The University of Southampton
University of Southampton Institutional Repository

Enhanced carbon dioxide outgassing from the eastern equatorial Atlantic during the last glacial

Enhanced carbon dioxide outgassing from the eastern equatorial Atlantic during the last glacial
Enhanced carbon dioxide outgassing from the eastern equatorial Atlantic during the last glacial
Biological productivity and carbon export in the equatorial Atlantic are thought to have been dramatically higher during the last glacial period than during the Holocene. Here we reconstruct the pH and CO2 content of surface waters from the eastern equatorial Atlantic Ocean over the past ?30 k.y. using the boron isotope composition of Globigerinoides ruber (a mixed-layer–dwelling planktic foraminifera). Our new record, combined with previously published data, indicates that during the last glacial, in contrast to today, a strong west to east gradient existed in the extent of air:sea equilibrium with respect to pCO2 (?pCO2), with the eastern equatorial Atlantic acting as a significant source of CO2 (+100 ?atm) while the western Atlantic remained close to equilibrium (+25 ?atm). This pattern suggests that a fivefold increase in the upwelling rate of deeper waters drove increased Atlantic productivity and large-scale regional cooling during the last glacial, but the higher than modern ?pCO2 in the east indicates that export production did not keep up with enhanced upwelling of nutrients. However, the downstream decline of ?pCO2 provides evidence that the unused nutrients from the east were eventually used for biologic carbon export, thereby effectively negating the impact of changes in upwelling on atmospheric CO2 levels. Our findings indicate that the equatorial Atlantic exerted a minimal role in contributing to lower glacial-age atmospheric CO2.
0091-7613
1003-1006
Foster, G.L.
fbaa7255-7267-4443-a55e-e2a791213022
Sexton, P.F.
8f381c3d-6181-4027-bc35-258780a1f383
Foster, G.L.
fbaa7255-7267-4443-a55e-e2a791213022
Sexton, P.F.
8f381c3d-6181-4027-bc35-258780a1f383

Foster, G.L. and Sexton, P.F. (2014) Enhanced carbon dioxide outgassing from the eastern equatorial Atlantic during the last glacial. Geology, 42 (11), 1003-1006. (doi:10.1130/G35806.1).

Record type: Article

Abstract

Biological productivity and carbon export in the equatorial Atlantic are thought to have been dramatically higher during the last glacial period than during the Holocene. Here we reconstruct the pH and CO2 content of surface waters from the eastern equatorial Atlantic Ocean over the past ?30 k.y. using the boron isotope composition of Globigerinoides ruber (a mixed-layer–dwelling planktic foraminifera). Our new record, combined with previously published data, indicates that during the last glacial, in contrast to today, a strong west to east gradient existed in the extent of air:sea equilibrium with respect to pCO2 (?pCO2), with the eastern equatorial Atlantic acting as a significant source of CO2 (+100 ?atm) while the western Atlantic remained close to equilibrium (+25 ?atm). This pattern suggests that a fivefold increase in the upwelling rate of deeper waters drove increased Atlantic productivity and large-scale regional cooling during the last glacial, but the higher than modern ?pCO2 in the east indicates that export production did not keep up with enhanced upwelling of nutrients. However, the downstream decline of ?pCO2 provides evidence that the unused nutrients from the east were eventually used for biologic carbon export, thereby effectively negating the impact of changes in upwelling on atmospheric CO2 levels. Our findings indicate that the equatorial Atlantic exerted a minimal role in contributing to lower glacial-age atmospheric CO2.

PDF Geology-2014-Foster-G35806.1.pdf - Version of Record
Available under License Other.
Download (1MB)

More information

Published date: 7 October 2014
Organisations: Geochemistry

Identifiers

Local EPrints ID: 371668
URI: https://eprints.soton.ac.uk/id/eprint/371668
ISSN: 0091-7613
PURE UUID: 9d9bc29c-3b24-468b-8407-cbfab1c39491

Catalogue record

Date deposited: 11 Nov 2014 16:11
Last modified: 17 Jul 2017 21:47

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×