EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cenozoic CO2: from the deep ocean to the atmosphere

James Rae1 and the OldCO2NewArchives Collaborators*
James Rae and the OldCO2NewArchives Collaborators
  • 1University of St Andrews, Earth and Environmental Sciences, St Andrews, UK
  • *A full list of authors appears at the end of the abstract

The Cenozoic is a time of climatic extremes: abrupt events and state changes pepper the transition from Hothouse warmth to the Pleistocene Icehouse, and these evolving climate regimes are accompanied by major changes in ocean chemistry and biota.  CO2 is thought to play a critical role in environmental change throughout this era, but despite recent progress, there is still much to learn on the Cenozoic evolution of the ocean-atmosphere CO2 system.  To address this, we present new reconstructions of ocean pH and atmospheric CO2 spanning the late Cretaceous to the Pleistocene, based on the boron isotope composition of benthic and planktic foraminifera.  These are accompanied by improved constraints on the secular evolution of seawater chemistry, which are critical for accurate and precise determination of ocean pH and atmospheric CO2 from boron isotopes.  Using the most reliable data and updated calculation routines, we find close coupling between the CO2 system of the deep ocean, the atmosphere, and climate over the last 66 million years.  Our data also highlight intervals of dynamic changes in the carbon cycle, such as the transition into the Early Eocene Climatic Optimum, where we suggest a novel link between changes in ocean circulation, redox, and the sulphur and carbon cycles.  Overall, our data demonstrate the persistence of CO2’s control on the climate system across varying boundary conditions, and the influence of both the long-term carbon cycle and shorter-term ocean biogeochemical cycling on Earth’s climate.

OldCO2NewArchives Collaborators:

James Rae, Sarah Greene, Sandy Kirtland-Turner, Phil Sexton, Markus Adloff, Steve Barker, James Barnet, Andrea Burke, Elena Dominguez-Valdes, Matthew Dumont, David Evans, Gavin Foster, William Gray, Rosanna Greenop, Michael Henehan, David Hodell, Jo Holo, Pincelli Hull, Hana Jurikova, Matthew Kaminski, Jennifer Kasbohm, Dick Kroon, Diederik Liebrand, Lucas Lourens, Nele Meckler, Sophie Nuber, Noah Planavsky, Andy Ridgwell, Heather Stoll, Wayne Strojie, Ellen Thomas, Bridget Wade, Thomas Westerhold, Ross Whiteford, James Zachos, Martin Ziegler

How to cite: Rae, J. and the OldCO2NewArchives Collaborators: Cenozoic CO2: from the deep ocean to the atmosphere, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9880,, 2023.