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A new study led by researchers at the Australian National University (ANU) provides a clearer picture of conditions during the last ice age, when global ice sheets were at their peak, and could even lead to better models for future ones. climatic projections.
The study demonstrates a new way to recreate ocean conditions in the Atlantic during the Last Glacial Maximum (LGM), about 20,000 years ago.
Lead author Dr. Jimin Yu says scientists have been trying to rebuild ocean circulation during this time period for decades, due to the clues it offers about past COtwo levels and changes in climate.
“The LGM was a time of much lower COtwo levels, lower global temperature and lower sea levels, “said Dr. Yu.
The researchers say that old ocean models cannot explain the recently published data on LGM, which means a change of thinking was needed.
Using marine sediments to rebuild the deep-water carbonate ion, which it traces reflecting the acidity of seawater, the group generated a unique map showing water conditions for the last glacial Atlantic.
This map reveals a new model of deep glacial circulation in the Atlantic.
“We found that the carbon-rich deep waters of the Pacific extended north to about 20 ° S in the South Atlantic at a depth of three to four kilometers during the Last Glacial Maximum,” said Dr. Yu.
“This may have contributed critically to the decrease in atmospheric COtwo, thus helping to start the glacial maximum. “
According to Dr. Yu, ocean circulation is a key regulator of climate, storing and transporting heat, carbon and nutrients.
“This study suggests that when the waters changed during the LGM, carbon was stored in the deep ocean, reducing atmospheric COtwo levels, “said Dr. Yu.
This information could also help improve or test the performance of various climate models.
“If a model is capable of reproducing the data, a method known as back projection or backtesting could give us confidence in the model’s ability to map future weather conditions,” said Dr. Yu.
The research has been published in Nature Geoscience.
Earth’s glacial cycles enhanced by Antarctic sea ice
J. Yu et al. Last decrease in glacial atmospheric CO2 due to widespread expansion of the deep waters of the Pacific, Nature Geoscience (2020). DOI: 10.1038 / s41561-020-0610-5
Provided by the Australian National University
Citation: Historic carbon dioxide decline could contain clues to future climate (2020, July 24) retrieved on July 24, 2020 from https://phys.org/news/2020-07-historic-carbon-dioxide- decline-clues.html
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