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Originally published in Science Express on 2 December 2004
Science 24 December 2004:
Vol. 306. no. 5705, pp. 2231 - 2235
DOI: 10.1126/science.1102398
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Reports

The Duration of Forest Stages in Southern Europe and Interglacial Climate Variability

P. C. Tzedakis,1* K. H. Roucoux,1 L. de Abreu,2 N. J. Shackleton2

Foraminiferal oxygen isotope and pollen analyses from a deep-sea sequence off southwest Portugal show that the duration of temperate stages on land over the past 350,000 years varied considerably. The record shows forest contractions during intervals of low ice volume, coeval with declines in atmospheric methane, after which tree populations did not always recover. What emerges is that, although the broad timing of interglacials is consistent with orbital theory, their specific duration may be dictated by millennial variability. This complicates the prediction of the natural duration of interglacials, at least until the origin of this climate variability is understood.

1 Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds, LS2 9JT, UK.
2 Department of Earth Sciences, University of Cambridge, Godwin Laboratory, New Museums Site, Pembroke Street, Cambridge, CB2 3SA, UK.

* To whom correspondence should be addressed. E-mail: P.C.Tzedakis{at}leeds.ac.uk

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