Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north

Christo Buizert (), Michael Sigl, Mirko Severi, Bradley R. Markle, Justin J. Wettstein, Joseph R. McConnell, Joel B. Pedro, Harald Sodemann, Kumiko Goto-Azuma, Kenji Kawamura, Shuji Fujita, Hideaki Motoyama, Motohiro Hirabayashi, Ryu Uemura, Barbara Stenni, Frédéric Parrenin, Feng He, T. J. Fudge and Eric J. Steig
Additional contact information
Christo Buizert: Oregon State University
Michael Sigl: Paul Scherrer Institute
Mirko Severi: University of Florence
Bradley R. Markle: University of Washington
Justin J. Wettstein: Oregon State University
Joseph R. McConnell: Nevada System of Higher Education
Joel B. Pedro: University of Copenhagen
Harald Sodemann: University of Bergen
Kumiko Goto-Azuma: National Institute for Polar Research
Kenji Kawamura: National Institute for Polar Research
Shuji Fujita: National Institute for Polar Research
Hideaki Motoyama: National Institute for Polar Research
Motohiro Hirabayashi: National Institute for Polar Research
Ryu Uemura: Biology and Marine Science, University of the Ryukyus
Barbara Stenni: Informatics and Statistics, Ca’ Foscari University of Venice
Frédéric Parrenin: Université Grenoble Alpes, CNRS, IRD, IGE
Feng He: Oregon State University
T. J. Fudge: University of Washington
Eric J. Steig: University of Washington

Nature, 2018, vol. 563, issue 7733, 681-685

Abstract: 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.

Keywords: Southern Hemisphere Westerly Winds; Northern Hemisphere Climate; Volcanic Markers; Atlantic Meridional Overturning Circulation (AMOC); AMOC Collapse (search for similar items in EconPapers)
Date: 2018
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Citations: View citations in EconPapers (4)

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DOI: 10.1038/s41586-018-0727-5

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