The heatwave that hit western Europe in late July would have been "about 1.5 ° to 3 ° C lower", without the climate change attributable to human activities, according to the calculations of a group of scientists published Friday .
Temperature records were broken in several countries during this brief but intense heat wave: 42.6 ° C in Paris and Lingen, Germany, 41.8 ° C in Begijnendijk, northern Belgium, and 40.4 ° C in the south of the Netherlands. Unprecedented temperatures were also reached in the United Kingdom, with 38.7 ° C in Cambridge. The heat wave went back to Scandinavia.
But "without human-induced climate change, a heat wave as exceptional as this one would have had temperatures about 1.5 to 3 ° C lower," according to researchers at the World Weather Attribution Network.
The probability of such an event occurring in France has been multiplied by ten
The scientists took as reference the three hottest consecutive days during this hot episode.
For France, by combining different models, scientists estimate that "the probability of such an event occurring has been multiplied by at least ten," according to their report. "Such an event would have had an extremely low probability of occurring" without climate change in France, says the study.
Regarding the heat wave that hit the Hexagon end of June, scientists had already calculated that it had been made "at least five times more likely" than if the man had not altered the climate.
The heat waves are not without danger for human health, remind these scientists, with risks of excess mortality in the elderly, deaths by drowning but also deaths of people having practiced physical activity in the heat.
Drought and fires
In August 2003, more than two weeks of heat wave had resulted in an excess mortality of 15,000 people in France and more than 70,000 throughout Europe.
The heat had highlighted malfunctions in the health services and the isolation of the elderly, the main victims of the heat wave. Subsequently, the authorities drew up a "heat wave" plan every summer to protect the elderly, disabled, homeless and very young children.
Cities like Paris are also taking action, such as opening night parks or refurbished rooms. The excess mortality figures for the heat wave episode of June are expected at the beginning of August. Those for the heat wave of late July should be made public back to school.
79 French departments concerned with water restrictions
The last two heat waves have also disrupted rail transport in France, Belgium, the Netherlands, Germany and the United Kingdom because of brush fires along the tracks or damage to infrastructure by extreme heat. .
The heat also reinforces the problem of drought and the risk of leaving a forest fire or thatch. In France, for example, 79 departments are affected by water restrictions.
These heat waves are expected to multiply and intensify under the effect of global warming. Over the past 2,000 years, global temperatures have never risen so rapidly, according to data released in late July in two separate studies in Nature and Nature Geoscience.
June 2019 was also the hottest June ever recorded in the world, particularly because of the exceptional heat wave in Europe. July could be similar and break the July 2016 record, according to preliminary data from the European Copernicus Climate Change Service and the World Meteorological Organization, based on the first 29 days of July.