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Across Europe in June, from the Czech Republic to Switzerland to Spain, new heat records tested the Continent’s defenses. Schools were shuttered. Villages were evacuated. Soldiers battled wildfires. And social workers raced to the homes of older people to prevent mass deaths.
It wasn’t only monthly records that shattered. On Friday, a town in the south of France felt like Death Valley, Calif., in August: According to the French national weather agency, Gallargues-le-Montueux was 45.9 degrees Celsius, or 115 degrees, the hottest temperature ever recorded in the country.
It is part of an unmistakable trend: The hottest summers in Europe in the last 500 years have all come in the last 17 years. Several of those heat waves bear the fingerprints of human-caused climate change. In years to come, scientists say, many more are likely to batter what is naturally one of the world’s temperate zones.
“It is quite clear one has to treat it as an emergency,” said Kai Kornhuber, a climate scientist doing postdoctoral research at the Earth Institute at Columbia University.
It is also unsurprising. As rising greenhouse gas emissions warm the planet (average global temperatures have gone up by around 1 degree Celsius, or 1.8 degrees Fahrenheit, since the dawn of the industrial age) more and more heat records are broken all over the world.
“It is premature to attribute the heat wave to climate change, but this is consistent with climate scenarios which predict more frequent, drawn out and intense heat events as greenhouse gas concentrations lead to a rise in global temperatures,” the World Meteorological Organization said Monday in a statement.
Worldwide, 2019 is on track to be among the hottest years on record, and Europe is on the front line. Its wealth and social safety net have kept it from being ravaged. Hospitals work. Paramedics respond. Farmers have crop insurance.
The number of heat waves in France has doubled in the past 34 years and is expected to double again by 2050, while their intensity is also expected to increase, according to the national weather service, Météo-France.
“This is a war, a battle on two fronts, on the front of causes and effects. We’ve got so much to do,” the French environment minister, François de Rugy, said on television Monday. “Unfortunately we’ve got to understand that these exceptional situations risk becoming more frequent.”
In the Gard region of southern France, 60 fires on Friday burned 1,500 acres. In Paris, the Fire Department responded to 20 percent more emergency calls than usual. Thousands of schools shut down.
Critically, several nighttime minimum temperature records were also broken. A series of extremely hot nights can be lethal, because it deprives the body of the recovery period that normally comes after sunset.
“This was predictable,” said Cécile Duflot, former party secretary of France’s Green Party, who is now head of Oxfam France. “France is not doing enough to limit greenhouse gases. And France is not at all prepared for these heat waves. The country pretty much stopped functioning.”
In Germany, speed limits were imposed on parts of the autobahn because extreme heat can cause roads to buckle. More than 100 runners collapsed during a half-marathon in Hamburg on Sunday.
In Spain, wildfires have destroyed 24,700 acres over the last several days in four different regions of the country, forcing the evacuation of some villages and closing some roads. In the worst affected region, Catalonia, a fire is believed to have started on a chicken farm; investigators are looking into whether it was caused by the spontaneous ignition of manure.
Last week, Italy’s Health Ministry put more than a dozen cities including Milan, Rome, Turin, Venice, Bologna and Naples on red alert as temperatures climbed above 37 degrees Celsius, or 100 Fahrenheit. Florence was still on red alert Monday.
The Civil Protection Department in Rome handed out water bottles to tourists around heavily visited landmarks.
Extreme weather events have always happened, and heat waves would occur even without global warming. But a growing field of research called attribution science allows experts to assess how much global warming has stacked the deck in favor of any given weather event. These studies typically use computer models that compare the world as it is now to one in which greenhouse-gas emissions had never occurred.
The 2018 heat wave across Northern Europe, for example, was made five times more likely by climate change, according to an assessment by a group of scientists called World Weather Attribution. The year before, in 2017, a heat wave nicknamed Lucifer, which devastated the Mediterranean, was made at least 10 times more likely by climate change.
For the 2010 heat wave scientists found an 80 percent probability that it would not have happened without climate change. And, in 2003, when temperatures in some parts of France hovered around 37 Celsius for more than a week, a later attribution study found that climate change had doubled the risk.
Researchers are carrying out a rapid assessment of the current heat wave; it was expected to be issued early Tuesday.
Researchers are increasingly citing changes in the polar jet stream, the fast-moving river of high-altitude air currents at the top of the globe, as an additional factor.
The meandering of the polar jet stream affects weather across the Northern Hemisphere. If these meanders, or ripples, are extreme, cold Arctic air can spill southward or hotter air from the middle of the planet can move north.
Some scientists have linked extreme shifts in the jet stream to global warming, theorizing that the melting of Arctic ice and the decreased temperature differential between the Arctic and lower latitudes have robbed the jet stream of some of its strength, causing it to meander more.
According to climate models, hotter temperatures go hand in hand with what Michael E. Mann, a climate scientist at Pennsylvania State University, calls a “meandering, slowed jet stream that favors stalled extreme weather regimes like the ones we are seeing right now.” The jet stream is particularly “wiggly,” he went on, when the Arctic is hot.
The Arctic has been warmer over the last five years than at any time since records began in 1900.
Reporting was contributed by Kendra Pierre-Louis, Raphael Minder, Adam Nossiter, Jason Horowitz, Megan Specia and Henry Fountain.
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