Brian Haley Alan Mix Maureen Walczak Summer K. Praetorius Jianghui Du 2018 <p><span>During the last deglaciation (19,000–9,000 years ago), atmospheric CO</span>₂<span>increased by about 80 ppm. Understanding the mechanisms responsible for this change is a central theme of palaeoclimatology, relevant for predicting future CO</span>₂<span>&nbsp;transfers in a warming world. Deglacial CO</span>₂<span>&nbsp;rise hypothetically tapped an accumulated deep Pacific carbon reservoir, but the processes remain elusive as they are underconstrained by existing tracers. Here we report high-resolution authigenic neodymium isotope data in North Pacific sediment cores and infer abyssal Pacific overturning weaker than today during the Last Glacial Maximum but intermittently stronger during steps of deglacial CO</span>₂<span>&nbsp;rise. Radiocarbon evidence suggestive of relatively ‘old’ deglacial deep Pacific water is reinterpreted here as an increase in preformed&nbsp;</span>¹⁴<span>C age of subsurface waters sourced near Antarctica, consistent with movement of aged carbon out of the deep ocean and release of CO</span>₂<span>&nbsp;to the atmosphere during the abyssal flushing events. The timing of neodymium isotope changes suggests that deglacial acceleration of Pacific abyssal circulation tracked Southern Hemisphere warming, sea-ice retreat and increase of mean ocean temperature. The inferred magnitude of circulation changes is consistent with deep Pacific flushing as a significant, and perhaps dominant, control of the deglacial rise of atmospheric CO</span>₂<span>.</span></p> application/pdf 10.1038/s41561-018-0205-6 en Nature Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO2 concentrations article