Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum
Authors/Creators
- 1. Max Planck Institute for Chemistry
- 2. University of Southampton
- 3. Princeton University
- 4. Yale University
- 5. University of Ferrara
- 6. University of Milan
- 7. University of California Los Angeles
- 8. The Open University
- 9. Scripps Institution of Oceanography
- 10. University of California, Santa Cruz
Description
The global ocean's oxygen (O2) inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We present new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analogue to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM.
Notes
Funding provided by: National Science Foundation
Crossref Funder Registry ID: https://ror.org/021nxhr62
Award Number: EAR-2121466
Funding provided by: Max Planck Institute for Chemistry
Crossref Funder Registry ID: https://ror.org/02f5b7n18
Award Number:
Funding provided by: Princeton University
Crossref Funder Registry ID: https://ror.org/00hx57361
Award Number:
Methods
Moretti_et_al_2023_DataS1.csv
Fossil foraminifera were manually separated from the sediment fraction above 150 micrometres. Nitrogen isotope composition of organic linings encased in planktic foraminifera calcite (FB-δ15N) was measured with the persulfate-denitrifier method. Acid dissolution of foraminifera shells and potassium persulfate oxydation of organic linings were performed according to the methodology of Ren et al., 2009, with the subsequent modifications outlined in Leichliter et al., 2021. Analysis of FB-δ15N was performed through the denitrifier method and measured in an IRMS MAT253 coupled with a customized gas-bench (Sigman et al., 2001; Weigand et al., 2016).
Moretti_et_al_2023_DataS2.csv
Seawater pO2 is reconstructed by applying a trait-based physiological model for the response of foraminifera shell size to changes in temperature and oxygen. For our computations, we used published planktic and benthic foraminifera size records (Petrizzo et al., 2007; Kaiho et al., 2006) and reconstructed sea surface temperatures (Zachos et al., 2003). See "Related works".
Files
Moretti_et_al_2023_DataS1.csv
Additional details
Related works
- Is cited by
- 10.1016/j.palaeo.2005.12.017 (DOI)