Tornadoes in December are unusual, but not unheard of. Yet the distance of the destructive path for a single twister during this weekend’s deadly weather broke a century-old record.
Are tornados linked to climate change, similar to how devastating heat, wildfires, droughts and floods have intensified with a warming Earth?
Should we get used to more late-year tornado surprises when winter behaves like spring?
Warm weather on Friday was a crucial factor as tornadoes chewed up parts of at least five states, but whether the long-run impacts of climate change is a factor is not quite as clear, and research is still evolving. That’s in part because the U.S. is unique to the rest of the world in the number of tornadoes it records, meteorologists say.
About 1,200 twisters hit the U.S. each year, according to the NOAA National Severe Storms Laboratory.
“This event was not just unusual — it was truly historic and deeply shocking. I fear we are poking the climate beast,” said Jennifer Marlon, a climate scientist at the Yale School of the Environment, in a tweet. She, too, says that the climate change connections to tornados are “complicated.”
Some scientists say that the atmospheric conditions that give rise to such outbreaks are intensifying in the winter, extending so-called tornado season, as the planet warms. What’s more, “tornado alley” is shifting to states farther east from the Plains states that are notorious for twisters.
President Biden was asked on Saturday if he can link climate change to the weekend devestation.
“All I know is that the intensity of the weather across the board has some impacts as a consequence of the warming of the planet and climate change,” Biden said. “The specific impact on these specific storms, I can’t say at this point.”
“I’m going to be asking the EPA and others to take a look at that,” the president added. “The fact is that we all know everything is more intense when the climate is warming. Everything. And obviously it has some impact here, but I can’t give you a quantitative read on that.”
At least 64 people died in hardest-hit Kentucky, Gov. Andy Beshear said Monday, according to the Associated Press. There were at least another 14 deaths in Illinois, Tennessee, Arkansas and Missouri.
Read: Thousands of Kentucky residents without heat and water after tornadoes kill dozens
Spring-like temperatures across much of the Midwest and South in December helped bring the warm, moist air that produces thunderstorms. Some of this is due to the periodic La Nina, which generally brings warmer than normal winter temperatures to the Southern U.S.
Researchers are working to better understand how the building blocks for tornadoes, atmospheric instability and wind shear, will respond to global warming. It is likely that a warmer, more humid world would allow for more frequent instability. However, it is also possible that a warmer world would lessen chances for wind shear.
This weekend’s storms met with exceptionally strong wind shear, which appears to have prevented the tornadoes that can emerge with thunderstorms from dissipating as quickly as they typically might, weather experts said.
Tornadoes usually lose energy in a matter of minutes, but in this case it was hours, Northern Illinois University meteorology professor Victor Gensini said, according to the Associated Press. That’s partly the reason for the exceptionally long path of Friday’s storm, going more than 200 miles or so, he said. The record was 219 miles was set by a tornado that struck three states in 1925. Gensini thinks the latest will surpass that mark once meteorologists finish analyzing it.
Less than 10% of severe thunderstorms produce tornadoes, which holds back some scientists from drawing conclusions about climate change, Harold Brooks, a tornado scientist at the National Severe Storms Laboratory, told the AP.
Some scientists do expect atypical, warm weather in the winter to become more common. The U.N.’s climate panel has warned that global warming of 2°C will be exceeded during the 21st century unless rapid and deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades, achieving the goals of the 2015 Paris Agreement.
“The Gulf of Mexico is very warm. It means there’s a lot more warmth and moisture because the warmer the ocean, the more moisture that comes off of it, and that moisture and heat have been streaming into the southern half of the U.S.,” Penn State climate-change professor and author Michael Mann said on MSNBC, as he made connections between climate change and unusual storms.
In a recent study, John Allen, associate professor of meteorology at Central Michigan University, said he and colleagues found that the rate of increase in severe storm environments will be greater in the Northern Hemisphere, and that it increases more at higher latitudes.
“In the U.S., our research suggests that for each 1 degree Celsius (1.8 F) that the temperatures rises, a 14%-25% increase in favorable environments is likely in spring, fall and winter, with the greatest increase in winter,” Allen says in a commentary on The Conversation. “This is driven predominantly by the increasing energy available due to higher temperatures. Keep in mind that this is about favorable environments, not necessarily tornadoes.”
But others said all storms should not be considered under the same climate-change umbrella.
“Tornados are not becoming more frequent; the average remains about 1,200 observed each year… Warming might change when ‘tornado season’ hits, but no scientific studies have yet shown any such link,” the New York Post editorial staff wrote, with a warning that higher energy costs with the elimination of fossil fuels
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will bring more damage to U.S. households.
“The link between tornadoes and climate change is currently unclear. Current data on tornadoes is inconsistent because measuring the presence of tornadoes relies on eyewitness accounts and aftermath damage assessments rather than quantifiable data,” said policy analysts at the Center for Climate and Energy Solutions, which advocates to include market-based approaches to slowing climate change.
“Additionally, it is difficult to identify long-term trends in tornado records, which only date back to the 1950s in the U.S., because the population in many areas affected by tornadoes has grown, contributing to increased eyewitness reports and greater property in harm’s way. Improved technology, such as advanced radar, also helps us ‘see’ tornadoes that may not have been detected decades ago,” the group said, addressing whether or not the number of tornadoes is on the rise.
The Associated Press contributed.