'Extreme Heat' Days Triple Since 1980s, and More Are Coming

By the researchers' estimates, 1.7 billion urban dwellers -- or almost one-fifth of the planet -- were exposed to a rising number of extreme heat days between 1983 and 2016.

'Extreme Heat' Days Triple Since 1980s, and More Are Coming
sun in sky

By the researchers' estimates, 1.7 billion urban dwellers -- or almost one-fifth of the planet -- were exposed to a rising number of extreme heat days between 1983 and 2016.