Global heat waves show climate change and El Niño are a bad combo

Outdoor workers are vulnerable to prolonged heat waves like the one hitting Texas, which climate scientists warn are becoming more common. (David J. Phillip/AP)

If there's one kind of weather extreme that scientists clearly link to climate change, it's worsening heat waves.

"They are getting hotter," says Kai Kornhuber, adjunct scientist at Columbia University and scientist at Climate Analytics, a climate think tank. "They are occurring at a higher frequency, so that also increases the likelihood of sequential heat waves."