Ice Age changes: Antarctic sea ice and sea-surface temperature in the Southwest Pacific Ocean and their relationship to ocean circulation, marine productivity, and atmospheric carbon dioxide concentrations

Antarctic sea ice is hypothesized to have played an important role in modulating ocean circulation, marine productivity, and atmospheric carbon dioxide (CO2) concentrations on glacial-interglacial timescales; however, few reconstructions exist to directly link them. Here I reconstruct past winter sea ice concentration, sea surface temperature, and biogenic opal burial in a marine sediment core from the Southern Ocean over the last 140,000 years. The results suggest that Antarctic sea ice expansion was not a major contributor to CO2 drawdown early in the glacial cycle, but a weakening of meridional temperature gradients could have contributed to early atmospheric CO2 drawdown via their impact on air-sea gas exchange. Furthermore, sea-ice expansion appears linked to reductions in intermediate water mass production. Opal burial was high during the Holocene period and reduced during times of sea-ice expansion. Opal reductions may also be associated with southward migrations in the Antarctic Polar Front during warming periods.