Yu, JiminMenviel, LJin, Z. D.Thornalley, D.J.R.Foster, Gavin Lrohling, eelcoMcCave, NickMcManus, J. F.Dai, YuhaoRen, H.He, FengZhang, FeiChen, P. JRoberts, Andrew P.2020-02-132020-02-132041-1723http://hdl.handle.net/1885/201690During the Last Glacial Maximum (LGM; ~20,000 years ago), the global ocean sequestered a large amount of carbon lost from the atmosphere and terrestrial biosphere. Suppressed CO2 outgassing from the Southern Ocean is the prevailing explanation for this carbon sequestration. By contrast, the North Atlantic Ocean—a major conduit for atmospheric CO2 transport to the ocean interior via the overturning circulation—has received much less attention. Here we demonstrate that North Atlantic carbon pump efficiency during the LGM was almost doubled relative to the Holocene. This is based on a novel proxy approach to estimate air–sea CO2 exchange signals using combined carbonate ion and nutrient reconstructions for multiple sediment cores from the North Atlantic. Our data indicate that in tandem with Southern Ocean processes, enhanced North Atlantic CO2 absorption contributed to lowering ice-age atmospheric CO2.This work is supported by ARC Future Fellowship (FT140100993) and Discovery Projects (DP140101393 and DP190100894) and NSFC (41676026) to J.Y., DECRA (DE150100107) and Discovery (DP180100048) to L.M., NERC Advanced Fellowship to GLF (NE/D00876X/2), and Australian Laureate Fellowship (FL120100050) to E.J.R.application/pdfen-AU© The Author(s) 2019http://creativecommons.org/ licenses/by/4.0/201910.1038/s41467-019-10028-z2019-11-25Creative Commons license