title: Pliocene reversal of late Neogene aridification.
abstract: The Pliocene epoch (5.3-2.6 Ma) represents the most recent geological interval in which global temperatures were several degrees warmer than today and is therefore considered our best analog for a future anthropogenic greenhouse world. However, our understanding of Pliocene climates is limited by poor age control on existing terrestrial climate archives, especially in the Southern Hemisphere, and by persistent disagreement between paleo-data and models concerning the magnitude of regional warming and/or wetting that occurred in response to increased greenhouse forcing. To address these problems, here we document the evolution of Southern Hemisphere hydroclimate from the latest Miocene to the middle Pliocene using radiometrically-dated fossil pollen records preserved in speleothems from semiarid southern Australia. These data reveal an abrupt onset of warm and wet climates early within the Pliocene, driving complete biome turnover. Pliocene warmth thus clearly represents a discrete interval which reversed a long-term trend of late Neogene cooling and aridification, rather than being simply the most recent period of greater-than-modern warmth within a continuously cooling trajectory. These findings demonstrate the importance of high-resolution chronologies to accompany paleoclimate data and also highlight the question of what initiated the sustained interval of Pliocene warmth.
authors: School of Earth Sciences, University of Melbourne, Parkville, VIC 3010, Australia; kale.sniderman@unimelb.edu.au.
authors: J M Kale
authors: JM
authors: Sniderman
authors: School of Earth Sciences, University of Melbourne, Parkville, VIC 3010, Australia;
authors: Jon D
authors: JD
authors: Woodhead
authors: School of Earth Sciences, University of Melbourne, Parkville, VIC 3010, Australia;
authors: John
authors: http://orcid.org/0000-0001-9427-3525
authors: J
authors: Hellstrom
authors: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia;
authors: Gregory J
authors: GJ
authors: Jordan
authors: School of Geography, University of Melbourne, Parkville, VIC 3010, Australia; Environnements, Dynamiques et Territoires de la Montagne, UMR CNRS, Université de Savoie-Mont Blanc, 73376 Le Bourget du Lac, France;
authors: Russell N
authors: RN
authors: Drysdale
authors: Department of Earth Sciences, University of Adelaide, Adelaide, SA 5001, Australia;
authors: Jonathan J
authors: JJ
authors: Tyler
authors: School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3125, Australia.
authors: Nicholas
authors: N
authors: Porch
mesh_terms: D001315:Australia; D002980:Climate; D010163:Paleontology
keywords: Neogene; aridification; paleoclimate; pollen; speleothems