Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal
The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the...
Published in: | Nature Geoscience |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2020
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Subjects: | |
Online Access: | https://hdl.handle.net/1983/3c28095f-4def-4964-ae12-9d36a6966936 https://research-information.bris.ac.uk/en/publications/3c28095f-4def-4964-ae12-9d36a6966936 https://doi.org/10.1038/s41561-020-0587-0 http://www.scopus.com/inward/record.url?scp=85086786100&partnerID=8YFLogxK |
Summary: | The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, the role of these different processes in modulating past and future air–sea carbon flux remains poorly understood. A key period in this regard is the Antarctic Cold Reversal (ACR, 14.6–12.7 kyr bp), when mid- to high-latitude Southern Hemisphere cooling coincided with a sustained plateau in the global deglacial increase in atmospheric CO 2 . Here we reconstruct high-latitude Southern Ocean surface productivity from marine-derived aerosols captured in a highly resolved horizontal ice core. Our multiproxy reconstruction reveals a sustained signal of enhanced marine productivity across the ACR. Transient climate modelling indicates this period coincided with maximum seasonal variability in sea-ice extent, implying that sea-ice biological feedbacks enhanced CO 2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO 2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO 2 , and demonstrate the need to incorporate such feedbacks into climate–carbon models. |
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