Winter Tornadoes Will Be 9 Times Stronger By 2099 If Global Warming Isn't Curtailed: Study

In the wake of the recent deadly tornadoes that hit five states last week, a new study shows winter tornadoes will likely be nine times more powerful by 2099 if global warming doesn't slow down.

The study, which was conducted before the outbreak, looks at how tornadoes change as global warming continues. The study focuses on the strength of massive tornadoes, not how often they occur.

Jeff Trapp, head of atmospheric sciences at the University of Illinois, Urbana-Champaign and author of the study, said if carbon dioxide levels continue to rise by 2099, rare winter tornadoes could have stronger winds, extended and broader tracks of destruction, making them nine times stronger than what they currently are.

To get his results, Trapp took conditions from two significant tornadoes in 2013 and put them into a computer simulation to see the worst-case scenario for climate change by 2100. The first tornado used was a winter EF4 tornado in Hattiesburg, Mississippi, with top wind speeds of 170 mph, which injured 82 people in February. The second was a rare spring EF5 tornado in May with a top speed of 210 mph, killing 24 people in Moore, Oklahoma.

"There is a potential for events in the future that are more intense that would not have been as intense in the current climate," Trapp said.

Three climate scientists said they aren't entirely convinced based on Trapp's technique but agree there might be something interesting to his research and approach.

Kentucky, Tornado, Damage
According to a study presented at the American Geophysical Union conference on December 13, 2021, winter tornadoes like the deadly one last week that hit five states are likely to be stronger and stay on the ground longer with a wider swath of destruction as global warming continues. Above, destruction from a tornado in downtown Mayfield, Kentucky, on December 12, 2021. Gerald Herbert/AP Photo

"I'm not 100 percent sold on the technique, but it's a very interesting approach," said Harold Brooks, a scientist at the National Severe Storms Laboratory in Norman, Oklahoma. "To me the really interesting result seems to be the longer tracks for the cool season."

A single study always raises uncertainty issues, but the results make sense, said Northern Illinois University meteorology professor Victor Gensini: "One of the major components to Friday's outbreak was the broad and anomalous warm [swath of temperatures] which permitted the storm to last for what will likely be a record-breaking path length."

Trapp used worst-case scenario, which the world used to be on track for, would have another 6 degrees (3.3 degrees Celsius) or so of warming between now and the end of the century. Trapp said he will soon run simulations based on a scenario closer to the current trajectory for carbon dioxide emissions of about 3.2 degrees (1.8 degrees Celsius) warming above current levels.

Trapp found a big change on the winter storm, significantly longer and wider tracks and windspeed increases around 14 percent that added up to the nine-fold increase in power when using a formula that takes wind speed, rotation and size of path into account. Power increased 1.5 times for the spring storm, he said.

"Bearing in mind that these high-end events are still going to be rare," Trapp said.

Trapp said that's because there are two key ingredients needed for tornadoes: unstable stormy weather and wind shear. Wind shear, the difference between winds up high and near the ground, is usually stronger in the winter, but there's not as much stormy weather because it requires warm humid conditions near the ground. But as the world warms, there will be more opportunity for instability in the winter, he said.

Not peer reviewed yet, it was presented in poster form at the American Geophysical Union conference on Monday as a peak at new research to be published later.

The Associated Press contributed to this report.

Search and Rescue, Tornado, Kentucky
According to a study presented at the American Geophysical Union conference on December 13, 2021, winter tornadoes like the deadly one last week that hit five states are likely to be stronger and stay on the ground longer with a wider swath of destruction as global warming continues. Above, emergency workers bring out a tornado victim at the Mayfield Consumer Products Candle Factory after it was destroyed by a tornado with workers inside, in Mayfield, Kentucky, on December 11, 2021. John Amis / AFP/Getty Images