Abstract

The Earth’s climate system is driven by a complex interplay of internal chaotic dynamics and natural and anthropogenic external forcing. Recent instrumental data have shown a remarkable degree of asynchronicity between Northern Hemisphere and Southern Hemisphere temperature fluctuations, thereby questioning the relative importance of internal versus external drivers of past as well as future climate variability1,2,3. However, large-scale temperature reconstructions for the past millennium have focused on the Northern Hemisphere4,5, limiting empirical assessments of inter-hemispheric variability on multi-decadal to centennial timescales. Here, we introduce a new millennial ensemble reconstruction of annually resolved temperature variations for the Southern Hemisphere based on an unprecedented network of terrestrial and oceanic palaeoclimate proxy records. In conjunction with an independent Northern Hemisphere temperature reconstruction ensemble5, this record reveals an extended cold period (1594–1677) in both hemispheres but no globally coherent warm phase during the pre-industrial (1000–1850) era. The current (post-1974) warm phase is the only period of the past millennium where both hemispheres are likely to have experienced contemporaneous warm extremes. Our analysis of inter-hemispheric temperature variability in an ensemble of climate model simulations for the past millennium suggests that models tend to overemphasize Northern Hemisphere–Southern Hemisphere synchronicity by underestimating the role of internal ocean–atmosphere dynamics, particularly in the ocean-dominated Southern Hemisphere. Our results imply that climate system predictability on decadal to century timescales may be lower than expected based on assessments of external climate forcing and Northern Hemisphere temperature variations5,6 alone.

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Acknowledgements

This work has been possible thanks to the collaboration of many members of the Australasian, South American, African and Antarctic working groups of the PAGES Regional 2K initiative. Researchers from these working groups are warmly thanked for providing metadata inventories and access to data. S. J. Phipps is acknowledged for support with model data. We acknowledge funding from the Swiss National Science Foundation and funding from the Australian Research Council (Projects LP0990151 and DE130100668) and the Australian Department of Climate Change and Energy Efficiency.

Author information

Author notes

    • Raphael Neukom

    Present address: University of Zürich, Physical Geography Division, Department of Geography, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

Affiliations

  1. Oeschger Centre for Climate Change Research, University of Bern, CH-3012 Bern, Switzerland

    • Raphael Neukom
    • , Heinz Wanner
    • , Julie Elbert
    • , Christoph C. Raible
    •  & David Frank
  2. Swiss Federal Institute WSL, Zürcherstrasse 111 CH-8903 Birmensdorf, Switzerland

    • Raphael Neukom
    •  & David Frank
  3. School of Earth Sciences, University of Melbourne, Victoria 3010, Australia

    • Joëlle Gergis
    •  & David J. Karoly
  4. ARC Centre of Excellence for Climate System Science, University of Melbourne, Victoria 3010, Australia

    • David J. Karoly
  5. Department of the Environment, Australian Antarctic Division, Kingston Tasmania 7050, Australia

    • Mark Curran
    • , Andrew D. Moy
    •  & Tas van Ommen
  6. Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart Tasmania 7000, Australia

    • Mark Curran
    • , Andrew D. Moy
    • , Tas van Ommen
    •  & Tessa Vance
  7. Departamento Astrofísica y CC de la Atmósfera, Instituto de Geociencias (CSIC-UCM) Universidad Complutense de Madrid, Madrid, 28040, Spain

    • Fidel González-Rouco
  8. Lamont-Doherty Earth Observatory, Columbia University, Palisades New York 10964, USA

    • Braddock K. Linsley
  9. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT CONICET-Mendoza, Mendoza, 5500, Argentina

    • Ignacio Mundo
    •  & Ricardo Villalba
  10. LISEA, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, B1900 La Plata, Argentina

    • Ignacio Mundo
  11. Climate and Environmental Physics, University of Bern, CH-3012 Bern, Switzerland

    • Christoph C. Raible
  12. Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle Washington 98195, USA

    • Eric J. Steig
  13. School of Earth and Environment, University of Western Australia Oceans Institute, 35 Stirling Highway Crawley WA 6009, Australia

    • Jens Zinke
  14. Australian Institute of Marine Science, Nedlands WA 6009, Australia

    • Jens Zinke

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Contributions

R.N. performed data analyses and developed the figures and tables. R.N., D.F. and J.G. led the writing of the paper. R.N., J.G., D.J.K., H.W. and D.F. designed the study. M.C., J.E., B.K.L, A.D.M., I.M., E.J.S., T.V., R.V., T.v.O. and J.Z. assisted with proxy data and F.G. and C.C.R. with climate model data. All authors discussed the results and commented jointly on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Raphael Neukom.

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DOI

https://doi.org/10.1038/nclimate2174

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