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Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2


Watson, AJ and Vallis, GK and Nikurashin, M, Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2, Nature Geoscience, 8, (11) pp. 861-864. ISSN 1752-0894 (2015) [Refereed Article]

Copyright Statement

© 2015 Macmillan Publishers

DOI: doi:10.1038/ngeo2538


Atmospheric 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 60ppm 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.

Item Details

Item Type:Refereed Article
Keywords:atmospheric carbon, ocean overturning circulation, glacial climate
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Nikurashin, M (Dr Maxim Nikurashin)
ID Code:106082
Year Published:2015
Funding Support:Australian Research Council (DE150100937)
Web of Science® Times Cited:82
Deposited By:IMAS Research and Education Centre
Deposited On:2016-01-28
Last Modified:2017-10-31

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