The heatwave that caused havoc across Britain and the European continent last year has put 2003 in the record books. It was the hottest summer in more than 500 years, say climate experts.
Scientists at the University of Bern found that not only was last year an exceptionally hot summer, but that in the past 10 years Europe has experienced the hottest summers since 1500 AD.
Jürg Luterbacher and his colleagues collected data from meteorological stations around Europe to compile an accurate record of temperatures dating back to 1659. To reach further back in time they studied diaries kept by monks and scientists that accurately described the weather and signs of the changing seasons, such as flowers blooming and lakes freezing.
"The records are surprisingly accurate and reliable," said Dr Luterbacher.
The records show that Europe was on average 2C (4F) hotter last summer than the average summer temperature over nearly the entire 20th century. Some parts of continental Europe were up to 6C hotter last summer.
According to the study published in today's journal Science, the team found that winters too had become far more mild in recent years, with the coldest winter on record dating back to 1708.
Europeans who were caught out by last year's heatwave should get used to the idea, said Dr Luterbacher. "We don't know if it will get warmer every year, but the trend is certainly in that direction," he said. "The problem is that many people in Europe don't know how to cope when they happen."
Simon Brown, an expert in extreme events at the Met Office's Hadley Centre for Climate Prediction and Research in Exeter said natural variations in the Earth's climate are unlikely to explain the changes.
"We expect the temperature to keep rising over Europe. In the worst case, which is if developing countries become major greenhouse gas emitters, we anticipate Europe to be around 6C hotter by the 2080s," he said.