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Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2
journal contribution
posted on 2023-05-18, 16:26 authored by Watson, AJ, Vallis, GK, Maxim NikurashinMaxim NikurashinAtmospheric CO2 concentrations over glacial–interglacial cycles closely correspond to Antarctic temperature patterns. These are distinct from temperature variations in the mid to northern latitudes, so this suggests that the Southern Ocean is pivotal in controlling natural CO2 concentrations. Here we assess the sensitivity of atmospheric CO2 concentrations to glacial–interglacial changes in the ocean’s meridional overturning circulation using a circulation model. for upwelling and eddy transport in the Southern Ocean coupled with a simple biogeochemical description. Under glacial conditions, a broader region of surface buoyancy loss results in upwelling farther to the north, relative to interglacials. The northern location of upwelling results in reduced CO2 outgassing and stronger carbon sequestration in the deep ocean: we calculate that the shift to this glacial-style circulation can draw down 30 to 60 ppm of atmospheric CO2. We therefore suggest that the direct effect of temperatures on Southern Ocean buoyancy forcing, and hence the residual overturning circulation, explains much of the strong correlation between Antarctic temperature variations and atmospheric CO2 concentrations over glacial–interglacial cycles.
Funding
Australian Research Council
History
Publication title
Nature GeoscienceVolume
8Issue
11Pagination
861-864ISSN
1752-0894Department/School
Institute for Marine and Antarctic StudiesPublisher
Nature Publishing GroupPlace of publication
United KingdomRights statement
© 2015 Macmillan PublishersRepository Status
- Restricted