Effects of Climate Change and Extreme Heat in the Midwest: New Analysis of the Past 60 Years of Heat Waves

Heat waves already kill more people in the U.S. each year than hurricanes, tornadoes, floods, and lightening combined. The 20 warmest years in the U.S. have occurred since 1981. Ten of the warmest years occurred in the past 12 years. According to climate models, these dangerous trends in extreme heat in the US are projected to increase in the coming decades. Those most impacted will be populations vulnerable to extreme weather conditions, like the elderly, the young and those populations not acclimatized to extreme heat (such as those in the northern parts of the US). This research analyzes historical heat wave data over the last sixty years in order to evaluate trends useful for public health preparedness. Using a proven climate classification system, the research focuses on five norther tier midwest cities (Chicago, St. Louis, Cincinnati, Detroit and Minneapolis) and evaluates the frequency, character and duration of the air masses associated with extreme heat over the last 60 years. In order to evaluate possible Urban Heat Island effects, a suburban or rural local has also been analyzed for each city as well. Using a proven synoptic air mass classification system, this research analyzes the frequency of the hotter air masses and how they have increased in these midwest cities. In addition, the character and duration of those air masses has also be examined to further inform public health preparedness. For example, research has shown that people are particularly sensitive to increased nighttime temperatures and therefore this analysis evaluates possible increases in nighttime temperatures. This research also looks at possible associated excess mortality during these heat events. These changes have significant implications for public health preparedness particularly in populations most vulnerable to extreme heat.