As health workers carried out COVID-19 tests in public squares in Washington in July, work had to be suspended as temperatures in the paved spaces soared to what felt like 110 degrees Fahrenheit (43 Celsius).
The heat-wilted U.S. city of Phoenix, meanwhile, has already seen planes delayed from taking off when airport temperatures hit 120 F (48 C). And soaring thermometers in Los Angeles this summer led tens of thousands to lose power for days.
In Greece, rising heat is now "one of our city's greatest challenges", Athens Mayor Kostas Bakoyannis told an online event in August.