The University of Southampton
University of Southampton Institutional Repository

Global carbon cycle perturbation across the Eocene-Oligocene climate transition

Global carbon cycle perturbation across the Eocene-Oligocene climate transition
Global carbon cycle perturbation across the Eocene-Oligocene climate transition
The Eocene-Oligocene transition (EOT), ~34?Ma, marks a tipping point in the long-term Cenozoic greenhouse to icehouse climate transition. Paleorecords reveal stepwise rapid cooling and ice growth across the EOT tightly coupled to a transient benthic ?13C excursion and a major and permanent deepening of the carbonate compensation depth (CCD). Based on biogeochemical box modeling, Merico et al. (2008) suggested that a combination of (1) glacioeustatic sea level fall-induced shelf-basin carbonate burial fractionation and (2) shelf carbonate weathering can account for the carbon cycle perturbation, but this finding has been questioned. Alternative proposed mechanisms include increased ocean ventilation, decreased carbonate burial, increased organic carbon burial, increased silicate weathering, and increased ocean calcium concentration. Here we use an improved version of the biogeochemical box model of Merico et al. (2008) to reevaluate these competing hypotheses and an additional mechanism, the expansion of “carbon capacitors” such as permafrost and peatlands. We find that changes in calcium concentration, silicate weathering, and carbonate or organic carbon burial each yield a response that is fundamentally at odds with the form and/or sign of the paleorecords. Shelf-basin carbonate burial fractionation (CCD change), plus shelf carbonate weathering, sequestration of 12C-enriched carbon into carbon capacitors, and possibly increased ocean ventilation (?13C excursion), offers the best fit to the paleorecords. Further work is needed to understand why the EOT carbon cycle perturbation is so unique when the forcing mechanisms hypothesized to be responsible (cooling and ice growth) are not peculiar to this event.
Eocene-Oligocene transition, Cenozoic cooling, Antarctic glaciation, permafrost, carbonate shelf-basin fractionation, carbon cycle
0883-8305
311-329
Armstrong Mckay, David
9e7fc75d-311e-4980-9911-288d965a9e56
Tyrrell, Toby
6808411d-c9cf-47a3-88b6-c7c294f2d114
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Armstrong Mckay, David
9e7fc75d-311e-4980-9911-288d965a9e56
Tyrrell, Toby
6808411d-c9cf-47a3-88b6-c7c294f2d114
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6

Armstrong Mckay, David, Tyrrell, Toby and Wilson, Paul A. (2016) Global carbon cycle perturbation across the Eocene-Oligocene climate transition. Paleoceanography, 31 (2), 311-329. (doi:10.1002/2015PA002818).

Record type: Article

Abstract

The Eocene-Oligocene transition (EOT), ~34?Ma, marks a tipping point in the long-term Cenozoic greenhouse to icehouse climate transition. Paleorecords reveal stepwise rapid cooling and ice growth across the EOT tightly coupled to a transient benthic ?13C excursion and a major and permanent deepening of the carbonate compensation depth (CCD). Based on biogeochemical box modeling, Merico et al. (2008) suggested that a combination of (1) glacioeustatic sea level fall-induced shelf-basin carbonate burial fractionation and (2) shelf carbonate weathering can account for the carbon cycle perturbation, but this finding has been questioned. Alternative proposed mechanisms include increased ocean ventilation, decreased carbonate burial, increased organic carbon burial, increased silicate weathering, and increased ocean calcium concentration. Here we use an improved version of the biogeochemical box model of Merico et al. (2008) to reevaluate these competing hypotheses and an additional mechanism, the expansion of “carbon capacitors” such as permafrost and peatlands. We find that changes in calcium concentration, silicate weathering, and carbonate or organic carbon burial each yield a response that is fundamentally at odds with the form and/or sign of the paleorecords. Shelf-basin carbonate burial fractionation (CCD change), plus shelf carbonate weathering, sequestration of 12C-enriched carbon into carbon capacitors, and possibly increased ocean ventilation (?13C excursion), offers the best fit to the paleorecords. Further work is needed to understand why the EOT carbon cycle perturbation is so unique when the forcing mechanisms hypothesized to be responsible (cooling and ice growth) are not peculiar to this event.

Text
palo20297.pdf - Version of Record
Available under License Creative Commons Attribution.
Download (1MB)

More information

Published date: 20 February 2016
Keywords: Eocene-Oligocene transition, Cenozoic cooling, Antarctic glaciation, permafrost, carbonate shelf-basin fractionation, carbon cycle
Organisations: Ocean and Earth Science, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 388252
URI: https://eprints.soton.ac.uk/id/eprint/388252
ISSN: 0883-8305
PURE UUID: 825f9395-99dd-40cd-9677-99dc4f905028
ORCID for David Armstrong Mckay: ORCID iD orcid.org/0000-0002-0020-7461
ORCID for Toby Tyrrell: ORCID iD orcid.org/0000-0002-1002-1716

Catalogue record

Date deposited: 22 Feb 2016 14:55
Last modified: 06 Jun 2018 13:03

Export record

Altmetrics

Contributors

Author: David Armstrong Mckay ORCID iD
Author: Toby Tyrrell ORCID iD
Author: Paul A. Wilson

University divisions

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.

×