EGU24-17106, updated on 12 Jun 2024
https://doi.org/10.5194/egusphere-egu24-17106
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Is the ocean losing its breath? Insights into ocean oxygenation from Cenozoic warm periods.

Alexandra Auderset1,2, Anya Hess3, Simone Moretti2, Daniel Sigman4, and Alfredo Martínez-García2
Alexandra Auderset et al.
  • 1University of Southampton, Southampton, United Kingdom (a.auderset@soton.ac.uk)
  • 2Max Planck Institute for Chemistry, Mainz, Germany
  • 3Rutgers University, New Brunswick, NJ, USA
  • 4Princeton University, Princeton, NJ, USA

The continuous expansion of oxygen-deficient zones (ODZs) poses risks to marine ecosystems and societies dependent on fisheries for income and sustenance. However, the trajectory of this deoxygenation in response to 21st-century climate change remains uncertain. To gain a clearer understanding of future oxygen dynamics and processes leading to deoxygenation, we investigate the response of ODZs during Cenozoic global warming periods in the Miocene and Early Eocene, using a combination of oxygen-sensitive proxies including foraminifer-bound nitrogen isotopes (FB-δ15N) and iodine-to-calcium ratios in planktic foraminifer shells (I/Ca). Our findings reveal contracted, rather than expanded, tropical Pacific ODZs during all studied warm intervals. The increased oxygenation closely aligns with high-latitude warming and reduced meridional sea surface temperature gradients, indicating a climatic driver behind these observed changes. We discuss potential causes for the contraction of ODZs, including (i) diminished wind-driven equatorial upwelling and primary productivity, and/or (ii) increased deep-ocean ventilation. Finally, we compare the behaviour of Pacific vs. Indian Ocean ODZs during the Miocene and investigate potential teleconnections between these two wind-driven ODZs.

How to cite: Auderset, A., Hess, A., Moretti, S., Sigman, D., and Martínez-García, A.: Is the ocean losing its breath? Insights into ocean oxygenation from Cenozoic warm periods., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17106, https://doi.org/10.5194/egusphere-egu24-17106, 2024.