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| European heatwaves 'have doubled' | European heatwaves 'have doubled' |
| (2 days later) | |
| The duration of heatwaves in Western Europe has doubled since 1880, a study has shown. | The duration of heatwaves in Western Europe has doubled since 1880, a study has shown. |
| The authors of the research also discovered that the frequency of extremely hot days has nearly tripled in the past century. | The authors of the research also discovered that the frequency of extremely hot days has nearly tripled in the past century. |
| The study shows that many previous assessments of daily summer temperature change underestimated heatwaves in Western Europe by about 30%. | The study shows that many previous assessments of daily summer temperature change underestimated heatwaves in Western Europe by about 30%. |
| The research appears in the Journal of Geophysical Research - Atmospheres. | The research appears in the Journal of Geophysical Research - Atmospheres. |
| The team found that heatwaves lasted an average of three days now, with some lasting up to 13 days. This compares with an average of about 1.5 days in 1880. | The team found that heatwaves lasted an average of three days now, with some lasting up to 13 days. This compares with an average of about 1.5 days in 1880. |
| Paul Della-Marta, from MeteoSwiss in Zurich, Switzerland, and colleagues analysed daily maximum temperature data from 54 recording stations across Europe. | Paul Della-Marta, from MeteoSwiss in Zurich, Switzerland, and colleagues analysed daily maximum temperature data from 54 recording stations across Europe. |
| We're getting stronger heat waves or perhaps summers that are not so strong in terms of heat - relative to an increasing trend. This is a major cause for concern Paul Della-Marta, MeteoSwiss | |
| Forty-six hold records dating back to the 19th Century; others go back to the early 1900s. The data sets come from as far north as Finland, as far south as Spain and as far east as Croatia. | Forty-six hold records dating back to the 19th Century; others go back to the early 1900s. The data sets come from as far north as Finland, as far south as Spain and as far east as Croatia. |
| In the past, however, thermometers were not kept in modern Stevenson screens. | In the past, however, thermometers were not kept in modern Stevenson screens. |
| These wooden shelters protect thermometers from direct sunlight and indirect radiation coming from the ground, both of which distort temperature readings. | These wooden shelters protect thermometers from direct sunlight and indirect radiation coming from the ground, both of which distort temperature readings. |
| Once the researchers had corrected for these effects, they found a "warm bias" in observations made prior to the introduction of these screens. In other words, temperatures were recorded as being hotter than they really were. | Once the researchers had corrected for these effects, they found a "warm bias" in observations made prior to the introduction of these screens. In other words, temperatures were recorded as being hotter than they really were. |
| This in turn meant the increase in temperature over time appeared to be smaller than it actually was. | This in turn meant the increase in temperature over time appeared to be smaller than it actually was. |
| Hot zone | Hot zone |
| The authors of the latest study also corrected for other biases in the variability of summer temperatures. | The authors of the latest study also corrected for other biases in the variability of summer temperatures. |
| We can expect more extremes of temperature in future"After looking at the records more closely, we believe... heat waves have been underestimated by about 30% over the entire Western European region," Dr Della-Marta told the BBC News website. | We can expect more extremes of temperature in future"After looking at the records more closely, we believe... heat waves have been underestimated by about 30% over the entire Western European region," Dr Della-Marta told the BBC News website. |
| "We see a doubling of the length of heatwaves and we also see a tripling in the frequency of one-off events." | "We see a doubling of the length of heatwaves and we also see a tripling in the frequency of one-off events." |
| The results support the idea that the western European climate in summer is becoming more variable - that the range of temperatures had increased. "We're getting stronger heat waves or perhaps summers that are not so strong in terms of heat - relative to an increasing trend. This is a major cause for concern," Dr Della-Marta explained. | |
| The heatwave experienced by Europe in 2003 had major adverse socio-economic and environmental effects. | The heatwave experienced by Europe in 2003 had major adverse socio-economic and environmental effects. |
| Thousands of elderly people died. Forests were devastated by fire, water ecosystems were strained, and the total mass of Alpine glaciers shrank by 10%. | Thousands of elderly people died. Forests were devastated by fire, water ecosystems were strained, and the total mass of Alpine glaciers shrank by 10%. |
| The authors say we can expect extreme weather events like this to occur more frequently in future. | The authors say we can expect extreme weather events like this to occur more frequently in future. |
| The paper's other authors were Malcolm Haylock, from re-insurer PartnerRe in Zurich and formerly of the Climate Research Unit at the University of East Anglia, UK, Jurg Luterbacher and Heinz Wanner, both of the University of Bern, Switzerland. | |
| Paul.Rincon-INTERNET@bbc.co.uk | Paul.Rincon-INTERNET@bbc.co.uk |