Temperatures are expected to climb to 96 degrees by week’s end in the Louisville area. According to a climate report released Tuesday by the Union of Concerned Scientists, that heat could be just the beginning.
The report, titled “Killer Heat in the United States: Climate Choices and the Future of Dangerously Hot Days,” predicts temperatures around the Southeast – including Kentucky – will continue upward through the rest of this century, based on the current rate of increase.
An example is that the average days per year with a heat index of 100 or more would double by mid-century and quadruple by the late 21st century if left unchecked. By that time, the study predicts, states like Florida and Texas would be experiencing five months’ worth of those types of temperatures, often exceeding 105 degrees Fahrenheit.
Using historical precedent, the study calculated the frequency of days with heat index thresholds above 90 degrees — which is when outdoor workers tend to become susceptible to heat-related illness — as well as above 100 and 105 degrees Fahrenheit, levels when the National Weather Service generally recommends issuing heat advisories and excessive heat warnings.
To achieve the predictions, the number of high heat-index days was calculated by averaging projections from 18 climate models between the months of April and October.
The Southeast region would be the hardest hit, the analysis shows, ultimately reaching an average of 96 days annually with a heat index above 100 degrees, as well as 73 days per year with a heat index above 105 degrees and 12 “off-the-charts” days per year by century’s end.
The analysis of Kentucky shows that historically, there have been 41 days annually with a heat index above 90; that would increase to 91 days by 2050 and 120 by the end of the century.
The average of six days a year with a heat index above 100 would increase to 45 by mid-century and 76 by the year 2100. Louisville, Owensboro and Bowling Green would likely experience the worst of it.
In addition, history shows Kentucky averages one day per year with a heat index above 105, and that would increase to 26 days per year if growth continues unabated.
The report, which was written by a team of 10 made up primarily of climate scientists and other field experts, says that by taking fast action to curtail heat-trapping carbon emissions, such as meeting guidelines set by the Paris Agreement, could potentially halve the effects. Over the course of the next 75 to 80 years.
“Killer Heat” was funded by a number of foundations, including the Barr Foundation, the Energy Foundation, the Fresh Sound Foundation, The Rockefeller Foundation and others.
“This heat would cause large areas of the United States to become dangerously hot and would threaten the health, lives, and livelihoods of millions of people,” the report reads. “Such heat could also make droughts and wildfires more severe, harm ecosystems, cause crops to fail, and reduce the reliability of the infrastructure we depend on.”