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Southern Ocean carbon sink enhanced by sea-ice feedbacks at the Antarctic Cold Reversal

journal contribution
posted on 2023-05-20, 15:29 authored by Fogwill, CJ, Turney, CSM, Menviel, L, Baker, A, Weber, ME, Ellis, B, Thomas, ZA, Golledge, NR, Etheridge, D, Rubino, M, Thornton, DP, Tasman van OmmenTasman van Ommen, Andrew MoyAndrew Moy, Mark Curran, Davies, S, Bird, MI, Munksgaard, NC, Rootes, CM, Millman, H, Vohra, J, Rivera, A, Macintosh, A, Pike, J, Hall, IR, Bagshaw, EA, Rainsley, E, Bronk-Ramsey, C, Montenari, M, Cage, AG, Harris, MRP, Jones, R, Power, A, Love, J, Young, J, Weyrich, LS, Cooper, A

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 CO2. 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 CO2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate–carbon models.

History

Publication title

Nature Geoscience

Volume

13

Pagination

489-497

ISSN

1752-0894

Department/School

Institute for Marine and Antarctic Studies

Publisher

Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2020 The Authors, under exclusive licence to Springer Nature Limited

Repository Status

  • Restricted

Socio-economic Objectives

Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)

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