The effects on organisms were accentuated by humidity, the absence of wind or the heat of urban concrete… Europe experienced a record number of days in 2023 where the heat felt was “extreme” for human bodies , due to temperatures above 35°C or 40°C.
“The year 2023 reached a record number of days of extreme heat stress, that is to say days where the temperature felt exceeded the equivalent of 46°C,” according to a report from the European Copernicus Observatory and the World Meteorological Organization (WMO) published Monday April 22. This “heat stress” index takes into account the effect on the human body of temperature combined with other factors (humidity, wind, radiation).
In addition to heatwaves, the continent suffered numerous extreme weather events during the year: two million people were affected by floods or storms, severe droughts affected the Iberian Peninsula and eastern Europe and the largest forest fire in the history of the continent devastated 96,000 hectares in Greece, says this annual report from the Copernicus Climate Change Service (C3S), produced with the UN agency responsible for weather issues. , climate and water.
These disasters cost 13.4 billion euros, 80% attributable to flooding during a year marked by rainfall well above average, note the two institutions.
Health impact
Their report focuses particularly on the health impact of heatwaves, while global warming makes summers increasingly hot and deadly on the continent. “We are seeing an upward trend in the number of days of heat stress in Europe, and 2023 was no exception” with this new record, which is however not quantified in the report, said Rebecca Emerton, climatologist at Copernicus.
To measure this thermal comfort, the C3S and the WMO refer to the Universal Thermal Climate Index (UTCI in English) which represents the heat experienced by the human body by taking into account not only the temperature, but also the humidity. , wind speed, sunshine and heat emitted by the environment, the effect of which is more pronounced in cities where materials (concrete, tar, etc.) absorb more solar radiation.
The index, expressed as the equivalent of a “felt temperature” in degrees Celsius, includes ten different categories: from extreme cold stress (beyond -40) to extreme hot stress (+ 46) including the absence heat stress (between 9 and 26). Prolonged exposure to heat stress increases the risk of illness and is particularly dangerous for vulnerable people.
Measures “soon to be insufficient”
On July 23, at the height of the heatwave, 13% of Europe was experiencing at least one degree of heat stress, unprecedented. The extreme heat hit southern Europe especially, where the air temperature reached up to 48.2°C in Sicily, 0.6 degrees below the continental record.
The figures for excess heat-related mortality in 2023 are not yet known, but the report recalls that tens of thousands of people died in Europe during the sweltering summers of 2003, 2010 and 2022. Caused by gas emissions greenhouse effect of human activity, global warming increases the intensity, duration and frequency of heatwaves.
The phenomenon is particularly visible in Europe, which is warming twice as fast as the planet’s average, whose global climate is already at least 1.2°C warmer than before the industrial era. Increased warming in Europe, combined with an aging population and an increase in the number of city dwellers, will have “serious consequences for public health”, the report adds. And “current measures to combat heat waves will soon be insufficient” to deal with it.
Globally, 2023 was the hottest year on record, driven by climate change accentuated by the return of the cyclical El Niño phenomenon. And the temperature of the oceans, which absorb 90% of the excess heat caused by humanity, remains at unprecedented temperatures for a year.