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Influence of human and natural forcing on European seasonal temperatures

Nature Geoscience volume 4, pages 99103 (2011) | Download Citation


It is the regional and seasonal expression of climate change that determines the effect of greenhouse warming on ecosystemsand society1. Whereas anthropogenic influences on European temperatures have been detected over the twentieth century2,3, it has been suggested that the impact of external influences on European temperatures before 1900 is negligible4. Here we use reconstructions of seasonal European land temperature5,6 and simulations with three global climate models7,8,9 to show that external influences on climate—such as the concentrations of stratospheric volcanic aerosols or greenhouse gases, other anthropogenic effects and possibly changes in total solar irradiance—have had a discernible influence on European temperatures throughout the past five centuries. In particular, we find that external forcing contributes significantly (p<5%) to the reconstructed long-term variability of winter and spring temperatures and that it is responsible for a best guess of 75% of the observed winter warming since the late seventeenth century. This warming is largely attributable to greenhouse-gas forcing. Summer temperatures show detectable (p<5%) interdecadal variations in response to external forcing before 1900 only. Finally, throughout the record we detect highly significant summer cooling and significant winter warming following volcanic eruptions.

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We thank E. Zorita and C. Ammann for help with data from the ECHO-G and CCSM models. We thank A. Schurer, A. Bozzo and M. Küttel for comments and discussion and three anonymous reviewers for their constructive comments. The publication was supported by NSF grant ATM-0296007, NERC grant NE/G019819/1 and NCAS. E.X. and J.L. acknowledge support by the EU/FP6 integrated project CIRCE (NO036961) and from the EU/FP7 project ACQWA (NO212250). J.L. also acknowledges support from the DFG Projects PRIME (‘Precipitation in the past millennium in Europe’) within the Priority Programme ‘INTERDYNAMIK’ and ‘Historical climatology of the Middle East based on Arabic sources back to AD 800’.

Author information


  1. School of GeoSciences, University of Edinburgh, West Mains Rd, Edinburgh EH9 3JW, UK

    • Gabriele Hegerl
    • , Simon F. B. Tett
    •  & Thomas Crowley
  2. Justus-Liebig University of Giessen, Department of Geography, Senckenbergstr. 1, D-35390 Giessen, Germany

    • Juerg Luterbacher
  3. Universidad Complutense Madrid, Ciudad Universitaria, 28040 Madrid, Spain

    • Fidel González-Rouco
  4. University of Bern, Institute of Geography and Oeschger Centre for Climate Change Research, Hallerstrasse 12, CH-3012 Bern, Switzerland

    • Elena Xoplaki


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G.H. and J.L. discussed and planned the work; G.H. carried out the analysis; J.L. and E.X. provided the reconstruction; F.G-R., E.X. and S.F.B.T. provided model data and comments/text, and T.C. provided his volcanic reconstructions and its interpretation as well as overall comments. All authors contributed to discussion, interpretation and writing of the paper.

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The authors declare no competing financial interests.

Corresponding author

Correspondence to Gabriele Hegerl.

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