Paleo records indicate that during the last deglaciation period (19,000–9,000 years ago) atmospheric CO2 level increased by about 80 ppm. A new study published in Nature Geoscience analysed neodymium (Nd) isotope data in North Pacific sediment cores to find an increase in 14C age of North Pacific subsurface waters sourced from Antarctica indicating an enhanced abyssal overturning circulation across the Southern and Pacific Oceans during the deglacial CO2 rise. The study suggests that the increased abyssal overturning circulation during the deglacial CO2 rise in turn accelerated the movement of aged carbon out of the deep ocean and the release of CO2 to the atmosphere during “abyssal flushing events”.
Du, J., Haley, B. A., Mix, A. C., Walczak, M. H., & Praetorius, S. K. (2018). Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO 2 concentrations. Nature Geoscience. https://www.nature.com/articles/s41561-018-0205-6.