Could Melting Arctic Ice Cause Fewer Tornadoes in the U.S.?

New research reveals that climate change affecting Arctic ice could cause a shift in American weather.

Scientists from the University of Illinois at Urbana and Purdue University studied how melting ice in the Arctic is affecting how many tornadoes occur in the United States each year. Published Monday in Climate and Atmospheric Science, the team's results describe a potential link between less ice and fewer tornadoes each year.

According to the National Severe Storms Laboratory, there are about 1,200 tornadoes in the U.S. every year. Tornado season varies across the country. On the Gulf coast, it's in the spring, in the Southern Plains, it's in May and early June, and in the upper Midwest and northern plains, it's in June and July.

The team analyzed around three decades of weather and climate data. They found that as the Arctic sea ice melts, the jet stream moves further into Canada. It typically should be in North and South Dakota.

"Tornadoes and their parent thunderstorms are fueled by wind shear and moisture," Robert Trapp, a co-author on the paper, said in a statement from the University of Illinois at Urbana. "When the jet stream migrates north, it takes the wind shear along for the ride, but not always the moisture. So, even though thunderstorms may still develop, they tend not to generate tornadoes because one of the essential ingredients for tornado formation is now missing."

The team also noticed the effect on tornados was most apparent during the month of July but they were not able to determine why. However, the team hopes that this research will help meteorologists.

"One of the reasons that we focused on sea ice is because, like the ocean and land, it is relatively slow to evolve," Trapp said. "Because sea ice and the atmosphere are coupled, the response of the atmosphere is also relatively slow. We can use this property to help make long-term predictions for tornadoes and hail, similar to the way predictions are made for hurricane seasons."

Research is still needed to understand if the tropics also play a role in the change in weather, as well as what is causing the sea ice to melt. However, Trapp said, "A relationship between Arctic sea ice and tornadoes in the U.S. may seem unlikely, but it is hard to ignore the mounting evidence in support of the connection."