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Lookup NU author(s): Alison McAnena,
Dr Helen Talbot,
Professor Thomas Wagner
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Marine biotic crises in the Mesozoic ocean have been linked to episodes of extreme global warming. It is proposed that cooling during Cretaceous 'greenhouse' conditions may also have caused similar crises, however robust temperature records are rare and not sufficiently detailed to confirm these relationships. Here we present high-resolution records combining TEX86-derived sea-surface temperatures, organic and carbonate δ13C isotopes, calcareous nannofossil data and global biogeochemical modelling that constrain the timing and magnitude of late Aptian cooling (116-114 Ma) and associated biotic crises. The results suggest a two million-year-long ~ 5 °C cooling of surface waters, coinciding with a ~ 2 ‰ positive carbon isotope excursion, a decline in nannoconids and planktic foraminifera and increased surface-water productivity. Modelling indicates that the δ13C isotope excursion may be explained by the burial of ~ 812,000 Gigatons of carbon over ~ 2.5 Myrs, during which period the evolving Atlantic Ocean, Southern Ocean and Tethys Ocean basins likely acted as important sinks for the burial of 50% of the total global carbon. This study therefore provides evidence that global cooling during greenhouse conditions can cause perturbations to marine ecosystems and biogeochemical cycles at scales comparable to those associated with global warming.
Author(s): McAnena A, Flögel S, Hofmann P, Herrle JO, Griesand A, Pross J, Talbot HM, Rethemeyer L, Wallmann K, Wagner T
Publication type: Letter
Publication status: Published
Journal: Nature Geoscience
Print publication date: 16/06/2013
ISSN (print): 1752-0894
ISSN (electronic): 1752-0908
Publisher: Nature Publishing Group