Sizzling Midwest Feels a Preview of a Hotter Future Climate

'Climate change is putting heat waves on steroids,' says prominent climate scientist, with dire consequences for public health.

Extreme heat waves like the current string of scorching days in the Midwest have become more frequent worldwide in the last 60 years, and climate scientists expect that human-caused global warming will exacerbate the dangerous trend in coming decades.  It comes with potentially life-threatening consequences for millions of people.

Research has shown that overall mortality increases by 4 percent during heat waves compared to normal days in the U.S.  A study in the journal Environmental Health Perspectives in 2011 suggested that rising summer temperatures could kill up to 2,200 more people per year in Chicago alone during the last two decades of the 21st century.

"The climate is changing faster than we've ever seen during the history of human civilization on this planet, and climate change is putting heat waves on steroids," Katharine Hayhoe, director of the Climate Science Center at Texas Tech University, said during a news conference on Thursday.  "Heat waves are getting more frequent and stronger."

Temperatures this week soared into the 90s from Minnesota to Iowa, combining with high humidity to send heat indices well above the 100-degree Fahrenheit mark, considered a threshold for conditions dangerous to human health.

Current temperatures in large parts of the Midwest have been rising steadily for more than 100 years, with accelerated warming in the past few decades.  According to the 2014 National Climate Assessment, the average temperature in the region increased by more than 1.5 degrees Fahrenheit between 1900 and 2010.  Between 1950 and 2010, the rate of increase doubled, and since 1980, the pace of warming is three times faster than between 1900 and 2010.
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"We see the biggest impacts when we have multi-day events," Hayhoe said.  "And when nighttime temperatures don't cool off enough to give us a respite, that's when we start to see an impact on health.  Especially the elderly and people with respiratory problems start flooding emergency rooms."

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