By midcentury, Midwestern cities like Minneapolis and St. Paul may become popular destinations for “environmental refugees” fleeing extreme weather on the East and West Coasts, according to some experts.

But that doesn’t mean, of course, that Minnesota is not going to have its own serious climate-change challenges — including ones related to health.

For as a paper published Monday in the Journal of the American Medical Association (JAMA) points out, the number of extremely hot days — ones with temperatures over 90 degrees — in Midwestern cities is likely to triple by 2046.

That increased heat, along with other consequences of climate change, will have wide-ranging effects on public health throughout the U.S. and the world, the authors of the paper warn.

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Below is a summary of what those authors, led by Dr. Jonathan Patz of the Global Health Institute at the University of Wisconsin in Madison, believe some of those effects are likely to be. The scientists’ predictions were made after analyzing more than 13 climates models and 56 previous studies.

Heat-related disorders. Air-conditioning has dramatically reduced, but not eliminated, heat-related deaths and illness in the United States. Between 1999 and 2009, certified heat-related deaths averaged 658 per year in the U.S. — more than from all other weather events combined. (The actual number of heat-related deaths is much greater, but if, say, a fatal heart attack is triggered by excessive heat, the death certificate is likely to cite “cardiac arrest,” not temperature, as the cause of death.)

Global warming is going to push those numbers up — significantly. It’s estimated, for example, that Chicago may see more than 2,000 extra heat-wave-related deaths per year by the end of this century. People who are elderly, living in poverty, socially isolated or have an underlying mental illness will be particularly at risk. And, yes, the authors of the JAMA paper do acknowledge that global warming will also mean fewer cold-weather-related deaths, but it’s uncertain if the lives saved in winter will outnumber those lost during the extended summer heat waves.

Respiratory disorders. The number of people suffering from respiratory disorders, including asthma, will also increase. Hot weather makes ground-level ozone (smog) worse, and in many regions of the U.S. the smog will be further fed by an increasing number of wildfires. Rising temperatures will also mean longer allergy seasons. Since 1995, the ragweed season in mid-North America has already lengthened by as much as 13 to 27 days north of the 44th parallel (which, of course, is almost all of Minnesota).

Infectious diseases. Warming temperatures will mean that disease-carrying ticks and mosquitoes will spread and thrive in areas that were once too cold for them. Lyme disease, for example, is expected to expand into Canada. In some areas of the country, climate change will bring heavier rainfall and flooding, thus also increasing the risk of gastrointestinal illnesses caused by various bacteria, noroviruses and enteroviruses.

Food insecurity. Climate change is projected to lower global food production by 2 percent per decade, even as demand increases by 14 percent. By midcentury, food prices are expected to rise rapidly, placing poor people in the U.S. and throughout the world at even greater risk of chronic hunger and undernutrition.

Mental health disorders. Floods, heat waves and wildfires — all of which are predicted to become more common as climate change intensifies during the coming years — are associated with an increased incidence of posttraumatic stress disorder (PTSD), anxiety and depression. Slow-moving disasters, such as years of drought, are also known to threaten mental health.

A call to action

Despite their sobering findings, Patz and his colleagues don’t want their paper to be viewed as a doom-and-gloom document, but rather as a call to action.

“Climate change is an enormous public health challenge because it affects our health through multiple pathways,” Patz said in a statement released with the study. “But if the risks are so interdependent, so, too, are the opportunities.”

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Here in the United States, those opportunities include increasing the use of wind, solar, wave and geothermal energy, redesigning our communities to encourage “active transportation” (walking and cycling) and decreasing our meat consumption to reduce polluting emissions associated with livestock production.

Patz presented the paper Monday at the Civil Society Event on Action in Climate Change and Health in New York City. You can read it in full through the JAMA website.