Northward shift of the southern westerlies during the Antarctic Cold Reversal

Abstract

Inter-hemispheric asynchrony of climate change through the last deglaciation has been theoretically linked to latitudinal shifts in the southern westerlies via their influence over CO2 out-gassing from the Southern Ocean. Proxy-based reconstructions disagree on the behaviour of the westerlies through this interval. The last deglaciation was interrupted in the Southern Hemisphere by the Antarctic Cold Reversal (ACR; 14.7 to 13.0 ka BP (thousand years Before Present)), a millennial-scale cooling event that coincided with the Bølling–Allerød warm phase in the North Atlantic (BA; 14.7 to 12.7 ka BP). We present terrestrial proxy palaeoclimate data that demonstrate a migration of the westerlies during the last deglaciation. We support the hypothesis that wind-driven out-gassing of old CO2 from the Southern Ocean drove the deglacial rise in atmospheric CO2.