Swiss researchers forecast increasingly variable climate for Europe

Brussels, 13 Jan 2004

Swiss scientists have warned that extreme temperatures in Europe, such as those recorded in summer 2003, will become more common in the future.

The prediction is based on a study of average European temperatures since 1990 carried out by a team at the Swiss Federal Institute of Technology, and supported by the EU funded PRUDENCE project. According to their results, summer temperatures like last year's should only occur once every 46,000 years, even taking into account the effects of global warming.

'Statistically, this event should not have happened,' the Institute's Christoph Schär told the scientific journal Nature. The most obvious explanation for why it did, according to Dr Schär, is that, as well as raising temperatures, greenhouse gasses such as carbon dioxide may also increase weather variability.

To test their theory, the team ran a computer climate simulation to estimate the spread of future temperatures in Europe, and found that that extremely hot weather would become more common in the future. 'Our simulations show that, roughly speaking, every second European summer is likely to be as warm, if not warmer, than the summer of 2003,' said Dr Schär. 'I wouldn't bet on how much the variation will increase, but I'm confident that it will.'

Although some scientists in other parts of the world have rejected the Swiss team's conclusions, Dr Schär thinks that Europe may be more susceptible to variability due to its particular geography. He believes that areas most at risk are those in which a semi arid climate borders a wetter region, such as within Europe.

During the 2003 heat wave, plants and soil in temperate areas of Central Europe lost moisture, which meant less of the Sun's energy went into evaporation and instead heated the air, according to Dr Schär.

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