Climate connections between the hemisphere revealed by deep sea sediment core/ice core correlations

Correlation of Southern Ocean deep sea sediment core records with ice core records of polar climate delineates with unprecedented detail the relationship between high latitude climate and the oceanʹs thermohaline circulation over the last 80,000 years. Our observations suggest that, while North Atlantic Deep Water variability manifests itself clearly in Southern Ocean nutrient proxy records over periods as short as 500 yr, this deep water variability did not promote a direct link between climate variability in the high latitudes of the two hemispheres on millennial timescales. In particular, the proxy records indicate that, on average, northern hemisphere climate fluctuations lagged those of the southern hemisphere by 1500 yr.