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

Weber, ME; Ellis, B; Thomas, ZA; Montenari, M; Cage, A; Harris, MRP; Jones, R; Power, A; Love, J; Young, J; Weyrich, LS; Cooper, A; Fogwill, C; Turney, CSM; Menviel, L; Baker, A; Golledge, NR; Etheridge, DM; Rubino, M; Thornton, DP; Mackintosh, A; Pike, J; Hall, IR; Bagshaw, EA; Rainsley, E; Bronk Ramsey, C; van Ommen, TD; Moy, AD; Curran, MAJ; Davies, S; Bird, MI; Munksgaard, NC; Rootes, CM; Millman, H; Vohra, J; Rivera, A

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ME Weber

B Ellis

ZA Thomas

MRP Harris

R Jones

A Power

J Love

J Young

LS Weyrich

A Cooper

C Fogwill

CSM Turney

L Menviel

A Baker

NR Golledge

DM Etheridge

M Rubino

DP Thornton

A Mackintosh

J Pike

IR Hall

EA Bagshaw

E Rainsley

C Bronk Ramsey

TD van Ommen

AD Moy

MAJ Curran

S Davies

MI Bird

NC Munksgaard

CM Rootes

H Millman

J Vohra

A Rivera


The Southern Ocean occupies some 14% of the planet’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, remineralisation 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 rise 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 significant regional marine carbon sink, which contributed to the plateau in CO2 at the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrates the need to incorporate such feedbacks into climate-carbon models.

Acceptance Date May 1, 2020
Publication Date Jul 1, 2020
Journal Nature Geoscience
Print ISSN 1752-0894
Publisher Nature Publishing Group
Pages 489-497
Keywords Climate change; Climate sciences; Cryospheric science; Palaeoceanography; Palaeoclimate
Publisher URL


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