Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperate reconstruction
Chris S. M. Turney1,2, Christopher J. Fogwill1,2, Jonathan G. Palmer1,2, Erik van Sebille3,4, Zoë Thomas1,2, Matt McGlone5, Sarah Richardson5, Janet M. Wilmshurst5,6, Pavla Fenwick7, Violette Zunz8,9, Hugues Goosse8, Kerry-Jayne Wilson10, Lionel Carter11, Mathew Lipson1,3, Richard T. Jones12, Melanie Harsch13, Graeme Clark14, Ezequiel Marzinelli14,15, Tracey Rogers14, Eleanor Rainsley16, Laura Ciasto17, Stephanie Waterman1,3,18, Elizabeth R. Thomas19, and Martin Visbeck201Climate Change Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Australia 2Palaeontology, Geobiology and Earth Archives Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Australia 3ARC Centre of Excellence for Climate System Science, University of New South Wales, Australia 4Grantham Institute and Department of Physics, Imperial College London, UK 5Landcare Research, PO Box 690 40, Lincoln 7640, New Zealand 6School of Environment, University of Auckland, New Zealand 7Gondwana Tree - Ring Laboratory, P.O. Box 14, Little River, Canterbury 7546, New Zealand 8Université catholique de Louvain, Earth and Life Institute, Georges Lemaître Centre for Earth and Climate Research, Place Pasteur, 3, 1348 Louvain - la - Neuve, Belgium 9Earth System Science and Departement Geogra fie, Vrije Universiteit Brussels, Belgium 10West Coast Penguin Trust, P.O. Box 70, Charleston 7865, West Coast, New Zealand 11Antarctic Research Centre, University of Victoria, Wellington, New Zealand 12Department of Geography, Exeter University, Devon, EX4 4RJ, UK 13Department of Biology, University of Washington, Seattle, Washington, USA 14Evolution and Ecology Research Centre, School of Biological, Earth and Envir onmental Sciences, University of New South Wales, Australia 15Sydney Institute of Marine Science, Chowder Bay Rd, Mosman NSW 2088, Australia 16Wollongong Isotope Geochronology Laboratory, School of Earth and Environmental Sciences, University of Wollongong, NSW 2522, Australia 17Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway 18Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada 19British Antarctic Survey, Cambridge, UK 20GEOMAR Helmholtz Centre for Ocean Research Kiel and Kiel University, Germany
Received: 09 Nov 2016 – Accepted for review: 16 Nov 2016 – Discussion started: 21 Nov 2016
Abstract. Occupying 14% of the world’s surface, the Southern Ocean plays a fundamental role in global climate, ocean circulation, carbon cycling and Antarctic ice-sheet stability. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54˚S). Our annually-resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the mid-twentieth century, a phenomenon predating the observational record. Climate reanalysis and modelling shows a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer.
Turney, C. S. M., Fogwill, C. J., Palmer, J. G., van Sebille, E., Thomas, Z., McGlone, M., Richardson, S., Wilmshurst, J. M., Fenwick, P., Zunz, V., Goosse, H., Wilson, K.-J., Carter, L., Lipson, M., Jones, R. T., Harsch, M., Clark, G., Marzinelli, E., Rogers, T., Rainsley, E., Ciasto, L., Waterman, S., Thomas, E. R., and Visbeck, M.: Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperate reconstruction, Clim. Past Discuss., doi:10.5194/cp-2016-114, in review, 2016.