Links between CO 2 , glaciation and water flow: reconciling the Cenozoic history of the Antarctic Circumpolar Current

The timing of the onset of the Antarctic Circumpolar Current (ACC) is a crucial event of the Cenozoic because of its cooling and isolating effect over Antarctica. It is intimately related to the glaciations occurring throughout the Cenozoic from the Eocene–Oligocene (EO) transition (≈ 34 Ma) to the...

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Bibliographic Details
Published in:Climate of the Past
Main Authors: J.-B. Ladant, Y. Donnadieu, C. Dumas
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2014
Subjects:
Environmental pollution
TD172-193.5
Environmental protection
TD169-171.8
Environmental sciences
GE1-350
Antarctic
Southern Ocean
The Antarctic
Antarc*
Antarctica
Ice Sheet
Sea ice
Online Access:https://doi.org/10.5194/cp-10-1957-2014
https://doaj.org/article/b111ff1507204113bd9bec98d6fedad6
Description
Summary:The timing of the onset of the Antarctic Circumpolar Current (ACC) is a crucial event of the Cenozoic because of its cooling and isolating effect over Antarctica. It is intimately related to the glaciations occurring throughout the Cenozoic from the Eocene–Oligocene (EO) transition (≈ 34 Ma) to the middle Miocene glaciations (≈ 13.9 Ma). However, the exact timing of the onset remains debated, with evidence for a late Eocene setup contradicting other data pointing to an occurrence closer to the Oligocene–Miocene (OM) boundary. In this study, we show the potential impact of the Antarctic ice sheet on the initiation of a strong proto-ACC at the EO boundary. Our results reveal that the regional cooling effect of the ice sheet increases sea ice formation, which disrupts the meridional density gradient in the Southern Ocean and leads to the onset of a circumpolar current and its progressive strengthening. We also suggest that subsequent variations in atmospheric CO 2 , ice sheet volumes and tectonic reorganizations may have affected the ACC intensity after the Eocene–Oligocene transition. This allows us to build a hypothesis for the Cenozoic evolution of the Antarctic Circumpolar Current that may provide an explanation for the second initiation of the ACC at the Oligocene–Miocene boundary while reconciling evidence supporting both early Oligocene and early Miocene onset of the ACC.

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