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Middle Eocene greenhouse warming facilitated by diminished weathering feedback

Middle Eocene greenhouse warming facilitated by diminished weathering feedback
Middle Eocene greenhouse warming facilitated by diminished weathering feedback

The Middle Eocene Climatic Optimum (MECO) represents a ~500-kyr period of global warming ~40 million years ago and is associated with a rise in atmospheric CO2 concentrations, but the cause of this CO2 rise remains enigmatic. Here we show, based on osmium isotope ratios (187Os/188Os) of marine sediments and published records of the carbonate compensation depth (CCD), that the continental silicate weathering response to the inferred CO2 rise and warming was strongly diminished during the MECO—in contrast to expectations from the silicate weathering thermostat hypothesis. We surmise that global early and middle Eocene warmth gradually diminished the weatherability of continental rocks and hence the strength of the silicate weathering feedback, allowing for the prolonged accumulation of volcanic CO2 in the oceans and atmosphere during the MECO. These results are supported by carbon cycle modeling simulations, which highlight the fundamental importance of a variable weathering feedback strength in climate and carbon cycle interactions in Earth’s history.

van der Ploeg, Robin
f17951c6-b5eb-479b-95a7-e04714635bb3
Selby, David
f97b6a1c-f11d-4819-bcdf-7d4a27bbd0ab
Cramwinckel, Margot J.
e467976c-be0c-47a5-a7eb-ecfe93048373
Li, Yang
a3af5ba3-2852-4f7c-ab48-9940e4da7646
Bohaty, Steven M.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Middelburg, Jack J.
abdca8a9-843f-4940-afe1-81c4df84b913
Sluijs, Appy
af623507-b795-4458-8ca5-cce783869a3d
van der Ploeg, Robin
f17951c6-b5eb-479b-95a7-e04714635bb3
Selby, David
f97b6a1c-f11d-4819-bcdf-7d4a27bbd0ab
Cramwinckel, Margot J.
e467976c-be0c-47a5-a7eb-ecfe93048373
Li, Yang
a3af5ba3-2852-4f7c-ab48-9940e4da7646
Bohaty, Steven M.
af9dbe78-8b9f-44f2-ba1d-20795837d2d1
Middelburg, Jack J.
abdca8a9-843f-4940-afe1-81c4df84b913
Sluijs, Appy
af623507-b795-4458-8ca5-cce783869a3d

van der Ploeg, Robin, Selby, David, Cramwinckel, Margot J., Li, Yang, Bohaty, Steven M., Middelburg, Jack J. and Sluijs, Appy (2018) Middle Eocene greenhouse warming facilitated by diminished weathering feedback. Nature Communications, 9 (1), [2877]. (doi:10.1038/s41467-018-05104-9).

Record type: Article

Abstract

The Middle Eocene Climatic Optimum (MECO) represents a ~500-kyr period of global warming ~40 million years ago and is associated with a rise in atmospheric CO2 concentrations, but the cause of this CO2 rise remains enigmatic. Here we show, based on osmium isotope ratios (187Os/188Os) of marine sediments and published records of the carbonate compensation depth (CCD), that the continental silicate weathering response to the inferred CO2 rise and warming was strongly diminished during the MECO—in contrast to expectations from the silicate weathering thermostat hypothesis. We surmise that global early and middle Eocene warmth gradually diminished the weatherability of continental rocks and hence the strength of the silicate weathering feedback, allowing for the prolonged accumulation of volcanic CO2 in the oceans and atmosphere during the MECO. These results are supported by carbon cycle modeling simulations, which highlight the fundamental importance of a variable weathering feedback strength in climate and carbon cycle interactions in Earth’s history.

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More information

Accepted/In Press date: 15 June 2018
e-pub ahead of print date: 23 July 2018
Published date: 1 December 2018

Identifiers

Local EPrints ID: 422929
URI: http://eprints.soton.ac.uk/id/eprint/422929
PURE UUID: 5f3bd7ab-0bda-43d4-850d-7b8c2cb90356
ORCID for Margot J. Cramwinckel: ORCID iD orcid.org/0000-0002-6063-836X
ORCID for Steven M. Bohaty: ORCID iD orcid.org/0000-0002-1193-7398

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Date deposited: 08 Aug 2018 16:30
Last modified: 06 Jun 2024 01:44

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Contributors

Author: Robin van der Ploeg
Author: David Selby
Author: Margot J. Cramwinckel ORCID iD
Author: Yang Li
Author: Jack J. Middelburg
Author: Appy Sluijs

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