Evidence for late glacial oceanic carbon redistribution and discharge from the Pacific Southern Ocean

• Published in: Nature Communications
• Main Authors: Iwasaki, Shinya, Lembke-Jene, Lester, Nagashima, Kana, Arz, Helge, Harada, Naomi, Kimoto, Katsunori, Lamy, Frank
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer Nature 2022
• Subjects: Southern Ocean
• Online Access: https://epic.awi.de/id/eprint/57548/; https://epic.awi.de/id/eprint/57548/1/s41467-022-33753-4.pdf; https://hdl.handle.net/10013/epic.13b99952-8b91-49df-991d-5cc893e9f662

Southern Ocean deep-water circulation plays an important role in the global carbon cycle. On geological time-scales, upwelling along the Chilean continental margin likely contributed to the deglacial atmospheric carbon dioxide rise, but little quantitative evidence exists of carbon storage. Here, we use a new X-ray Micro-Computer-Tomography method to assess foraminiferal test dissolution as proxy for paleo-carbonate ion concentrations [CO3^2−]. Our subantarctic Southeast Pacific sediment core depth transect shows significant deep-water [CO3^2−] variations during the Last Glacial Maximum and Deglaciation (10 – 22 ka BP). We provide evidence for an increase in [CO3^2−] during the early deglacial period (15-19 ka BP), followed by a ca. 40 µmol kg^-1 reduction in Lower Circumpolar Deepwater (CDW). This decreased Pacific to Atlantic export of low-carbon CDW contributed to significantly lowered carbon storage within the Southern Ocean, highlighting the importance of a dynamic Pacific–Southern Ocean deep-water reconfiguration for shaping late-glacial oceanic carbon storage, and subsequent deglacial oceanic-atmospheric CO2 transfer.