Swiss tree rings reveal warm and wet summers during medieval times

Anne Kress, Sarah Hangartner, Harald Bugmann, Ulf Büntgen, David C. Frank, Markus Leuenberger, Rolf T.W. Siegwolf, Matthias Saurer

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


We present a 1200 year drought reconstruction for the European Alpine region based on carbon isotope variations of tree rings from living larch trees and historic timber. The carbon isotope fractionation at the study site is sensitive to summer precipitation, temperature, and irradiance, resulting in a stable and high correlation with a drought index for interannual to decadal frequencies and possibly beyond (r2 = 0.58 for 1901-2004, July/August). When combining this information with maximum latewood density-derived summer temperature, a strongly reduced occurrence of summer droughts during the warm A.D. 900-1200 period is evident, coinciding with the Medieval Climate Anomaly (MCA), with a shift to colder and drier conditions for the subsequent centuries. The warm-wet MCA contrasts strongly with the climate of the drought-prone warm phase of the recent decades, indicating different forcing mechanism for these two warm periods and pointing to beneficial conditions for agriculture and human well-being during the MCA in this region. Key Points A 1200-year drought reconstruction for the Swiss Alps was established The tree-ring carbon isotope ratios at the site are highly moisture-sensitive The data fill a gap in our knowledge about medieval hydroclimate

Original languageEnglish (US)
Pages (from-to)1732-1737
Number of pages6
JournalGeophysical Research Letters
Issue number5
StatePublished - Mar 16 2014
Externally publishedYes


  • Medieval Climate Anomaly
  • carbon isotopes
  • drought
  • tree-rings

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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