St. Andrews, added: "Although the increase in CO2 caused by this process has been dramatically dramatic in geological terms, it has done so in comparison to modern ones. The CO2 increase in the atmosphere is so great like the CO2 increase that contributed to the end of the last ice age, but the man-made CO2 increase has been 100 times faster, which will have a huge impact on the climate system and one we are just beginning to see. "


Further information:
The last ice age

Further information:
William R. Gray et al. Deglazial upwelling, productivity and CO2 outgassing in the North Pacific Nature Geoscience (2018). DOI: 10.1038 / s41561-018-0108-6

Source:
Nature's geosciences

Provided by:
University of St Andrews


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