L.C. Skinner et al., Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. Posted online ahead of print on 29 April 2013; DOI: 10.1130/G34133.1.
Evidence has emerged confirming a key role for Antarctic regional climate changes in regulating atmospheric CO2 on millennial time-scales.
Using geochemical evidence from a sub-Antarctic marine sediment core, geoscientists reveal that the two pulses in atmospheric CO2 that occurred during the last deglaciation (~20,000 to 10,000 years ago) coincided with a surge in the rate at which carbon was exchanged between the atmosphere and the sub-surface Southern Ocean.
While the glacial-interglacial climate cycles of the late Pleistocene (the last ~two million years) were paced by gradual changes in the seasonality of solar radiation (i.e., insolation), ultimately they were driven and amplified by strong positive feedbacks within the climate system, including changes in atmospheric CO2 in particular.
In this study, L.C. Skinner and colleagues show that this deglacial pulse in ocean ventilation was not driven by the North Atlantic overturning alone, and must have involved an increase in the ventilation of southern-sourced deep waters. Their results thus confirm the removal of a physical and/or dynamical barrier to effective air-sea (CO2) exchange in the Southern Ocean during deglaciation and highlight the Antarctic region as a key locus for global climate/carbon-cycle feedbacks.