With temperatures pushing into the high 90s in London (that’s above 30 for the Celsius heads), Tuesday went down as the city’s hottest June day on record. The British meteorological service has issued a rare red warning for extreme heat in the days forward, classifying the coming wave as a risk to life. Schools have been forced to close across the southern U.K., and train operators have reduced service and urged passengers to stay at home. 

From Climate Week at London’s Guildhall, a Gothic event space where the main hall struggles with air conditioning, Guterres smiled boyishly as he described the state of affairs.

“Today this city—and far beyond—are experiencing the hottest day of the year, with higher temperatures to come,” he said. “London isn’t just calling—it’s cooking.”

The extreme heat wave that has gripped the U.K. and parts of Western and Southern Europe has already turned deadly. France, Germany, Spain, and Italy have all seen temperatures push past 100° F and are under similar red alert warnings to the U.K. At least 18 people have been reported dead in France alone directly due to the heat wave, including two children, with dozens more deaths from drowning as crowds take to water bodies to cool off.

Across the continent, forecasters have warned that temperatures could rise further still before the month is out. It’s likely to be part of a new normal for its leading European economies, as climate change makes extreme heat waves more frequent and intense even early in the summer, consequently ramping up costs. 

Under a scenario where heat waves keep worsening each year, researchers at the insurance company Allianz recently modeled how the most exposed wealthy European economies might face cumulative heat-related GDP losses of 5% to 7% by 2030.

In a risk report published last month, Allianz estimated that France would end the decade as the hardest hit country, losing $240 billion owing to heat, followed by Italy with $147 billion, then Germany losing $131 billion, and finally Spain, which might have to write off $120 billion from its economy. By the time the decade is over, extreme heat might have wiped $638 billion off Europe’s largest economies.

“Extreme heat is emerging as a structural economic risk, with Europe highly exposed,” the report’s authors wrote.

Structural weaknesses

A more vulnerable population and aging infrastructure makes Europe particularly susceptible to heat episodes like the one currently sweeping the continent, a fragility that could be laid bare on countries’ balance sheets during the heat waves to come. 

Extreme weather events, including heat waves, almost always manifest as an economic drag. Last year, the impact of high heat, drought, and floods added up to €43 billion, almost $50 billion, in losses for European economies, according to a paper from Germany’s University of Mannheim.

Last year’s economic costs were mostly tied to lost productivity during high heat episodes, as well as drought and flood-driven damage to agriculture and infrastructure. But costs reflect in part the intensity of extreme weather, and for Europe, the bill is still adding up.

Europe is the world’s fastest-warming continent. Temperatures have spiked around 2.4° C over the past five years, almost twice the global average, according to the EU’s Copernicus Climate Change Service. Researchers have pointed to several reasons for this, with culprits including the continent’s geography—Europe borders the Arctic, the world’s fastest-warming region. Policy may also play a role, as researchers have found the continent’s stricter air pollution regulations likely allowed more planet-heating solar radiation to reach the Earth.

And despite its wealth, Europe might also be one of the continents least equipped to handle climate impacts such as heat waves. One in five Europeans is now older than 65, and the 80 and above demographic is the EU’s fastest-growing age group. The elderly are highly vulnerable to high temperatures, a risk compounded by European countries’ infrastructural deficiencies in a warming world.

While some 90% of buildings and households in the U.S. have air conditioning units installed, only 19% of European structures can say the same, according to the Allianz report. The lack of air conditioning is one item on a long list of “genuine structural vulnerability” facing Europe, the report warned, including dense building stock that retains heat and few countries subsidizing household cooling equipment the same way they do with heating.

That vulnerability will be the primary driver of Europe’s heat-driven economic losses in the years ahead. Research from the World Meteorological Organization published last year found productivity losses between 2% and 3% for every degree above 20°C, with constraints, with larger losses the higher temperatures get. High heat can lead to physical strain, confusion, and poor sleep, factors that all weigh down on productivity.

The economic impacts of high heat extend well beyond labor productivity. The Allianz report concluded that heat tends to dampen investment enthusiasm among companies, causing businesses to scale back spending and hiring to slow. This is in part due to lower productivity, but also comes down to higher input costs for raw materials and energy, as sweltering temperatures will likely constrain production. 

With heat waves arriving earlier and hitting harder each year, the report found that no European country is properly equipped for the scale of risk now associated with summer. The next UN chief to speak at London Climate Week in 2027 might hope to find an event hall equipped with air conditioning.