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Determining the natural length of the current interglacial

Nature Geoscience volume 5, pages 138141 (2012) | Download Citation

  • An Erratum to this article was published on 01 February 2012

This article has been updated


No glacial inception is projected to occur at the current atmospheric CO2 concentrations of 390 ppmv (ref. 1). Indeed, model experiments suggest that in the current orbital configuration—which is characterized by a weak minimum in summer insolation—glacial inception would require CO2 concentrations below preindustrial levels of 280 ppmv (refs 2, 3, 4). However, the precise CO2 threshold4,5,6 as well as the timing of the hypothetical next glaciation7 remain unclear. Past interglacials can be used to draw analogies with the present, provided their duration is known. Here we propose that the minimum age of a glacial inception is constrained by the onset of bipolar-seesaw climate variability, which requires ice-sheets large enough to produce iceberg discharges that disrupt the ocean circulation. We identify the bipolar seesaw in ice-core and North Atlantic marine records by the appearance of a distinct phasing of interhemispheric climate and hydrographic changes and ice-rafted debris. The glacial inception during Marine Isotope sub-Stage 19c, a close analogue for the present interglacial, occurred near the summer insolation minimum, suggesting that the interglacial was not prolonged by subdued radiative forcing7. Assuming that ice growth mainly responds to insolation and CO2 forcing, this analogy suggests that the end of the current interglacial would occur within the next 1500 years, if atmospheric CO2 concentrations did not exceed 240±5 ppmv.

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Change history

  • 10 January 2012

    The PDF of this Letter originally appeared with the incorrect 'published online' date of 8 January 2012; the actual date it went live was 9 January 2012. The date is now correct on all versions of the Letter.


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We are grateful to members of the Past Interglacials (PIGS) working group of the Past Global Changes (PAGES) project, especially B. Thompson, A. Landais and J. McManus, for discussions. We thank R. Preece and M. Maslin for comments on the manuscript and D. Oppo for providing ODP980 data. H.F.K. acknowledges support from the Research Council of Norway, AMOCINT project; P.C.T. acknowledges support from the UK Natural Environment Research Council. This is a contribution to the PAGES PIGS project.

Author information


  1. Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT, UK

    • P. C. Tzedakis
  2. Department of Geological Sciences, University of Florida, Gainesville, Florida 36211, USA

    • J. E. T. Channell
  3. Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK

    • D. A. Hodell
    •  & L. C. Skinner
  4. Department of Earth Science and the Bjerknes Centre for Climate Research, University of Bergen, N-5007 Bergen, Norway

    • H. F. Kleiven
  5. UNI Research AS, N-5007 Bergen, Norway

    • H. F. Kleiven


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All authors contributed to the ideas developed in the paper. P.C.T. wrote the paper, with contributions from the other authors.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to P. C. Tzedakis.

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