Jan 11, 2004

The role of increasing temperature variability in European summer heatwaves

Christoph Schär, Pier Luigi Vidale, Daniel Lüthi, Christoph Frei, Christian Häberli, Mark A. Liniger, Christof Appenzeller
  • Analyzes instrumental observations and reconstructions of global and hemispheric temperature evolution, which reveal a pronounced warming during the past approx150 years
  • States that one expression of this warming is the observed increase in the occurrence of heatwaves, understood conceptually as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small
  • Shows that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years
  • Finds that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account
  • Proposes that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003
  • Simulates possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe