London — Many Europeans have long seen air conditioning as an unnecessary, costly, carbon emissions-heavy indulgence. But as the continent's summers get hotter, claiming more lives as they do, that appears to be changing.

Over the last week, 40 people died in France from drowning as they sought relief from extreme heat. In Spain, temperatures hit 111 degrees, and the U.K. is enduring its hottest June on record. Every year, heat claims an average of 175,000 lives across Europe, according to the World Health Organization.

Air conditioning can cut heat-related deaths by 75%, according to a 2007 study, and research published by The Lancet found that in 2019, 195,000 heat-related deaths among people over the age of 65 were averted thanks to AC being adopted. 

But only about 20% of Europeans have it at home, compared to 90% in the U.S. 

So, why has it been so slow to catch on?

Culture, cost and climate

Just as Americans in Europe can't believe how much they're sweating as they walk around The Louvre in Paris, European visitors to America often find themselves appalled when — on a sunny day — they have to put on a sweater in a restaurant because the AC is blasting.

Part of Europe's reluctance to install air conditioning may come from historical stoicism — a sense that it has never been there before, so it shouldn't be needed now.  

Most of Europe, until the last few decades, really didn't need air conditioning. In southern countries, many homes were built with thick, white-painted walls, small windows and shutters to keep the sun out and cool air in. In the north, in places like Scandinavia and Britain, summers just weren't that hot.

But air conditioning is also expensive. The lack of domestic natural gas supplies in many European nations, necessitating imports, makes energy costs higher in Europe than the U.S., according to Eurelectric. Broadly, take-home salaries are also lower.

Many Europeans also feel guilt about the climate impacts of air conditioning, which accounts for 4% of global greenhouse gases, according to a 2022 study — double that of the aviation industry, for instance.

Now, though, summer in the south is so brutal that centuries of architectural trickery is being outmatched, and in the north, houses designed to retain heat during the winter have become furnaces in sweltering summers.

"All sold out"

In Italy, thousands of deaths during a 2003 heat wave appear to have been a final straw. That summer, an estimated 10-15% of households had AC units. By 2024, that number had soared to 56%, according to the National Institute of Statistics.

Italy now accounts for one-third of electricity use on air conditioning in the European Union, according to EU data.

The continent is heating up twice as quickly as the global average, according to the World Meteorological Organization, and is expected to have doubled its stock of air conditioners by 2050, according to the International Institute of Refrigeration.

In France, which experienced its "hottest days on record" this week, according to national meteorological agency Meteo-France, shops have been running out of air conditioners.

Golnaz Davarpanah, 81, who lives in a northwest Paris suburb, told CBS News on Wednesday that she and a friend went "to several stores to buy one, but they were all sold out."

"During the day it's better for me to be in my car than at home," she said. "It's surreal."

In Britain, where Thursday surpassed the record for the hottest June day ever recorded, roughly four million homes now have AC, twice as many as three years ago, according to price comparison and utility switching service USwitch. Campaign groups have urged the government to install AC in schools and care homes.

Richard Salmon, of The Air Conditioning Company, says the London firm has seen a 25-30% annual increase in installations since the residential lockdowns of the COVID-19 pandemic. But nothing like it has seen this week.

"I've been doing this for 25 years now and the last three days have been the busiest I think I've had," he told CBS News.

For Katie, who lives in east London, the cost of air conditioning — both financial and environmental — never seemed worth it.

"You just veg on the sofa and try to survive," she said. But she and her partner recently got AC after becoming parents. 

The climate guilt she feels is "nowhere near the priority of making sure that my baby has somewhere safe to sleep," she told CBS News, declining to give her full name. "Anyone who has spent a hellish hour sweatily rocking a baby to sleep would get AC, believe me."

Bob, who runs a tutoring agency in South London, said he decided to get AC after spending time in the U.S.

"As Brits, we're forced to really reflect on every decision we make that could impact the environment," he told CBS News. "Being in an environment where that isn't the case, you very easily start driving two minutes down the road and have the AC blaring."

"I was amazed at how quickly I just stopped being concerned about things," he said. "I think that is because no-one's doing any different."

Elsewhere in Europe, uptake in Germany is around 18%, close to the continent's average, while in poorer countries – and cooler countries to the north – numbers are still lower. But with warming climates, the rise of air conditioning seems inevitable for those who can afford it. 

"Concerned for my grandchildren"

To avoid widespread AC uptake exacerbating climate change, experts say modern, energy-efficient units should be installed – and run on renewable energy.

The key is solar power, according to Phil Bacon, who until last year worked to assess new environmental technologies for possible EU investment.

The power grid operator for the U.S. East Coast declared an emergency due to high demand in May as temperatures soared and people switched on their AC. Similar spikes in demand contributed to brownouts in New York City last year.

But in states like Texas, where solar power is more widespread, power supplies have remained stable during heat waves.

The EU aims to be climate neutral by 2050 and, accordingly, Spain, Italy and Greece have limited the extent to which public buildings can be cooled in the summer. 

Britain, Spain, Portugal, Latvia, Albania and the Nordic states have forged ahead with transitions to renewable energy, meanwhile. The U.K. government has introduced a program to encourage people to replace gas boilers, which have long provided both hot tap water and radiators in many homes, with modern heat pump systems. 

Heat pumps can provide both heat in the winter and cooling in the summer, and they are far more efficient to run, but they are still expensive and uptake has been slow thus far. 

The U.K.'s Climate Change Committee said in its Seventh Carbon Budget pathway — which was passed into law Wednesday — that even with increasing uptake, air conditioning could account for less than 1% of the country's electricity demand by 2050 if the right climate policies are put in place.

Bacon suggests people opt for a combination of efficient, solar-powered AC, and more old-school southern European solutions, like shutters, where possible.

If Europe continues burning fossil fuels to power a growing air conditioning habit, "the world will just continue to get hotter and hotter," he told CBS News. "I'm concerned for my grandchildren. It's going to be pretty grim."