PARIS - Climate change alone made the record-setting heatwave that pushed temperatures in France above 45 degrees Celsius (113F) last week at least five times more likely, an international team of scientists said Tuesday.
Compared to June weather stretching back more than a century, the peak from June 26-28 was four degrees Celsius warmer than an equally rare heatwave would have been in 1900, the World Weather Attribution team told journalists in a briefing.
The role of global warming in the devastating hot spell, which also paralyzed neighboring European countries for nearly a week, is probably much greater, said Friederike Otto, acting director of the Environmental Change Institute at the University of Oxford.
"Models are very good at representing large-scale seasonal changes in temperatures," she explained.
"On localized scales, climate models tend to underestimate the increase in temperature."
The findings, presented as a report and to be published in a peer-reviewed journal, focused on metropolitan France and the southern city of Toulouse, where climate statisticians were coincidentally meeting during the heatwave.
Based purely on temperature records, extreme scorchers like the one last week are now 100 times more likely than in 1900, said Geert Jan van Oldenborgh, a senior researcher at the Royal Netherlands Meteorological Institute and co-author of the new report.
"But we are unable to say that this is just because of climate change," he said.
Air pollution, the "urban heat island" effect, soil moisture, cloud cover and a host of other factors can also affect the intensity of heatwaves.
And models designed to work on a different scale are consistently "biased" such that they underestimate temperature peaks.
France, Italy, Spain and some central European nations all posted all-time temperatures peaks, with dozens of deaths attributed to the week-long heatwave.
The final death toll is likely to be far higher, but will only show up months from now in statistical records as "excess deaths".
A 2003 heatwave in France claimed at least 15,000 lives, according to government figures.
source: news.abs-cbn.com
