Middle Eocene greenhouse warming facilitated by diminished weathering feedback

van der Ploeg, R.; Selby, D.; Cramwinckel, M.J.; Li, Y.; Bohaty, S.M.; Middelburg, J.J.; Sluijs, A.

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.

Citation

van der Ploeg, R., Selby, D., Cramwinckel, M., Li, Y., Bohaty, S., Middelburg, J., & Sluijs, A. (2018). Middle Eocene greenhouse warming facilitated by diminished weathering feedback. Nature Communications, 9, Article 2877. https://doi.org/10.1038/s41467-018-05104-9

• Journal Article Type: Article
• Acceptance Date: Jul 10, 2018
• Online Publication Date: Jul 23, 2018
• Publication Date: Jul 23, 2018
• Deposit Date: Jul 3, 2018
• Publicly Available Date: Jul 24, 2018
• Journal: Nature Communications
• Electronic ISSN: 2041-1723
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Article Number: 2877
• DOI: https://doi.org/10.1038/s41467-018-05104-9
• Public URL: https://durham-repository.worktribe.com/output/1327586