But, while scientists have been more willing to pin some extreme weather events on climate change in recent years, they're much less likely to draw a connection between warming and tornadoes for several reasons.
First, detailed data on tornadoes dates back only to the 1950s. In the mid-1990s, the widespread use of Doppler radar systems started giving researchers a better count - which is why McLeod started his count in 1995.
"Nowdays, very few tornadoes go undetected," said Luigi Romolo, McLeod's counterpart at the Southern Regional Climate Center in Baton Rouge, La. Before the 1970s, many tornadoes either went unnoticed or weren't reported unless they hit something, he said.
That relatively short and spotty record makes scientists wary of identifying a trend, said Jeff Trapp, an atmospheric scientist and professor at the University of Illinois. And it takes a combination of circumstances to produce the rotation that marks a tornado.
But some recent studies point to a higher risk of heavy thunderstorms that can produce tornadoes, while others indicate there's more of a risk of still-damaging but less dramatic effects. Others note an increase in the number of tornadoes spawned by individual outbreaks, like the deadly chain of tornadoes that ripped through the South and Midwest in April and May 2011.
That April saw 364 people killed in a total of 758 twisters, including an outbreak that ripped through Tuscaloosa and Birmingham, Ala., killing 64 and inflicting an estimated $2 billion in damage. The next month, another 326 tornadoes left another 178 dead-most of them in Joplin, Mo., where 157 died.
But other recent research suggests the increasing number of tornado clusters might be the result of factors other than climate change.
"We don't have a lot of confidence that we can distinguish these conditions and break apart, say, only storms that produce tornadoes," Trapp said. So while researchers can't say the odds of a tornado aren't getting worse, they can't say they're getting any better, either.
"We look at this general, generic category of severe thunderstorms, and our projections are an increase in the frequency of the conditions that allow for their formation," Trapp said. "But how does this all shake down in terms of their distributions across hazards - if it means more hail and fewer tornadoes, or more wind and fewer tornadoes, or does it mean more of everything? That's the question we're still working on."
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And while there's been a spike in Southeastern tornadoes the past couple of winters, McLeod said they don't seem to be getting bigger. In fact, the number of tornadoes that clocked in as a 2 or higher on the scale meteorologists use to rate the storms has gone down since the same period in the 1970s, he said.
But he warned that tornadoes can be just as deadly in the winter as in the summer - perhaps more so, because fewer people expect them.
"They think about winter as the season of snow or ice," he said. "They're not thinking about severe thunderstorms as a hazard they need to pay attention to." And when the nights are longer, "that can be a recipe for disaster."
"It's bad enough if you have a tornado coming at you during the day, but if it's at night and you're sleeping?" McLeod said. "The majority of the Georgia fatalities in this recent event were in the overnight hours when people were sleeping and caught off-guard."
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