EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Setting the tree-ring record straight

Josef Ludescher1, Armin Bunde2, Ulf Büntgen3,4,5, and Hans Joachim Schellnhuber1
Josef Ludescher et al.
  • 1Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 2Institut für Theoretische Physik, Justus-Liebig-Universität Giessen, Giessen, Germany
  • 3Department of Geography, University of Cambridge, Cambridge, United Kingdom
  • 4Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
  • 5Global Change Research Centre (CzechGlobe), Brno, Czech Republic

Tree-ring chronologies are the main source for annually resolved and absolutely dated temperature reconstructions of the last millennia and thus for studying the intriguing problem of climate impacts. Here we focus on central Europe and compare the tree-ring based temperature reconstruction with reconstructions from harvest dates, long meteorological measurements, and historical model data. We find that all data are long term persistent, but in the tree-ring based reconstruction the strength of the persistence quantified by the Hurst exponent is remarkably larger (h = 1.02) than in the other data (h = 0.52 − 0.69), indicating an unrealistic exaggeration of the historical temperature variations. We show how to correct the tree-ring based reconstruction by a mathematical transformation that adjusts the persistence and leads to reduced amplitudes of the warm and cold periods. The new transformed record agrees well with both the observational data and the harvest dates-based reconstructions and allows more realistic studies of climate impacts. It confirms that the present warming is unprecedented.

How to cite: Ludescher, J., Bunde, A., Büntgen, U., and Schellnhuber, H. J.: Setting the tree-ring record straight, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19795,, 2020


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