title: Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch.
abstract: The warmest global climates of the past 65 million years occurred during the early Eocene epoch (about 55 to 48 million years ago), when the Equator-to-pole temperature gradients were much smaller than today and atmospheric carbon dioxide levels were in excess of one thousand parts per million by volume. Recently the early Eocene has received considerable interest because it may provide insight into the response of Earth's climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions. Climatic conditions of the early Eocene 'greenhouse world', however, are poorly constrained in critical regions, particularly Antarctica. Here we present a well-dated record of early Eocene climate on Antarctica from an ocean sediment core recovered off the Wilkes Land coast of East Antarctica. The information from biotic climate proxies (pollen and spores) and independent organic geochemical climate proxies (indices based on branched tetraether lipids) yields quantitative, seasonal temperature reconstructions for the early Eocene greenhouse world on Antarctica. We show that the climate in lowland settings along the Wilkes Land coast (at a palaeolatitude of about 70° south) supported the growth of highly diverse, near-tropical forests characterized by mesothermal to megathermal floral elements including palms and Bombacoideae. Notably, winters were extremely mild (warmer than 10 °C) and essentially frost-free despite polar darkness, which provides a critical new constraint for the validation of climate models and for understanding the response of high-latitude terrestrial ecosystems to increased carbon dioxide forcing.
authors.affiliation: Paleoenvironmental Dynamics Group, Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, 60438 Frankfurt, Germany. joerg.pross@em.uni-frankfurt.de
authors.forename: Jörg
authors.initials: J
authors.lastname: Pross
authors.forename: Lineth
authors.initials: L
authors.lastname: Contreras
authors.forename: Peter K
authors.initials: PK
authors.lastname: Bijl
authors.forename: David R
authors.initials: DR
authors.lastname: Greenwood
authors.forename: Steven M
authors.initials: SM
authors.lastname: Bohaty
authors.forename: Stefan
authors.initials: S
authors.lastname: Schouten
authors.forename: James A
authors.initials: JA
authors.lastname: Bendle
authors.forename: Ursula
authors.initials: U
authors.lastname: Röhl
authors.forename: Lisa
authors.initials: L
authors.lastname: Tauxe
authors.forename: J Ian
authors.initials: JI
authors.lastname: Raine
authors.forename: Claire E
authors.initials: CE
authors.lastname: Huck
authors.forename: Tina
authors.initials: T
authors.lastname: van de Flierdt
authors.forename: Stewart S R
authors.initials: SS
authors.lastname: Jamieson
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Stickley
authors.forename: Bas
authors.initials: B
authors.lastname: van de Schootbrugge
authors.forename: Carlota
authors.initials: C
authors.lastname: Escutia
authors.forename: Henk
authors.initials: H
authors.lastname: Brinkhuis
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D001272:Atmosphere / Q000737:chemistry; D002245:Carbon Dioxide / Q000032:analysis; D019069:Cell Respiration; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry; D017752:Greenhouse Effect / Q000266:history*; D049690:History, Ancient; D006802:Human Activities; D008055:Lipids / Q000032:analysis; D008962:Models, Theoretical; D010788:Photosynthesis; D011058:Pollen; D015203:Reproducibility of Results; D012621:Seasons; D013170:Spores / Q000302:isolation & purification; D013696:Temperature; D014197:Trees / Q000254:growth & development; D014329:Tropical Climate
chemical_list: D008055:Lipids; D002245:Carbon Dioxide