Ocean Carbon Storage across the middle Miocene: a new interpretation for the Monterey Event

Abstract The Miocene Climatic Optimum (MCO, 14–17 Ma) was ~3–4 °C warmer than present, similar to estimates for 2100. Coincident with the MCO is the Monterey positive carbon isotope (δ 13 C) excursion, with oceans more depleted in 12 C relative to 13 C than any time in the past 50 Myrs. The long-sta...

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Bibliographic Details
Published in:Nature Communications
Main Authors: Sosdian, S. M., Babila, T. L., Greenop, R., Foster, G. L., Lear, C. H.
Format: Article in Journal/Newspaper
Language:English
Published: Springer Science and Business Media LLC 2020
Subjects:
General Physics and Astronomy
General Biochemistry, Genetics and Molecular Biology
General Chemistry
Antarctic
Antarc*
Online Access:http://dx.doi.org/10.1038/s41467-019-13792-0
http://www.nature.com/articles/s41467-019-13792-0.pdf
http://www.nature.com/articles/s41467-019-13792-0
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Summary:Abstract The Miocene Climatic Optimum (MCO, 14–17 Ma) was ~3–4 °C warmer than present, similar to estimates for 2100. Coincident with the MCO is the Monterey positive carbon isotope (δ 13 C) excursion, with oceans more depleted in 12 C relative to 13 C than any time in the past 50 Myrs. The long-standing Monterey Hypothesis uses this excursion to invoke massive marine organic carbon burial and draw-down of atmospheric CO 2 as a cause for the subsequent Miocene Climate Transition and Antarctic glaciation. However, this hypothesis cannot explain the multi-Myr lag between the δ 13 C excursion and global cooling. We use planktic foraminiferal B/Ca, δ 11 B, δ 13 C, and Mg/Ca to reconstruct surface ocean carbonate chemistry and temperature. We propose that the MCO was associated with elevated oceanic dissolved inorganic carbon caused by volcanic degassing, global warming, and sea-level rise. A key negative feedback of this warm climate was the organic carbon burial on drowned continental shelves.

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