The heatwave is back in France. As the second heatwave of the summer reaches its peak on Monday, August 12, Météo France has placed 40 departments under orange alert, calling on the population to protect themselves from possible hyperthermia or heatstroke. Although the heatwave is not exceptional in terms of intensity or duration, previous summers have shown that each prolonged rise in temperature causes deaths, particularly among the elderly.

In 2023, an estimated 47,690 people died from heat in Europe between June and September, according to a study published Monday in the journal Nature Medicine. It is the second deadliest year since 2015. In 2022, nearly 62,000 people died during the summer heatwave. While the summer of 2023 was the hottest on record globally, it was only the fifth hottest in Europe, where the summer of 2022 remains to this day the one marked by the greatest heatwaves. "The 57.5% of heat-related mortality in 2023 is attributable to two episodes occurring in mid-July, between July 10 and 23, and in late August, between August 14 and 27," said Elisa Gallo, an Italian post-doctoral fellow at the Barcelona Institute for Global Health (ISGlobal), and the first author of the paper.

The team of ISGlobal researchers, who conducted their study in 35 European countries representing a population of 543 million, also observed that heat-related mortality rates were, unsurprisingly, highest in southern Europe, particularly in Greece (393 deaths per million inhabitants), Bulgaria (229) and Italy (209). In France, Santé Publique France estimates that heatwaves caused the deaths of over 5,000 people in 2023 and almost 7,000 in 2022, i.e. mortality rates of between 70 and 100 deaths per million inhabitants.

The populations most at risk remain the elderly, especially those over 80, and women. Both populations are known to produce less perspiration, the main mechanism enabling the body to cool itself by draining the heat produced by the muscles to the outside of the body.

But the increase in this heat burden is not inexorable, despite the ever-increasing impact of global warming. Spanish researchers analyzed what would have happened if temperatures in the summer of 2023 had occurred during the period 2000-2004, marked by the extreme heatwave of 2003. The result: In such a scenario, the number of deaths would have been 80% higher in the general population and twice as high in the over-80s. These data demonstrate the very positive impact of adaptation measures taken over the last 20 years, and the growing awareness of health authorities following the 2003 massacre, when over 15,000 people died over the course of two weeks in France.

You have 39.51% of this article left to read. The rest is for subscribers only.