Guest essay by Dan Sutter
Tornadoes killed 553 Americans in 2011, the deadliest year since 1925. May 22nd marked the 10th anniversary of the Joplin, Missouri tornado, which killed 161 people. That was the first three-digit number since 1953. The United States had recorded an average of 60 tornado deaths per year.
This death toll shocked the public, weather forecasters and researchers. Improvements to weather radar, warnings from the National Weather Service, and the advent of real-time street-level tracking had apparently made such fatalities a historical relic.
Some experts had an answer to the devastation: human-made climate change. Bill McKibben went in the Washington Post with the headline “A Link Between Climate Change and Joplin Tornadoes? Never! “He said
“When you see pictures of debris like this week from Joplin, Missouri, don’t be surprised: Does this have anything to do with the tornado outbreak three weeks ago in Tuscaloosa, Ala., Or the huge eruption a few weeks ago? ”
Researchers Kevin Trenbeth and Michael Mann also stated that global warming is making tornadoes worse in Grist, saying, “It would be irresponsible not to mention climate change.”
When the unexpected happens, researchers need to ask why and examine the data. Kevin Simmons and I had just published a book on the social impact of tornadoes. We wanted to investigate whether the 2011 death toll was due to the tornadoes that occurred, societal vulnerability, or some other factor. We have published our findings in a book, Deadly Season: 2011 Tornado Outbreak Analysis, and an article in Natural Hazards Review.
Our conclusion: It was the tornadoes. The total number of tornadoes rated EF-5 on the Fujita Extended Scale for Tornado Damage, the highest rating, gives a short answer. Six EF-5 tornadoes occurred in 2011, including four in Mississippi and Alabama on April 27. The nation has, on average, less than one per year (59 since 1950), only one since 2011. The year’s activity was extreme, but not unprecedented. For example, in the EForn eruption on April 3, 1974, seven EF-5s occurred.
Historical ratios of deaths per injury, per million dollar property damage or per damaged building provide more detailed information and relationships. For example, prior to 2011, violent tornadoes killed one person for $ 20 million in property damage each. This and similar conditions remained constant in 2011. The many violent tornadoes on long stretches of the year caused enormous damage with the corresponding victims.
We also used statistical models of tornado deaths to study the effects of Doppler radar and NWS warnings. The models are checked for tornado and path characteristics such as EF scale, path length and number of people and mobile homes in the affected counties. Adding the features of 2011 tornadoes to the model would give a death estimate based on the most recent patterns.
The analysis predicted more than 500 deaths for the tornadoes of the year with a high probability that one tornado would kill more than 100 people. Note that the deadliest tornado over the years used in statistical analysis (1990-2010) killed 36 people. The 2011 tornadoes were unlike anything we had seen in decades.
Before 2011, there was no upward trend in violent tornadoes. The year was a clear statistical outlier or a Black Swan-type event. As a result, we concluded that due to previous improvements in the warning process, deaths should return to normal or continue to decrease. In contrast, climate change advocates told us that Joplin and Tuscaloosa were the new normal due to global warming.
The US has killed an average of 43 tornadoes over the past nine years, including 76 in the deadliest year (2020). We’ve only had 11 deaths so far in 2021 (though knock on some wood as you read).
Mother nature can be extreme, variable and capricious. Events and years, unlike recent experiences, are inevitable. When unexpected (or unimaginable) weather events occur, we should try to figure out what happened and why, rather than sluggishly ascribing it to man-made global warming.
Daniel Sutter (dsutter@troy.edu) is Charles G. Koch Professor of Economics and Director of the Manuel H. Johnson Center for Political Economy at Troy University and host of discussions about TrojanVision.
Addendum from Anthony
A picture is worth a thousand words, a graphic says even more.
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