Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum

Simone Moretti, Alexandra Auderset, Curtis Deutsch, Ronja Schmitz, Lukas Gerber, Ellen Thomas, Valeria Luciani, Maria Rose Petrizzo, Ralf Schiebel, Aradhna Tripati, Philip Sexton, Richard Norris, Roberta D’Onofrio, James Zachos, Daniel M. Sigman, Gerald H. Haug, Alfredo Martínez-García

Research output: Contribution to journalArticlepeer-review


The global ocean’s oxygen inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We report new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analog 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.

Original languageEnglish (US)
Pages (from-to)727-731
Number of pages5
Issue number6684
StatePublished - Feb 16 2024

All Science Journal Classification (ASJC) codes

  • General


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