Wind-Driven Upwelling in the Southern Ocean and the Deglacial Rise in Atmospheric CO 2

Abstract

Wind-driven upwelling in the ocean around Antarctica helps regulate the exchange of carbon dioxide (CO ₂ ) between the deep sea and the atmosphere, as well as the supply of dissolved silicon to the euphotic zone of the Southern Ocean. Diatom productivity south of the Antarctic Polar Front and the subsequent burial of biogenic opal in underlying sediments are limited by this silicon supply. We show that opal burial rates, and thus upwelling, were enhanced 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 CO ₂ during deglaciation. These results directly link increased ventilation of deep water to the deglacial rise in atmospheric CO ₂ .