The University of Southampton
University of Southampton Institutional Repository

Controls on the spatial distribution of oceanic δ13CDIC

Controls on the spatial distribution of oceanic δ13CDIC
Controls on the spatial distribution of oceanic δ13CDIC
We describe the design and evaluation of a large ensemble of coupled climate–carbon cycle simulations with the Earth system model of intermediate complexity GENIE. This ensemble has been designed for application to a range of carbon cycle questions, including the causes of late Quaternary fluctuations in atmospheric CO2. Here we evaluate the ensemble by applying it to a transient experiment over the recent industrial era (1858 to 2008 AD). We employ singular vector decomposition and principal component emulation to investigate the spatial modes of ensemble variabilityof oceanic dissolved inorganic carbon (DIC) δ13C, considering both the spun-up pre-industrial state and the transient change. These analyses allow us to separate the natural (preindustrial) and anthropogenic controls on the δ13CDIC distribution. We apply the same dimensionally-reduced emulation techniques to consider the drivers of the spatial uncertainty in anthropogenic DIC. We show that the sources of uncertainty related to the uptake of anthropogenic δ13CDIC and DIC are quite distinct. Uncertainty in anthropogenic δ13C uptake is controlled by air–sea gas exchange, which explains 63 % of modelled variance. This mode of variability is largely absent from the ensemble variability in CO2 uptake, which is rather driven by uncertainties in thermocline ventilation rates. Although the need to account for air–sea gas exchange is well known, these results suggest that, to leading order, uncertainties in the ocean uptake of anthropogenic 13C and CO2 are governed by very different processes. This illustrates the difficulties in reconstructing one from the other, and furthermore highlights the need for careful targeting of both δ13CDIC and DIC observations to better constrain the ocean sink of anthropogenic CO2.
1726-4170
1815-1833
Holden, P.B.
f1c22c9f-15d7-43ac-94b0-209193723888
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Müller, S.A.
460e8328-e12a-404f-b672-c6b9fae8b98d
Oliver, K.I.C.
588b11c6-4d0c-4c59-94e2-255688474987
Death, R.M.
8e0fe8eb-b4cd-4926-9a2a-4332f1198ae7
Ridgwell, A.
fe462786-0ad9-440d-9c11-b1b2f72fb8be
Holden, P.B.
f1c22c9f-15d7-43ac-94b0-209193723888
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Müller, S.A.
460e8328-e12a-404f-b672-c6b9fae8b98d
Oliver, K.I.C.
588b11c6-4d0c-4c59-94e2-255688474987
Death, R.M.
8e0fe8eb-b4cd-4926-9a2a-4332f1198ae7
Ridgwell, A.
fe462786-0ad9-440d-9c11-b1b2f72fb8be

Holden, P.B., Edwards, N.R., Müller, S.A., Oliver, K.I.C., Death, R.M. and Ridgwell, A. (2013) Controls on the spatial distribution of oceanic δ13CDIC. Biogeosciences, 10 (3), 1815-1833. (doi:10.5194/bg-10-1815-2013).

Record type: Article

Abstract

We describe the design and evaluation of a large ensemble of coupled climate–carbon cycle simulations with the Earth system model of intermediate complexity GENIE. This ensemble has been designed for application to a range of carbon cycle questions, including the causes of late Quaternary fluctuations in atmospheric CO2. Here we evaluate the ensemble by applying it to a transient experiment over the recent industrial era (1858 to 2008 AD). We employ singular vector decomposition and principal component emulation to investigate the spatial modes of ensemble variabilityof oceanic dissolved inorganic carbon (DIC) δ13C, considering both the spun-up pre-industrial state and the transient change. These analyses allow us to separate the natural (preindustrial) and anthropogenic controls on the δ13CDIC distribution. We apply the same dimensionally-reduced emulation techniques to consider the drivers of the spatial uncertainty in anthropogenic DIC. We show that the sources of uncertainty related to the uptake of anthropogenic δ13CDIC and DIC are quite distinct. Uncertainty in anthropogenic δ13C uptake is controlled by air–sea gas exchange, which explains 63 % of modelled variance. This mode of variability is largely absent from the ensemble variability in CO2 uptake, which is rather driven by uncertainties in thermocline ventilation rates. Although the need to account for air–sea gas exchange is well known, these results suggest that, to leading order, uncertainties in the ocean uptake of anthropogenic 13C and CO2 are governed by very different processes. This illustrates the difficulties in reconstructing one from the other, and furthermore highlights the need for careful targeting of both δ13CDIC and DIC observations to better constrain the ocean sink of anthropogenic CO2.

Text
bg-10-1815-2013 - Version of Record
Available under License Creative Commons Attribution.
Download (7MB)

More information

Published date: 19 March 2013
Additional Information: © Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License.
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 369260
URI: http://eprints.soton.ac.uk/id/eprint/369260
ISSN: 1726-4170
PURE UUID: 95b5a990-b1ba-436b-afbb-11b08290f644

Catalogue record

Date deposited: 23 Sep 2014 09:29
Last modified: 08 Jan 2022 09:17

Export record

Altmetrics

Contributors

Author: P.B. Holden
Author: N.R. Edwards
Author: S.A. Müller
Author: K.I.C. Oliver
Author: R.M. Death
Author: A. Ridgwell

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 http://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.

×