French officials urged caution Thursday as a record pre-summer heatwave spread across the country from Spain, where authorities were fighting forest fires on a sixth day of sweltering temperatures.

The Meteo France weather service said it was the earliest hot spell ever to hit the country, worsening a drought caused by an unusually dry winter and spring, and raising the risk of wildfires.

Spain, which has already seen its hottest May since the beginning of this century, was sweating under temperatures forecast as high as 43 degrees Celsius (109 Fahrenheit) and no relief is expected before Sunday, the Aemet weather service said.

At least three forest fires erupted in Catalonia, including one near Baldomar around 140 kilometres (87 miles) northeast of Barcelona, that has burned nearly 1,000 hectares (2,470 acres) but could grow to 20,000 hectares before it is contained, the regional government said.

No evacuations have yet been ordered but people are being urged to remain in their homes.

Neighbouring Portugal saw its hottest May since 1931, with most scientists attributing the early season heat across Europe to global warming caused by greenhouse gas emissions.

Scientists say heat waves have become more likely due to climate change. As global temperatures rise over time, heat waves are predicted to become more frequent and intense and last longer, and their impacts more widespread.

– 'Worst I've ever seen' –

The heatwave crossed the Pyrenees into southern France on Tuesday and was set to hit most of the country by Saturday, when thermometers could reach 39C in Paris.

Most of France was on heatwave alert, including 12 departments at the highest level in the southwest, where the education ministry advised parents to keep younger students at home if possible on Friday.

"Be alert! Hydrate, stay in cool areas, and stay in touch with those close to you," Prime Minister Elisabeth Borne said on Twitter.

Officials in Paris and other cities have also issued alerts over ozone pollution, which occurs when intense sunlight transforms carbon emissions into smog.

Paris police chief Didier Lallement has cut speed limits for the region by 10 km/h (6.2 mph) for Friday.

"I'm 86 years old, I was born here, but I think this is the worst heatwave I've ever seen," Jacqueline Bonnaud told AFP at a shaded park in the southern city of Toulouse.

Surging use of air-conditioners and fans was forcing France to import electricity from neighbouring countries, grid operator RTE said, since many of the country's nuclear reactors are offline to evaluate potential corrosion risks or for maintenance.

– 'Infrastructure suffers' –

The intense heat is also lowering river levels, meaning some nuclear plants must reduce output because water used for cooling reactors is too hot to be returned to waterways without endangering plants and wildlife.

Spain, Italy and other countries have recently limited the use of air-conditioners to save energy, and French Energy Minister Agnes Pannier-Runacher told France 2 television that she was considering the same.

"Saturday will be the peak, with temperatures of 35 to 39 degrees across most of the country," Tristan Amm, a Meteo France forecaster, told AFP.

Schools have stocked up on water and several have moved end-of-year exams to north-facing rooms, while some departments in the south have said classes will be cancelled on Friday afternoon.

Cities such as Bordeaux have also installed misting devices on the hottest squares and streets.

Rail operator SNCF has warned of potential delays as trains are forced to slow because the heat has deformed tracks or damaged electrical equipment.

"Our infrastructure suffers" in the heat, said SNCF regional director Thierry Rose, noting that track-level temperatures in Bordeaux had hit 52 Celsius (126 Fahrenheit) on Wednesday.

Deadly heatwaves threaten economies too
Paris (AFP) June 15, 2022 –

More frequent and intense heatwaves are the most deadly form of extreme weather made worse by global warming, with death tolls sometimes in the thousands, but they can also have devastating economic impacts too, experts say.

The prolonged and unseasonable scorchers gripping the central United States and rolling northward across western Europe, sending the thermometer above 40 degrees Celsius (104 degrees Fahrenheit), are likely to cause both.

Deadly and costly

Very high temperatures caused nearly 10 percent of the two million deaths attributed to extreme weather events from 1970 to 2019, according to the World Meteorological Organization.

Virtually all that heat-related mortality, moreover, has been since 2000, especially the last decade: from 2010 to 2019 scorching heat was responsible for half of 185,000 extreme weather deaths registered.

In Europe, heatwaves accounted for about 90 percent of weather-related mortality between 1980 and 2022, the European Environment Agency (EEA) has reported.

Heatwaves rack up economic costs as well, but they are harder to quantify than damage from a storm or flood, and more difficult to insure.

But extended bouts of great heat can result in more hospital visits, a sharp loss of productivity in construction and agriculture, reduced agricultural yields, and even direct damage to infrastructure. Excess mortality has an economic cost too.

The EAA estimates that heatwaves in 32 European countries between 1980 and 2000 cost 27 to 70 billion euros. The damages over the last 20 years — which included the deadly heatwave of 2003, with 30,000 excess deaths — would almost certainly be higher.

Premature death

The national public health agency in France, which will be blanketed by extreme conditions over the coming days, has called heatwaves "a mostly invisible and underestimated social burden."

In France alone, heatwaves from 2015 to 2020 cost 22 to 37 billion euros due to health expenses, loss of well-being and especially "intangible costs stemming from premature deaths".

Reduced productivity

The heatwaves of 2003, 2010, 2015 and 2018 in Europe caused damages totalling 0.3 to 0.5 percent of GDP across the continent, and up to two percent of GDP in southern regions, according to a peer-reviewed study in Nature.

This level of impact could be multiplied by five by 2060 compared to a 1981-2010 baseline without a sharp reduction in greenhouse gas emissions and measures to adapt to high temperatures, the study warned.

At sustained temperatures of around 33C or 34C, the average worker "loses 50 percent of his or her work capacity", according to the International Labor Organization (ILO).

The ICO estimates by 2030 heatwaves could reduce the total number of hours worked globally by more than two percent — equivalent to 80 million fulltime jobs — at a cost of 2.4 trillion dollars, nearly 10 times the figure for 1995.

"Climate change-related heat stress will reduce outdoor physical work capacity on a global scale," The UN's Intergovernmental Panel on Climate Change (IPCC) said in its most recent synthesis report, noting that in some tropical regions outdoor work may become impossible by the end of the century for 200 to 250 days each year.

Drought and agriculture

Both heatwaves and drought are a major threat to agriculture, and thus food security.

Long-term drought is agriculture's worst enemy when it comes to extreme weather, but heatwaves can provoke major damage as well.

In 2019, a heatwave caused a nine percent drop in drop in maize yields across France, and a 10 percent decline in wheat, according to the French agricultural ministry.

A 2012 scorcher in the United States led to a 13 percent drop in maize production, and a sharp jump in global prices.

Heatwaves also have a negative impact on livestock production and on milk production, according to the IPCC.