Temperate rainforests near the South Pole during peak Cretaceous warmth

• Published in: Nature
• Main Authors: Klages, JP, Salzmann, U, Bickert, T, Hillenbrand, C-D, Gohl, K, Kuhn, G, Bohaty, S, Tischak, J, Mueller, J, Frederichs, T, Bauersachs, T, Ehrmann, W, Van de Flierdt, T, Simoes Pereira, P, Larter, RD, Lohmann, G, Niezgodzki, I, Uenzelmann-Neben, G, Zundel, M, Spiegel, C, Mark, C, Chew, D, Francis, JE, Nehrke, G, Schwarz, F, Smith, JA, Freudenthal, T, Esper, O, Paelike, H, Ronge, T, Dziadek, R, And the Science Team of Expedition PS104
• Other Authors: Natural Environment Research Council (NERC)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Nature Research 2020
• Subjects: Science & Technology; Multidisciplinary Sciences; Science & Technology - Other Topics; AMUNDSEN SEA EMBAYMENT; ANTARCTIC ICE-SHEET; JAMES-ROSS-ISLAND; MARIE BYRD LAND; HETEROCYST GLYCOLIPIDS; WEST ANTARCTICA; COEXISTENCE APPROACH; BOUNDARY-CONDITIONS; PROXY DATA; CLIMATE; Antarctic Regions; Atmosphere; Carbon Dioxide; Fossils; Geologic Sediments; History; Ancient; Models; Theoretical; New Zealand; Pollen; Rainforest; Spores; Temperature; Science Team of Expedition PS104; General Science & Technology; Amundsen Sea; Antarctic; Byrd; Marie Byrd Land; Ross Island; South Pole; The Antarctic; West Antarctica; Antarc*; Antarctica; Ice Sheet; James Ross Island; South pole
• Online Access: http://hdl.handle.net/10044/1/76835; https://doi.org/10.1038/s41586-020-2148-5

The mid -Cretaceous was one of the warmest intervals of the past 140 million years31(Myr)1–5 driven by atmospheric CO2 levels around 1000 ppmv6. In the near absence of proximal geological records from south of the Antarctic Circle, it remains disputed whether polar ice could exist under such environmental conditions. Here we present results from a unique sedimentary sequence recovered from the West Antarctic shelf. This by far southernmost Cretaceous record contains an intact ~3 m-long network of in-situ fossil roots. The roots are embedded in a mudstone matrix bearing diverse pollen and spores, indicative of a temperate lowland rainforest environment at a palaeolatitude of ~82°S during the Turonian–Santonian (92–83 M yr). A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric CO2 contents of 1120–1680 ppmv and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo in high-CO2 climate world