“The geographical shift in tornado activity has been established through powerful statistical methods and is shown to occur during two successive 30-year periods moving from a colder weather pattern to warmer conditions,” lead author Ernest Agee, a professor in the Department of Earth, Atmospheric, and Planetary Sciences at Perdue University, said in a statement. “More research is needed to search for changing climate trends responsible for tornado formation and this geographical shift, but climate change is a distinct possibility.”
Correlation isn’t always causation though, and more data is required to firmly pin down this link. As aforementioned, tornadoes aren’t fully understood phenomena, and unlike hurricanes, they aren’t directly powered by warm sea surfaces.
However, rising sea temperatures does mean that more evaporation occurs at the surface, which ultimately increases the atmospheric moisture content. Increased air moisture, along with rapidly rising air, is known to produce more thunderstorms, and this is why they occur more in the summer – and more frequently as the world warms due to climate change.
Tornadoes form when a thunderstorm begins to rotate and a denser, rain-filled center collapses to the ground. Therefore, if thunderstorms are more frequent during warmer seasons, it stands to reason than tornadoes will be too. As for the shift towards the southeastern US, this may be due to the proximity to the warming coastal waters, and thus the increasing amounts of rising, moist air – but again, more research is needed to confirm this.
Tornado alley, here pictured in red. Dan Craggs/Wikimedia Commons; CC BY-SA 3.0