Role of Antarctic sea ice on deep ocean circulation and ventilation in glacial-interglacial climates

Antarctic sea ice is believed to exert two main controls on the property distribution of the abyssal ocean: 1) it controls the formation rate and ventilation of Antarctic Bottom Waters and 2) it sets the maximum penetration depth of North Atlantic Deep Water. Both controls are expected to act during glacial climates and play a role in sequestering carbon in the deep ocean. Here, the relationships between the Antarctic sea ice, the ocean overturning circulation and the deep ocean ventilation are investigated through a series of numerical simulations of a coupled ocean--sea-ice--biogeochemical model in an idealized two-basin geometry connected to the south by a circumpolar channel. Our results show that the integrated sea ice area is well correlated with the shoaling of the North Atlantic Deep Water and the integrated buoyancy loss rate under sea ice. Furthermore, the Antarctic sea ice extent correlates with the “age” of the waters and the decrease in atmospheric pCO2. We discuss the relevance of our results for our understanding of the drawdown of atmospheric carbon dioxide during glacial climates.