Ocean Carbon Storage across the middle Miocene: a new interpretation for the Monterey Event.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31919344.
- Also identified by DOI 10.1038/s41467-019-13792-0 and PMC identifier 6952451.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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<sup>13</sup>C) excursion, with oceans more depleted in <sup>12</sup>C relative to <sup>13</sup>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<sub>2</sub> as a cause for the subsequent Miocene Climate Transition and Antarctic glaciation. However, this hypothesis cannot explain the multi-Myr lag between the δ<sup>13</sup>C excursion and global cooling. We use planktic foraminiferal B/Ca, δ<sup>11</sup>B, δ<sup>13</sup>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.