EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Arctic closure as a trigger for Atlantic overturning at the Eocene-Oligocene Transition

David Hutchinson1,2, Helen Coxall1,2, Matt O'Regan1,2, Johan Nilsson2,3, Rodrigo Caballero2,3, and Agatha de Boer1,2
David Hutchinson et al.
  • 1Department of Geological Sciences, Stockholm University, Stockholm, Sweden
  • 2Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 3Department of Meteorology, Stockholm University, Stockholm, Sweden

The Eocene-Oligocene Transition (EOT), approximately 34 Ma ago, marks a period of major global cooling and inception of the Antarctic ice sheet. Proxies of deep circulation suggest a contemporaneous onset or strengthening of the Atlantic meridional overturning circulation (AMOC). Proxy evidence of gradual salinification of the North Atlantic and tectonically driven isolation of the Arctic suggest that closing the Arctic-Atlantic gateway could have triggered the AMOC at the EOT. We demonstrate this trigger of the AMOC using a new paleoclimate model with late Eocene boundary conditions. The control simulation reproduces Eocene observations of low Arctic salinities. Subsequent closure of the Arctic-Atlantic gateway triggers the AMOC by blocking freshwater inflow from the Arctic. Salt advection feedbacks then lead to cessation of overturning in the North Pacific. These circulation changes imply major warming of the North Atlantic Ocean, and simultaneous cooling of the North Pacific, but no interhemispheric change in temperatures.

How to cite: Hutchinson, D., Coxall, H., O'Regan, M., Nilsson, J., Caballero, R., and de Boer, A.: Arctic closure as a trigger for Atlantic overturning at the Eocene-Oligocene Transition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7493,, 2020


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