The 2003 European summer heatwaves and drought –synoptic diagnosis and impacts

Europe was affected by a series of strong, persistent heatwaves during the summer of 2003. The largest positive anomalies in monthly mean temperatures were observed in June and August in a region stretching from south-west Germany across Switzerland to the eastern and southern parts of France (Figs. 1(a) and (e)). In eastern France, the northern parts of Switzerland and the German Alpine foreland, the June–August 2003 period was more than 5 degC warmer than the 1961–90 average, making 2003 the warmest summer in the above-mentioned area since at least 1864 (Schär et al. 2004; Bader and Zbinden 2003), but more likely since instrumental records began in the mid-to-late eighteenth century (Fricke 2003; Schönwiese et al. 2004). As a result, the impacts and the media interest were extraordinary. The World Health Organization (WHO) has estimated that the extreme heat caused more than 15 000 excess deaths in France, Portugal, and Italy alone (WHO 2003). In the European Alps, extreme snow and glacier melt led to such an increased level of ice and rock falls in the mountain faces that the normal climbing routes to the highest and the most famous Alpine peaks (Mont Blanc and Matterhorn) had to be closed by the local authorities. Even though summer 2003 is not amongst the driest on record in central Europe, the impacts of its dryness (Figs. 1(b), (d), and (f )) were augmented by high evapotranspiration rates and drought conditions during the previous spring. As a consequence, large losses in crop yield and extremely low discharge levels of rivers were reported in large parts of Europe. The 2003 European summer heatwaves and drought – synoptic diagnosis and impacts