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ASU Now | August 17, 2020

Over the next century, climate change and population growth will subject more people to dangerous heat and cold. A new paper, The motley drivers of heat and cold exposure in 21st century U.S. cities, was published online Aug. 17 in the "Proceedings of the National Academy of Sciences." It is the first study of its kind to consider population-weighted heat and cold exposure that directly and simultaneously account for greenhouse gas and urban development-induced warming.

Authors Ashley Broadbent and Matei Georgescu of ASU's School of Geographical Sciences and Urban Planning faculty used state-of-the-art modeling tools to analyze how three key variables would affect human exposure to extreme temperatures from the beginning of this century to its end. They concentrated on the following three key factors: climate change brought about by greenhouse gas emissions, urban development-induced impacts arising from the growth of cities, and population change in individual cities.

To describe how these three variables would affect temperatures, and in turn populations, Broadbent, Georgescu and co-author Eric Scott Krayenhoff, assistant professor at the University of Guelph, Ontario, in Canada, used a metric they dubbed “person-hours,” to describe humans’ exposure to extreme heat and cold.

Importantly, areas of the United States where human exposure would increase the most is where climate change and population increase in tandem. Meanwhile, urban development has a smaller, yet not negligible effect.