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Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north.
Buizert, Christo; Sigl, Michael; Severi, Mirko; Markle, Bradley R; Wettstein, Justin J; McConnell, Joseph R; Pedro, Joel B; Sodemann, Harald; Goto-Azuma, Kumiko; Kawamura, Kenji; Fujita, Shuji; Motoyama, Hideaki; Hirabayashi, Motohiro; Uemura, Ryu; Stenni, Barbara; Parrenin, Frédéric; He, Feng; Fudge, T J; Steig, Eric J.
Affiliation
  • Buizert C; College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA. buizertc@oregonstate.edu.
  • Sigl M; Laboratory of Environmental Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
  • Severi M; Department of Chemistry 'Ugo Schiff', University of Florence, Florence, Italy.
  • Markle BR; Department of Earth and Space Science, University of Washington, Seattle, WA, USA.
  • Wettstein JJ; College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
  • McConnell JR; Geophysical Institute and Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway.
  • Pedro JB; Desert Research Institute, Nevada System of Higher Education, Reno, NV, USA.
  • Sodemann H; Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
  • Goto-Azuma K; Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia.
  • Kawamura K; Geophysical Institute and Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway.
  • Fujita S; National Institute for Polar Research, Tachikawa, Tokyo, Japan.
  • Motoyama H; National Institute for Polar Research, Tachikawa, Tokyo, Japan.
  • Hirabayashi M; National Institute for Polar Research, Tachikawa, Tokyo, Japan.
  • Uemura R; National Institute for Polar Research, Tachikawa, Tokyo, Japan.
  • Stenni B; National Institute for Polar Research, Tachikawa, Tokyo, Japan.
  • Parrenin F; Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Okinawa, Japan.
  • He F; Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Venice, Italy.
  • Fudge TJ; Université Grenoble Alpes, CNRS, IRD, IGE, Grenoble, France.
  • Steig EJ; College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
Nature ; 563(7733): 681-685, 2018 11.
Article in En | MEDLINE | ID: mdl-30487614
ABSTRACT
The mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling1, carbon exchange with the deep ocean2, Agulhas leakage (transport of Indian Ocean waters into the Atlantic)3 and possibly Antarctic ice-sheet stability4. Meridional shifts of the Southern Hemisphere westerly winds have been hypothesized to occur5,6 in parallel with the well-documented shifts of the intertropical convergence zone7 in response to Dansgaard-Oeschger (DO) events- abrupt North Atlantic climate change events of the last ice age. Shifting moisture pathways to West Antarctica8 are consistent with this view but may represent a Pacific teleconnection pattern forced from the tropics9. The full response of the Southern Hemisphere atmospheric circulation to the DO cycle and its impact on Antarctic temperature remain unclear10. Here we use five ice cores synchronized via volcanic markers to show that the Antarctic temperature response to the DO cycle can be understood as the superposition of two modes a spatially homogeneous oceanic 'bipolar seesaw' mode that lags behind Northern Hemisphere climate by about 200 years, and a spatially heterogeneous atmospheric mode that is synchronous with abrupt events in the Northern Hemisphere. Temperature anomalies of the atmospheric mode are similar to those associated with present-day Southern Annular Mode variability, rather than the Pacific-South American pattern. Moreover, deuterium-excess records suggest a zonally coherent migration of the Southern Hemisphere westerly winds over all ocean basins in phase with Northern Hemisphere climate. Our work provides a simple conceptual framework for understanding circum-Antarctic temperature variations forced by abrupt Northern Hemisphere climate change. We provide observational evidence of abrupt shifts in the Southern Hemisphere westerly winds, which have previously documented1-3 ramifications for global ocean circulation and atmospheric carbon dioxide. These coupled changes highlight the necessity of a global, rather than a purely North Atlantic, perspective on the DO cycle.

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: Nature Year: 2018 Document type: Article Affiliation country: United States

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: Nature Year: 2018 Document type: Article Affiliation country: United States