Multi-proxy evidence for sea level fall at the onset of the Eocene-Oligocene transition

• Published in: Nature Communications
• Main Authors: Marcelo A. De Lira Mota, Tom Dunkley Jones, Nursufiah Sulaiman, Kirsty M. Edgar, Tatsuhiko Yamaguchi, Melanie J. Leng, Markus Adloff, Sarah E. Greene, Richard Norris, Bridget Warren, Grace Duffy, Jennifer Farrant, Masafumi Murayama, Jonathan Hall, James Bendle
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2023
• Subjects: Science; Q; Antarctic; East Antarctic Ice Sheet; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.1038/s41467-023-39806-6; https://doaj.org/article/5b2552d28b5a4c4b8e1ccc7bc7e9a59e

Abstract Continental-scale expansion of the East Antarctic Ice Sheet during the Eocene-Oligocene Transition (EOT) is one of the largest non-linear events in Earth’s climate history. Declining atmospheric carbon dioxide concentrations and orbital variability triggered glacial expansion and strong feedbacks in the climate system. Prominent among these feedbacks was the repartitioning of biogeochemical cycles between the continental shelves and the deep ocean with falling sea level. Here we present multiple proxies from a shallow shelf location that identify a marked regression and an elevated flux of continental-derived organic matter at the earliest stage of the EOT, a time of deep ocean carbonate dissolution and the extinction of oligotrophic phytoplankton groups. We link these observations using an Earth System model, whereby this first regression delivers a pulse of organic carbon to the oceans that could drive the observed patterns of deep ocean dissolution and acts as a transient negative feedback to climate cooling.