Stable isotope record of benthic foraminifera in sediment cores in the oceans

The relative flux of North Atlantic Deep Water (NADW) out of the Atlantic can be monitored in the Southern Ocean, where high delta13C NADW mixes rapidly with low delta13C recirculated Pacific water before forming Antarctic Bottom Water (AABW). By using delta13C measured in benthic foraminifera as a water mass tracer, it is shown that the Southern Ocean was dominated by Pacific water, with little NADW contribution during the last glaciation. These tracer results document the direct physical connection between insolation controlled Northern Hemisphere oscillations and changes in the chemical and physical properties of Southern Ocean water.