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The Weissert Event ~133 million years ago marked a profound global cooling that punctuated the Early Cretaceous greenhouse. We present modelling, high-resolution bulk organic carbon isotopes and chronostratigraphically calibrated sea surface temperature (SSTs) based on an organic paleothermometer (the TEX86 proxy), which capture the Weissert Event in the semi-enclosed Weddell Sea basin, offshore Antarctica (paleolatitude ~54 °S; paleowater depth ~500 meters). We document a ~3–4 °C drop in SST coinciding with the Weissert cold end, and converge the Weddell Sea data, climate simulations and available worldwide multi-proxy based temperature data towards one unifying solution providing a best-fit between all lines of evidence. The outcome confirms a 3.0 °C (±1.7 °C) global mean surface cooling across the Weissert Event, which translates into a ~40% drop in atmospheric pCO2 over a period of ~700 thousand years. Consistent with geologic evidence, this pCO2 drop favoured the potential build-up of local polar ice.
Bibliographical noteFunding Information:
We thank the ODP repository teams in Bremen and Kochi for providing sample material for this project. We also thank Eni Spa for financial support and permission to publish this study. The project has strongly benefitted from technical support by M. Pegoraro in Milan and D. Warok in Cologne. Funding was provided by Erasmus+ Traineeship scholarship to LC, the Milano group benefited of the fund PRIN 2017RX9XXXY awarded to E.E. and Eni SpA Research & Development provided financial support for research to E.E. and T.W. The authors also acknowledge the financial support from the University of Milan through the APC initiative and from the Italian Ministry of University (MUR) through the project “Diparti-menti di Eccellenza 2018–2022, Le Geoscienze per la Società: Risorse e loro evoluzione”.
© 2021, Crown.