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Updated: Dec 9, 2025

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses
Published on: October 21, 2016
The seawater carbon inventory at the Paleocene-Eocene Thermal Maximum
Laura L Haynes1,2, Bärbel Hönisch3,2
1Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027; lhaynes@vassar.edu.
Abstract:
The Paleocene-Eocene Thermal Maximum (PETM) (55.6 Mya) was a geologically rapid carbon-release event that is considered the closest natural analog to anthropogenic CO2 emissions. Recent work has used boron-based proxies in planktic foraminifera to characterize the extent of surface-ocean acidification that occurred during the event. However, seawater acidity alone provides an incomplete constraint on the nature and source of carbon release. Here, we apply previously undescribed culture calibrations for the B/Ca proxy in planktic foraminifera and use them to calculate relative changes in seawater-dissolved inorganic carbon (DIC) concentration, surmising that Pacific surface-ocean DIC increased by [Formula: see text] µmol/kg during the peak-PETM. Making reasonable assumptions for the pre-PETM oceanic DIC inventory, we provide a fully data-driven estimate of the PETM carbon source. Our reconstruction yields a mean source carbon δ13C of -10‰ and a mean increase in the oceanic C inventory of +14,900 petagrams of carbon (PgC), pointing to volcanic CO2 emissions as the main carbon source responsible for PETM warming.
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