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Varied contribution of the Southern Ocean to deglacial atmospheric CO2 rise

Varied contribution of the Southern Ocean to deglacial atmospheric CO2 rise
Varied contribution of the Southern Ocean to deglacial atmospheric CO2 rise
Glacial–interglacial changes in atmospheric CO2 are generally attributed to changes in seawater carbon chemistry in response to large-scale shifts in the ocean’s biogeochemistry and general circulation. The Southern Ocean currently takes up more CO2than any other and it is likely to have played a crucial role in regulating past atmospheric CO2. However, the physical, biologi-cal and chemical variables that control ocean–atmosphere CO2 exchange during glacial–interglacial cycles are not completely understood. Here we use boron isotopes and carbon isotopes in planktonic foraminifera and an alkenone-based proxy of tem-perature to reconstruct the seawater pH and CO2 partial pressure in sub-Antarctic surface waters south of Tasmania over the past 25,000 years, and investigate the mechanisms that regulate seawater CO2. The new record shows that surface waters in this region were a sink for atmospheric CO2 during the Last Glacial Maximum. Our reconstruction suggests changes in the strength of the biological pump and the release of deep-ocean CO2 to surface waters contributed to the last deglacial rise in atmospheric CO2. These findings demonstrate that variations in upwelling intensity and the distribution of Southern Ocean water masses in this sector played a key role in regulating atmospheric CO2 during the last glacial–interglacial cycle.
1752-0894
1006-1011
Moy, Andrew
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Palmer, Martin
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Howard, William R
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Bijma, Jelle
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Cooper, Matthew
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Calvo, Eva
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Pelejero, Carles
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Gagan, Michael
472e495c-2e36-4311-8a00-3fffa06439c3
Chalk, Thomas
5f15ed08-5ec8-4029-ae73-d49c6ac4fd29
Moy, Andrew
a4ee2e3c-07f3-42fb-ae30-887528915d5c
Palmer, Martin
d2e60e81-5d6e-4ddb-a243-602537286080
Howard, William R
3e0f97ea-9e93-419c-b6fc-6d101de7cc7e
Bijma, Jelle
a95f461d-5b65-43f4-8aec-6a058ab0536a
Cooper, Matthew
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Calvo, Eva
f22e0607-53e9-491e-9553-461309dba124
Pelejero, Carles
355d6d26-4485-496b-8de0-f1f28729b061
Gagan, Michael
472e495c-2e36-4311-8a00-3fffa06439c3
Chalk, Thomas
5f15ed08-5ec8-4029-ae73-d49c6ac4fd29

Moy, Andrew, Palmer, Martin, Howard, William R, Bijma, Jelle, Cooper, Matthew, Calvo, Eva, Pelejero, Carles, Gagan, Michael and Chalk, Thomas (2019) Varied contribution of the Southern Ocean to deglacial atmospheric CO2 rise. Nature Geoscience, 12 (12), 1006-1011. (doi:10.1038/s41561-019-0473-9).

Record type: Article

Abstract

Glacial–interglacial changes in atmospheric CO2 are generally attributed to changes in seawater carbon chemistry in response to large-scale shifts in the ocean’s biogeochemistry and general circulation. The Southern Ocean currently takes up more CO2than any other and it is likely to have played a crucial role in regulating past atmospheric CO2. However, the physical, biologi-cal and chemical variables that control ocean–atmosphere CO2 exchange during glacial–interglacial cycles are not completely understood. Here we use boron isotopes and carbon isotopes in planktonic foraminifera and an alkenone-based proxy of tem-perature to reconstruct the seawater pH and CO2 partial pressure in sub-Antarctic surface waters south of Tasmania over the past 25,000 years, and investigate the mechanisms that regulate seawater CO2. The new record shows that surface waters in this region were a sink for atmospheric CO2 during the Last Glacial Maximum. Our reconstruction suggests changes in the strength of the biological pump and the release of deep-ocean CO2 to surface waters contributed to the last deglacial rise in atmospheric CO2. These findings demonstrate that variations in upwelling intensity and the distribution of Southern Ocean water masses in this sector played a key role in regulating atmospheric CO2 during the last glacial–interglacial cycle.

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Moy_et_al_final - Accepted Manuscript
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More information

Accepted/In Press date: 13 September 2019
e-pub ahead of print date: 21 October 2019
Published date: December 2019

Identifiers

Local EPrints ID: 435098
URI: http://eprints.soton.ac.uk/id/eprint/435098
ISSN: 1752-0894
PURE UUID: 1916eb47-3305-46a1-806f-718649ab8a0b
ORCID for Matthew Cooper: ORCID iD orcid.org/0000-0002-2130-2759

Catalogue record

Date deposited: 22 Oct 2019 16:30
Last modified: 26 Nov 2021 05:34

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Contributors

Author: Andrew Moy
Author: Martin Palmer
Author: William R Howard
Author: Jelle Bijma
Author: Matthew Cooper ORCID iD
Author: Eva Calvo
Author: Carles Pelejero
Author: Michael Gagan
Author: Thomas Chalk

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