Researchers at Bern University say last summer is likely to have been the hottest since at least 1500


Their study, which was published in “Science” magazine, examined European temperatures over the past 500 years

The findings confirmed that global warming is indeed taking place. Not only was 2003 the hottest summer for 500 years, but winter and summer temperatures in the three decades from 1973 to 2003 were the highest since
1500 too.

Jürg Luterbacher, who led the research team, said the rate of global warming was alarming. “We expected to find warming, but not of this magnitude,” he told. “We’ve never really seen anything like this before. There was quite a warm summer in 1757, but not on this scale.

Although other studies have already attempted to measure global warming and climate change, this was the first to look specifically at Europe, and to measure temperature change over months and seasons. “What we found is that in the late 20th and early 21st centuries the European temperatures were the warmest of the last 500 years,” Luterbacher said. “We also found that the winters between 1500 and 1900 were about 0.5 degrees centigrade colder than the winters after 1900.”

The researchers used a variety of methods to measure temperature; there are no reliable records from the 16th century, so proxy measures such as tree rings and soil cores were used. After 1750, however, fairly reliable temperature records are available for the whole of Europe. The findings showed not only that temperatures were rising, but that they were rising consistently in all areas of Europe.

But the researchers limited their study to monitoring global warming, without attempting to find out what was causing it. “It was not our aim to determine the cause,” explained Luterbacher. “What we wanted to do was analyse temperatures, and to show that the changes in the 20th century were exceptional.”

Luterbacher shares the view of most climatologists, who believe human activity is a very likely culprit. “If you were to make a computer model which would predict this scale of warming, all the natural factors such as volcanic activity or solar irradients would not cause a warming on this scale. “So we believe that human activity is one of the main reasons for the warming.”

For environmentalists and green politicians, the study will be yet another sign that mankind’s use of fossil fuels will have to change. Isabelle Chevalley, who heads an umbrella group of centre-right politicians who are concerned about the environment, hopes the study will persuade ordinary people to pay more attention to global warming. “If we want to get people to change their ways, then often we have to prove not once but twice that it’s really necessary,”. “In situations like this, people tend to think it’s always someone else who will have to change,” she continued. “But in fact it will be the small efforts of lots of people that will have an effect.”

Luterbacher confesses that he is alarmed by the scale of climate change, which he believes could become dangerous if temperatures continue to rise in this way. “There

are particular implications for the alpine environment,” he said. “Glaciers may disappear, or lose much of their mass. The permafrost will become unstable if things get warmer – this means villages at risk of avalanche or other disasters. “It’s true there are always winners and losers in these situations,” he continued. “Scandinavia, for example, would have to use less heating if the winters became milder – that would be a positive point.” “But in general I’m afraid I think the negative aspects of global warming will be much greater than the positive ones.”