Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals

• Published in: Earth and Planetary Science Letters
• Main Authors: Wilson, David, Struve, Torben, van de Flierdt, Tina, Chen, Tianyu, Li, Tao, Burke, Andrea, Robinson, Laura F.
• Other Authors: NERC, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Ocean circulation; Deglaciation; Drake Passage; Nd isotopes; Deep-sea corals; Sea-ice; GE Environmental Sciences; DAS; SDG 13 - Climate Action; GE; Antarctic; Pacific; Southern Ocean; The Antarctic; Antarc*; North Atlantic Deep Water; North Atlantic; Sea ice
• Online Access: http://hdl.handle.net/10023/23375; https://doi.org/10.1016/j.epsl.2020.116405

Financial support to DJW, TS, and TvdF was provided by the Natural Environment Research Council (NE/N001141/1), the Leverhulme Trust (RPG-398), the Grantham Institute for Climate Change and the Environment, and a Marie Curie Reintegration grant (IRG 230828). LFR acknowledges support from the Natural Environment Research Council (NE/N003861/1) and the European Research Council (278705). The sequence of deep ocean circulation changes between the Last Glacial Maximum and the Holocene provides important insights for understanding deglacial climate change and the role of the deep ocean in the global carbon cycle. Although it is known that significant amounts of carbon were sequestered in a deep overturning cell during glacial periods and released during deglaciation, the driving mechanisms for these changes remain unresolved. Southern Ocean sea-ice has recently been proposed to play a critical role in setting the global deep ocean stratification and circulation, and hence carbon storage, but testing such conceptual and modelling studies requires data constraining past circulation changes. To this end, we present the first deglacial dataset of neodymium (Nd) isotopes measured on absolute-dated deep-sea corals from modern Lower Circumpolar Deep Water depths in the Drake Passage. Our record demonstrates deglacial variability of 2.5 εNd units, with radiogenic values of up to during the Last Glacial Maximum providing evidence for a stratified glacial circulation mode with restricted incorporation of Nd from North Atlantic Deep Water in the lower cell. During the deglaciation, a renewed Atlantic influence in the deep Southern Ocean is recorded early in Heinrich Stadial 1, coincident with Antarctic sea-ice retreat, and is followed by a brief return to more Pacific-like values during the Antarctic Cold Reversal. These changes demonstrate a strong influence of Southern Ocean processes in setting deep ocean circulation and support the proposed sea-ice control on deep ocean structure. Furthermore, by constraining the Nd ...