Reducing fossil fuel use and adapting to climate change already underway could result in major health benefits, according to a new study co-authored by Dr. Howard Frumkin, dean of the University of Washington School of Public Health.

The study, published in the Journal of the American Medical Association, also warned that some U.S. cities could experience triple the number of extremely hot days by mid-century.

The study was released to coincide with the U.N. Climate Summit. The authors analyzed climate data projections and reviewed 56 scientific papers on climate change and health. Their analysis found that by 2050, cities such as New York and Milwaukee may have three times their current average number of days hotter than 90 degrees Fahrenheit. Climate-related health risks include more extreme heat waves and storms; increased waterborne and infectious disease risks; more chronic health risks related to air pollution; and increased malnutrition and obesity-related risks from unhealthy, carbon-intensive, diets.

"Climate change already is affecting global health," said lead author Dr. Jonathan Patz, director of the University of Wisconsin-Madison Global Health Institute. "The good news is that clear health benefits are immediately available, from low-carbon strategies that today could result in cleaner air or to more active transport options that can improve physical fitness, ultimately saving lives and averting disease." Those health benefits, in turn, would also lead to economic benefits, the study says.

Study authors also include UW-Madison Drs. Tracey Holloway and Daniel Vimont, associate professors in the Nelson Institute of Environmental Studies and the department of atmospheric and oceanic sciences, and Dr. Andrew Haines, professor of public health and primary care at the London School of Hygiene and Tropical Medicine.