High temperatures during the first two weeks of August in 2003 led to an estimated 40,000 heat-related deaths across Europe. In 2004, researchers at ETH Zurich demonstrated that such heatwaves are likely to become regular events as global temperatures rise, with their length increasing by a factor of two to five by the end of the century.

Now, Erich Fischer and Christoph Schär, also of ETH Zurich, have identified the areas most at risk. ‘We wanted to find out whether future risk zones could be localised despite the considerable uncertainties in the future development of the climatic factors affecting health,’ Fischer said.

Using six new climate models with a resolution of 25 kilometres, they found that the river valleys of southern Europe, such as the Po Valley and the lower reaches of the Danube, and the Mediterranean coast, are likely to be hardest hit. The main factors, the researchers said, were the lower altitude and the comparatively high absolute humidity, which amplifies the health impacts during a heatwave.

Of concern is the fact that most of the high-risk areas are densely populated, with cities such as Milan, Athens and Naples likely to be affected.

August 2010