Dynamics of the Antarctic Circumpolar Current and deep Southern Ocean oxygenation linked to atmospheric CO2 variation over the past million years
Oceanography
Final Report Abstract
The largest reservoir of remineralized carbon in the Southern Ocean and the dynamics of the Antarctic Circumpolar Current (ACC) are regarded as key components for understanding and explaining Pleistocene climate change on orbital to millennial timescales. This project aims to reconstruct the spatio-temporal variability in ACC strength over the past million years based on independent physical and chemical proxies using marine sediment cores retrieved from the Southern Ocean. This proeject investigates variations of the ACC flow speed based on a meridional transect of sediment cores from the Indian sector of the Southern Ocean. We find zonally asymmetric changes in ACC strength across the Southern Ocean on orbital timescales over the past one million years. These asymmetric changes are attributed to changes in jet streams, buoyancy forcing, and current confluence. During warmer-than-present intervals of the Pleistocene, the ACC strength was weaker in the South Indian Ocean but stronger in the South Pacific, suggesting a similar response of the ACC in response to future climate warming. Another objective is to reconstruct past changes in deep water oxygenation to unravel the processes modulating global overturning circulation changes. This task provide new constraints to distinguish Southern Ocean processes linked to CO2 variations over the past million years. With consequences from this project advance our understanding of the connection between climate and ACC dynamics and the Southern Ocean processes linked to CO2 variations in the past, which will thus increase our ability to better project its future behavior in the face of anthropogenic climate change.
Publications
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Reconstructions of the Antarctic Circumpolar Current over the past million years. 14th ICP, 2022
Wu, S., Mazaud, A., Michel, E., Lamy, F. & Jaccard, S.
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A multiproxy reconstruction of the Antarctic Circumpolar Current over the past million years. Goldschmidt2023 abstracts. European Association of Geochemistry.
Wu, Shuzhuang; Mazaud, Alain; Michel, Elisabeth; Lamy, Frank & Jaccard, Samuel
