Wind-driven upwelling in the ocean around Antarctica regulates the exchange of CO2 and other gases between the deep sea and the atmosphere.  Diatom productivity and burial of biogenic opal in marine sediments south of the Antarctic Polar Front are linked to the rate of upwelling, which supplies dissolved Si to the euphotic zone of the Southern Ocean.  We find enhanced rates of opal burial during the termination of the last ice age in each sector of the Southern Ocean.  In the record with the greatest temporal resolution, we find evidence for two intervals of enhanced upwelling, concurrent with the two intervals of rising atmospheric CO2 concentration during deglaciation.  These results provide the first direct evidence linking increased ventilation of deep water masses in the Southern Ocean to the deglacial rise in atmospheric CO2.

We suggest that the deglacial increase in upwelling of the Southern Ocean was a response to extreme cold conditions in the Northern Hemisphere during the time intervals surrounding Heinrich Event 1 and the Younger Dryas.  Paleo proxy records and model simulations both point to a reorganization of atmospheric circulation at these times, including a southward shift in the Intertropical Convergence Zone as well as a southward shift in the Southern Hemisphere westerlies.  The increased wind stress at the latitude of the Drake Passage associated with the southward displacement of the westerlies was instrumental in breaking down glacial ocean stratification while increasing the upwelling and ventilation of deep waters around Antarctica, as described by Toggweiler (Paleoceanography, 2006, doi10.1029/2005PA001154).