EGU2020-9899
https://doi.org/10.5194/egusphere-egu2020-9899
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Poleward shift in the Southern Ocean westerlies synchronous with the deglacial rise in atmospheric CO2

William Gray1, Robert Wills2, Elisabeth Michel1, and Masa Kageyama1
William Gray et al.
  • 1Laboratoire des Sciences du Climat et de l’Environnement (LSCE/IPSL), France
  • 2Department of Atmospheric Sciences, University of Washington, USA

The Southern Ocean westerly winds are hypothesised to play a key role in regulating atmospheric CO2 over glacial-interglacial cycles; constraints on the paleo-latitude of the westerly winds have, however, remained allusive.  Here we use changes in the spatial pattern of planktic foraminiferal ∂18O to track changes in the latitude of the Southern Ocean polar and subtropical fronts over the last deglaciation, which are closely tied to the position of the westerly winds. We find a ~5° equator-ward shift in the position of the fronts (and thus westerlies) during the last glacial maximum relative to their Holocene position. Our reconstruction shows the poleward shift in the westerlies over deglaciation closely mirrors the sub-millennial scale variability seen in the rise in atmospheric CO2. We propose that changes in the position of the westerly winds modulate CO2 via changes in the extent of Southern Ocean sea ice and circulation of the abyssal ocean. Using climate model simulations, we explore the possibility of a feedback loop by which these CO2/climatic changes may lead to further changes in the position of the westerly winds.

How to cite: Gray, W., Wills, R., Michel, E., and Kageyama, M.: Poleward shift in the Southern Ocean westerlies synchronous with the deglacial rise in atmospheric CO2, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9899, https://doi.org/10.5194/egusphere-egu2020-9899, 2020

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