The cause of carbon isotope minimum events on glacial terminations

The occurrence of carbon isotope minima at the beginning of glacial terminations is a common feature of planktic foraminifera carbon isotopic records from the Indo-Pacific, sub-Antarctic, and South Atlantic. We use the delta(13)C record of a thermocline-dwelling foraminifera, Neogloboquadrina dutertrei, and surface temperature estimates from the eastern equatorial Pacific to demonstrate that the onset of delta(13)C minimum events and the initiation of Southern Ocean warming occurred simultaneously. Timing agreement between the marine record and the delta(13)C minimum in an Antarctic atmospheric record suggests that the deglacial events were a response to the breakdown of surface water stratification, renewed Circumpolar Deep Water upwelling, and advection of low delta(13)C waters to the convergence zone at the sub-Antarctic front. On the basis of age agreement between the absolute delta(13)C minimum in surface records and the shift from low to high delta(13)C in the deep South Atlantic, we suggest that the delta(13)C rise that marks the end of the carbon isotope minima was due to the resumption of North Atlantic Deep Water influence in the Southern Ocean.