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Climate sensitivity on geological timescales controlled by nonlinear feedbacks and ocean circulation

Climate sensitivity on geological timescales controlled by nonlinear feedbacks and ocean circulation
Climate sensitivity on geological timescales controlled by nonlinear feedbacks and ocean circulation

Climate sensitivity is a key metric used to assess the magnitude of global warming given increased CO2 concentrations. The geological past can provide insights into climate sensitivity; however, on timescales of millions of years, factors other than CO2 can drive climate, including paleogeographic forcing and solar luminosity. Here, through an ensemble of climate model simulations covering the period 150–35 million years ago, we show that climate sensitivity to CO2 doubling varies between ∼3.5 and 5.5 °C through this time. These variations can be explained as a nonlinear response to solar luminosity, evolving surface albedo due to changes in ocean area, and changes in ocean circulation. The work shows that the modern climate sensitivity is relatively low in the context of the geological record, as a result of relatively weak feedbacks due to a relatively low CO2 baseline, and the presence of ice and relatively small ocean area in the modern continental configuration.

climate sensitivity, paleoclimate modeling
0094-8276
9880-9889
Farnsworth, A.
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Lunt, D.J.
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O'Brien, C.L.
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Foster, G.L.
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Inglis, G.N.
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Markwick, P.
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Pancost, R.D.
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Robinson, S.A.
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Farnsworth, A.
2be2b60e-d93a-4e07-bcf9-0147ad328e7a
Lunt, D.J.
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O'Brien, C.L.
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Foster, G.L.
fbaa7255-7267-4443-a55e-e2a791213022
Inglis, G.N.
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Markwick, P.
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Pancost, R.D.
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Robinson, S.A.
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Farnsworth, A., Lunt, D.J., O'Brien, C.L., Foster, G.L., Inglis, G.N., Markwick, P., Pancost, R.D. and Robinson, S.A. (2019) Climate sensitivity on geological timescales controlled by nonlinear feedbacks and ocean circulation. Geophysical Research Letters, 46 (16), 9880-9889. (doi:10.1029/2019GL083574).

Record type: Article

Abstract

Climate sensitivity is a key metric used to assess the magnitude of global warming given increased CO2 concentrations. The geological past can provide insights into climate sensitivity; however, on timescales of millions of years, factors other than CO2 can drive climate, including paleogeographic forcing and solar luminosity. Here, through an ensemble of climate model simulations covering the period 150–35 million years ago, we show that climate sensitivity to CO2 doubling varies between ∼3.5 and 5.5 °C through this time. These variations can be explained as a nonlinear response to solar luminosity, evolving surface albedo due to changes in ocean area, and changes in ocean circulation. The work shows that the modern climate sensitivity is relatively low in the context of the geological record, as a result of relatively weak feedbacks due to a relatively low CO2 baseline, and the presence of ice and relatively small ocean area in the modern continental configuration.

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More information

Accepted/In Press date: 9 July 2019
e-pub ahead of print date: 29 July 2019
Published date: 28 August 2019
Keywords: climate sensitivity, paleoclimate modeling

Identifiers

Local EPrints ID: 435413
URI: http://eprints.soton.ac.uk/id/eprint/435413
ISSN: 0094-8276
PURE UUID: 301de1c4-af16-4263-b9ba-ed297189701c
ORCID for G.L. Foster: ORCID iD orcid.org/0000-0003-3688-9668

Catalogue record

Date deposited: 06 Nov 2019 17:30
Last modified: 26 Nov 2021 05:03

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Contributors

Author: A. Farnsworth
Author: D.J. Lunt
Author: C.L. O'Brien
Author: G.L. Foster ORCID iD
Author: G.N. Inglis
Author: P. Markwick
Author: R.D. Pancost
Author: S.A. Robinson

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