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Sequestration of carbon in the deep Atlantic during the last glaciation

Sequestration of carbon in the deep Atlantic during the last glaciation
Sequestration of carbon in the deep Atlantic during the last glaciation
Atmospheric CO2 concentrations declined markedly about 70,000 years ago, when the Earth’s climate descended into the last glaciation. Much of the carbon removed from the atmosphere has been suspected to have entered the deep oceans, but evidence for increased carbon storage remains elusive. Here we use the B/Ca ratios of benthic foraminifera from several sites across the Atlantic Ocean to reconstruct changes in the carbonate ion concentration and hence the carbon inventory of the deep Atlantic across this transition. We find that deep Atlantic carbonate ion concentration declined by around 25??mol?kg?1 between ~80,000 and 65,000 years ago. This drop implies that the deep Atlantic carbon inventory increased by at least 50?Gt around the same time as the amount of atmospheric carbon dropped by about 60?Gt. From a comparison with proxy records of deep circulation and climate model simulations, we infer that the carbon sequestration coincided with a shoaling of the Atlantic meridional overturning circulation. We thus conclude that changes in the Atlantic Ocean circulation may have played an important role in reductions of atmospheric CO2 concentrations during the last glaciation, by increasing the carbon storage in the deep Atlantic.
1752-0894
319-324
Yu, J.
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Menviel, L.
7b589d2f-6bfe-47e7-8069-958c5056390b
Jin, Z.D.
72dff064-e84c-45b6-a784-79642ebf6b74
Thornalley, D.J.R.
3dade064-b9a0-4fe8-9cc0-e6d1850f691f
Barker, S.
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Marino, G.
d2f4dc29-b2e7-4cf0-8abd-6fd855bfab81
Rohling, E.J.
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Cai, Y.
0d30b3eb-8aeb-46e6-87ef-7fff9fded7a1
Zhang, F.
396ca776-f0e6-4750-974a-6ba3f9c78a41
Wang, X.
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Dai, Y.
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Chen, P.
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Broecker, W.S.
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Yu, J.
f0cc5bca-6305-4361-9b00-67975b8a1d2e
Menviel, L.
7b589d2f-6bfe-47e7-8069-958c5056390b
Jin, Z.D.
72dff064-e84c-45b6-a784-79642ebf6b74
Thornalley, D.J.R.
3dade064-b9a0-4fe8-9cc0-e6d1850f691f
Barker, S.
1639a15b-e369-4173-9f46-fc371f32cc3b
Marino, G.
d2f4dc29-b2e7-4cf0-8abd-6fd855bfab81
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Cai, Y.
0d30b3eb-8aeb-46e6-87ef-7fff9fded7a1
Zhang, F.
396ca776-f0e6-4750-974a-6ba3f9c78a41
Wang, X.
976221d1-3004-409c-8640-715bedfc5d15
Dai, Y.
e7363d2e-b07a-43ee-bcce-dd3bd95d3976
Chen, P.
9cb0bcb4-6fa8-4a1b-9f51-d0d95377053b
Broecker, W.S.
5c6a50b2-5056-4b9b-a5df-62e3b5a7929a

Yu, J., Menviel, L., Jin, Z.D., Thornalley, D.J.R., Barker, S., Marino, G., Rohling, E.J., Cai, Y., Zhang, F., Wang, X., Dai, Y., Chen, P. and Broecker, W.S. (2016) Sequestration of carbon in the deep Atlantic during the last glaciation. Nature Geoscience, 9, 319-324. (doi:10.1038/ngeo2657).

Record type: Article

Abstract

Atmospheric CO2 concentrations declined markedly about 70,000 years ago, when the Earth’s climate descended into the last glaciation. Much of the carbon removed from the atmosphere has been suspected to have entered the deep oceans, but evidence for increased carbon storage remains elusive. Here we use the B/Ca ratios of benthic foraminifera from several sites across the Atlantic Ocean to reconstruct changes in the carbonate ion concentration and hence the carbon inventory of the deep Atlantic across this transition. We find that deep Atlantic carbonate ion concentration declined by around 25??mol?kg?1 between ~80,000 and 65,000 years ago. This drop implies that the deep Atlantic carbon inventory increased by at least 50?Gt around the same time as the amount of atmospheric carbon dropped by about 60?Gt. From a comparison with proxy records of deep circulation and climate model simulations, we infer that the carbon sequestration coincided with a shoaling of the Atlantic meridional overturning circulation. We thus conclude that changes in the Atlantic Ocean circulation may have played an important role in reductions of atmospheric CO2 concentrations during the last glaciation, by increasing the carbon storage in the deep Atlantic.

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More information

e-pub ahead of print date: 8 February 2016
Published date: 16 February 2016
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 388221
URI: http://eprints.soton.ac.uk/id/eprint/388221
ISSN: 1752-0894
PURE UUID: 02b60a0f-9fb3-4583-a963-24d600061bb8
ORCID for E.J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 22 Feb 2016 11:50
Last modified: 15 Mar 2024 02:47

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Contributors

Author: J. Yu
Author: L. Menviel
Author: Z.D. Jin
Author: D.J.R. Thornalley
Author: S. Barker
Author: G. Marino
Author: E.J. Rohling ORCID iD
Author: Y. Cai
Author: F. Zhang
Author: X. Wang
Author: Y. Dai
Author: P. Chen
Author: W.S. Broecker

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