Southern Ocean deglacial record supports global Younger Dryas Miriam S. Andres a; Ã , Stefano M. Bernasconi a , Judith A. McKenzie a , Ursula Ro «hl b a Geological Institute, Department of Earth Sciences, ETH-Zurich, CH-8092 Zurich, Switzerland b Geosciences Department, DFG Research Center for Ocean Margins, University of Bremen, D-28334 Bremen, Germany Received 4 May 2003; received in revised form 26 September 2003; accepted 2 October 2003 Abstract In Northern Hemisphere deglaciation records, the transition from the last glacial to the Holocene indicates a rapid returntonear-glacialconditionsduringtheYoungerDryas,whereastheirSouthernHemisphereicecorecounterparts record two separate cooling events: the Antarctic Cold Reversal and the Oceanic Cold Reversal. Spatial distribution andrelativetimingoftheseeventsinbothhemispheresarecentralforourunderstandingofcausesandmechanismsof abrupt climate change. To date, no marine record from the southern mid-latitudes conclusively demonstrates that the Younger Dryas was a significant event in the Southern Ocean. Here, we present high-resolution oxygen isotope and iron content records of a radiocarbon-dated sedimentary sequence from the Great Australian Bight, which constrains oceanic and atmospheric changes during the last deglaciation. Oxygen isotopes from planktonic foraminifera indicate two rapid cold reversals (between 13.1 and 11.1 kyr BP) separated by a brief warming. The sedimentary iron content, interpreted as a proxy for wind strength, indicates a simultaneous change in atmospheric circulation pattern. Both records demonstrate the existence of cooling events in the Southern Hemisphere, which are synchronous with the Northern Hemisphere Younger Dryas cold reversal (between 12.9 and 11.5 kyr BP). Such evidence for the spatial distribution and timing of abrupt climatic fluctuations is essential data for groundtruthing results derived from global climate models. ß 2003 Elsevier B.V. All rights reserved. Keywords: Younger Dryas; Southern Hemisphere; deglaciation; rapid climate change; interhemispheric climate linkage; Great Australian Bight 1. Introduction The transition from the Last Glacial Maximum (LGM) to the Holocene, 20^10 kyr ago, was marked by several climatic £uctuations. The Younger Dryas (YD) [1], a prominent cold rever- sal dated between 12.9 and 11.5 kyr before present (BP), marks the abrupt return to near- 0012-821X/03/$ ^ see front matter ß 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0012-821X(03)00556-9 * Corresponding author. Present address: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA. Tel.: +1-305-361-4683; Fax: +1-305-361-4632. E-mail address: mandres@rsmas.miami.edu (M.S. Andres). Earth and Planetary Science Letters 216 (2003) 515^524 R Available online at www.sciencedirect.com www.elsevier.com/locate/epsl