Rising European temperatures linked to fossil fuels
FRESH scientific findings may have confirmed fears that the burning of fossil fuels for human activities has increased greenhouse gases in the atmosphere.
According to a British team of scientists, record-breaking heatwaves, which threaten to be worse than the hot European summers of 2003 that resulted in the death of more than 27,000 persons across the continent.
The summer temperatures of 2003 were the highest in Europe in over 500 years.
The new study, published yesterday in the journal Nature, is the work of a team led by Peter Stott from the Metrological Office's Hadley Centre for Climate Prediction and Research. They set out to estimate by how much human activities may have increased the risk of the occurrence of the 2003 heatwave.
The Hadley Centre for Climate Prediction and Research, which is part of the British Met Office, provides a focus in the United Kingdom for scientific issues associated with climate change. Researchers employed a fast NEC SX-6 supercomputer, sophisticated climate models and new statistical techniques.
"We simulated 2003 summer temperatures over Europe - with and without the effect of man's activities - and compared these with observations," explains Stott.
"We found that although the high temperature experienced in 2003 was not impossible in a climate unaltered by man, it is very likely that greenhouse gases have at least doubled the risk and our best estimate is that such a heatwave is now four times more likely as a result of human influence on climate."
Temperatures soared across Central Europe in 2003. Even the Alps, stretching from southeastern France, Switzerland, Austria, to northern Italy, heated up. Glaciers melted rapidly, swelling rivers and lakes to dangerous levels. Climbers had to be evacuated from Switzerlands Matterhorn after melting triggered the collapse of a rock face.
In London, trains were halted over fears that tracks would buckle in the heat, while in Scotland the high temperatures combined with falling water levels in rivers and streams threatened the spawning and survival of salmon.
Throughout France, Spain, Portugal, and Italy, the intense heat and dry conditions sparked deadly forest fires.
The researchers predict that the type of summer experienced in 2003 could be expected to occur as often as every other year by the middle of this century.
"We know that 2003 type hot summers and associated heatwaves won't happen every year, but continuing man-made global warming will increase the chance," Stott said. "According to our model, by the middle of this century every other summer could be even hotter than 2003."
Stott's co-author Myles Allen of the University of Oxford has also co-authored, with Richard Lord QC, a commentary on the legal implications of the research, which is published in the same edition of Nature.
"Quantifying the costs of climate change requires being able to separate natural from man-made contributions to weather risk," said Allen.
"If a dice is loaded to come up six and does so, then clearly there is a sense in which the loading helped this to happen, but when several sixes turn up, it makes no sense to ask which of these are due to the loading. In the same way, we cannot say which of the heatwaves were man-made and which were natural, but we can apportion blame for the change in risk."
Using a threshold for mean summer temperature that was exceeded in 2003, but in no other year since the start of the instrumental record in 1851, the research team estimates with a confidence level of greater than 90 percent that human influence has "at least doubled the risk of a heatwave exceeding this threshold magnitude."
Changes in the frequency of extremes are often the most sensitive aspects of climate change for ecosystems and societal responses.
Co-author Dith Stone, also of Oxford, said, "This research will help us understand how human influences on climate affect the increased risk of deaths, forest fires, and crop losses."
