Extreme climatic events and their evolution under changing climatic conditions

This short introductory paper illustrates some key issues concerning extremes by focusing on daily temperature extremes defined using quantiles and threshold exceedances. The examples include both a low- and a high-elevation site in the Swiss Alps where long records of homogenous daily data are readily available. The analysis of extremes highlights several features, some of them taken from the 2003 heat wave that affected Europe, in particular significant changes in the trends of quantiles in the course of the 20th century, differences in the altitudinal behavior of maximum or minimum temperatures, and close links between means and the extreme quantiles of daily temperatures.