Cold spells in the Nordic Seas during the early Eocene Greenhouse

• Published in: Nature Communications
• Main Authors: Vickers, Madeleine L., Lengger, Sabine K., Bernasconi, Stefano M., Thibault, Nicolas, Schultz, Bo Pagh, Fernandez, Alvaro, Ullmann, Clemens V., McCormack, Paul, Bjerrum, Christian J., Rasmussen, Jan Audun, Hougård, Iben Winther, Korte, Christoph
• Other Authors: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Det Frie Forskningsråd
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2020
• Subjects: General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry; Nordic Seas; North Atlantic
• Online Access: http://dx.doi.org/10.1038/s41467-020-18558-7; https://www.nature.com/articles/s41467-020-18558-7.pdf; https://www.nature.com/articles/s41467-020-18558-7

Abstract The early Eocene (c. 56 - 48 million years ago) experienced some of the highest global temperatures in Earth’s history since the Mesozoic, with no polar ice. Reports of contradictory ice-rafted erratics and cold water glendonites in the higher latitudes have been largely dismissed due to ambiguity of the significance of these purported cold-climate indicators. Here we apply clumped isotope paleothermometry to a traditionally qualitative abiotic proxy, glendonite calcite, to generate quantitative temperature estimates for northern mid-latitude bottom waters. Our data show that the glendonites of the Danish Basin formed in waters below 5 °C, at water depths of <300 m. Such near-freezing temperatures have not previously been reconstructed from proxy data for anywhere on the early Eocene Earth, and these data therefore suggest that regionalised cool episodes punctuated the background warmth of the early Eocene, likely linked to eruptive phases of the North Atlantic Igneous Province.