Extreme Heat

Abstract

Extreme heat events (EHEs) are periods of high temperatures and humidity that are considered to be unusual for a specific geographic location. For example, in 1995 an extended heat wave in Chicago, Illinois, in the United States was blamed for the deaths of 550 citizens. Most of the dead were elderly, poor individuals who may not have realized that heat could kill, or who had no means of mitigating the rising temperatures in their homes or any way to escape to a cooler environment. In 2003, Europe was subjected to an EHE that is estimated to have resulted in the deaths of 70,000, with 15,000 of those deaths in Paris, France. “Extreme heat” is a relative term. Individuals adapt to their local climate, so it is difficult to use an absolute number to describe the conditions meteorologists consider a relative change from past conditions. The Centers for Disease Control and Prevention (CDC) defines extreme heat as “summertime temperatures that are substantially hotter and/or more humid than average for location at that time of year.” According to the Public Health Institute’s Center for Climate Change, the state of California defines extreme heat days as those days above the 98th percentile of maximum temperatures based on 1961–1990 data for a specific location. Crucial to understanding extreme heat events is the collection of data about temperature and humidity. The US Global Change Research Program provides heat wave data spanning 1961 to 2018. The site links to a variety of programs related to global climate modeling. The National Resources Defense Council is a nongovernmental organization that has excellent maps which show change over time in the frequency of extreme heat events that overlay the human impact of these events. The National Centers for Environmental Information provides graphic data of current weather conditions along with lists of significant climate anomalies. The site has links to weather records and tools. All of these sites rely on the National Oceanic and Atmospheric Administration for their data. There are equivalent agencies all over the world. The World Meteorological Organization, part of the United Nations, is also a valuable resource for data.