A protracted heatwave crawling across much of Europe has brought scorching temperatures to France this week, dealing a further blow to ecosystems already weakened by drought – while also putting human health at risk.
French authorities placed large swaths of southern France on the highest heat warning level – a “red alert” – on Wednesday as temperatures shot past 40°Celsius (104°F), shattering seasonal records.
Meteorologists have spoken of a “heat dome” weather pattern settling over the country, with a period of stable high pressure leading to torrid conditions and a lack of wind.
France as a whole experienced its hottest day ever recorded in the period after August 15 on Monday, according to the national weather service Météo France, which described the current heatwave as “intense, long-lasting” and occurring “particularly late in the season”.
Since 1947, only six heatwaves have been recorded in France after the August 15 mark, all of them this century.
“While heatwaves are not exceptional, what is surprising is that they should happen so late,” said climatologist Pascal Yiou, saying it was likely a consequence of climate change.
“You would normally get these types of temperatures between July 15 and August 15 – not after that,” he added.
Threat to forests, vines and crops
The latest heatwave is a new blow to fragile ecosystems across Europe, coming on the heels of a summer marked by widespread drought and devastating wildfires in Greece, Italy, Portugal and Spain.
While France has experienced relatively few forest fires this summer compared to last year, experts have flagged a heightened risk in the coming days, particularly in the country’s south.
“These high temperatures come at the end of a cycle, when trees are already weakened by the stress of the summer season,” said Serge Zaka, an expert in the ecological impact of climate change.
“This is normally the time when trees start getting a little respite,” Zaka added. “Instead, they are drying up further, meaning they become even more flammable.”
Météo France’s daily forest bulletin placed much of southeast France at high risk of fire on Wednesday. Local authorities have also closed most forest parks to the public as a precautionary measure.
The unseasonal heat comes at a critical time for farmers in areas famed for their wines and fruit production.
"As with the forests, this time of year usually marks the end of a cycle for vines and other fruit trees such as apples, pears, peaches and kiwis,” Zaka explained. “It's the time when the grape harvest and picking begin. But the plants suffer if temperatures continue to exceed 35°C.”
In places where temperatures are reaching 42°C, such as the wine-growing Rhône Valley, crops are already showing signs of weakness.
“Leaves exposed to the sun are turning brown and fruit is burning,” Zaka said. “It's too early to draw any conclusions, but there will certainly be yield losses.”
The heat could also affect sunflowers and maize, he warned, while leading to a fall in the milk yield of dairy cows that are particularly sensitive to high temperatures.
“What's most worrying is that this will be another blow to crops and ecosystems after a catastrophic 2022 and two difficult years before then,” Zaka said. “With each new extreme weather event, they emerge a little weaker.”
Water stress
The heatwave is also likely to exacerbate an ongoing drought that has left businesses and households grappling with water shortages.
According to the latest figures from the French Geological and Mining Research Bureau (BRGM), 72% of water tables remained below normal seasonal levels last month. Nearly 90 municipalities in the south are currently without drinking water and have to be supplied by tankers.
On Monday, the government ordered 15 industrial sites to cut back the amount of water they use to operate. Part of a wider water-saving plan unveiled earlier this year, the measure is designed to reduce groundwater and river abstraction in France by 10% by 2030.
Meanwhile, local authorities in several French departments have announced tighter rules on water use, including restrictions on nautical sports and bans on watering gardens, parks and golf courses.
Electricity operator EDF, which runs France’s nuclear power stations, has also issued warnings about its plants on the Rhone River amid concern that the water they rely on to cool the reactors is getting too hot.
Nuclear reactors use vast quantities of cooling water before dumping it back into rivers at much higher temperatures, potentially damaging local ecosystems.
France’s nuclear plants are legally required to slow down their output when the water temperature crosses a certain threshold – a risk EDF has so far ruled out.
‘Cannot lower our guard’
The heatwave’s impact on human health – both physical and mental – is another concern as millions return to work and schools prepare to reopen following the summer break.
“When the outside temperature rises, our body needs to adapt to ensure its temperature remains at around 37°C,” said Bruno Megarbane, head of the intensive care unit at Lariboisière Hospital in Paris. “That involves using certain regulatory mechanisms, such as sweat.”
However, extreme heat can cause such mechanisms to fail among vulnerable people, including children, the elderly and those with cardiovascular problems, putting them at risk of heat strokes.
Across Europe, at least 62,000 people died “prematurely” as a result of record heat in 2022, including more than 5,000 in France, according to a study published last month in the journal Nature Medicine.
“Fortunately, since 2003 we have understood the need for preventive measures to cope with extreme heat,” said Megarbane, referring to the severe heatwave 20 years ago that was blamed for tens of thousands of deaths across Europe.
Such measures include the creation of cooling areas in cities, adapting work hours to avoid the hottest hours, and cancelling certain outdoor events.
“This late spell of heat is a reminder that we cannot lower our guard now that the summer holidays are over, and that we must be ready to put such measures in place at any time,” Megarbane said.
He also warned of the possible repercussions on people’s mental health, noting that heatwaves lead to sleep deprivation, “with negative effects on memory and concentration”.
He said other ailments – including “growing anxiety, parasitic thoughts and mood disorders” – all threaten to become more acute as heatwaves grow in frequency and intensity.
This article was translated from the original in French.
