Summary

The circulation of the Pacific Ocean since the Last Glacial Maximum (LGM) remains poorly known, because of the lack of high resolution marine sediment records and carbonate materials that most circulation proxies depend on. We solve these problems in this project by generating authigenic neodymium isotope records, which are not dependent on carbonate archives, from two of the highest resolution (~250 yr) marine cores from the Gulf of Alaska (Figure 1). We found that the glacial circulation of the deep Pacific was sluggish, likely contributed to the glacial drawdown of atmospheric CO2. During the deglaciation, especially in the Northern Hemisphere stadial events (i.e., Heinrich Stadial 1 and Younger Dryas), the abyssal circulation in the Pacific strenghthend, drived by vigorous Southern Ocean overturning (Figure 2). We suggest that this strenghthening of abyssal Pacific circulation can explain the ~80 ppm rise of atmospheric CO2 during the deglaciation.

This study was recently published in Nature Geoscience:
Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO2 concentrations