Glacial and Interglacial Changes in Southwest Pacific Water Mass Ventilation and Circulation

Abstract

On glacial/interglacial timescales, Southern Ocean air-sea gas exchange is considered to be an important factor, driving the variability of atmospheric CO2 concentrations. To understand the role of oceanic variability in the global carbon cycle, it is necessary to reconstruct changes in deep- and intermediate-water circulation and chemistry of Southern Ocean water masses. In this context,we used a transect of sediment cores to reconstruct ventilation and circulation changes of the South Pacific. The data show the presence of very old and CO2 enriched waters between 2000 and 4300 m water depth. Because the deep-water rejuvenation is parallel to the trend in atmospheric CO2, we propose that the deep Pacific Ocean significantly contributet to the deglacial rise in atmospheric CO2. Furthermore, we were able to show that the intermediate-water off New Zealand was significantly shallower during glacial stages, furthermore expanding the volume of the glacial carbon pool.