"Historic" tornadoes devastated multiple states in a single night. Climate change could make future tornado disasters even deadlier.

A series of deadly tornadoes ripped across at least six states on Friday, killing more than 80 people in what experts have called a "historic" weather event. The twisters have devastated communities — and experts say these kinds of weather events may only get deadlier as climate change moves coastal populations inland to vulnerable areas.

The tornadoes hit several states on Friday night, including Kentucky, Mississippi, Missouri, Tennessee, Arkansas and Illinois, completely flattening entire communities and leaving homes and trees in shreds. In Kentucky alone, at least 74 people were confirmed dead as of Monday morning, as Governor Andy Beshear. declared the storm the "worst tornado event" in the state's history.

Experts believe that some of the tornadoes may have been EF-4 or EF-5, meaning they had winds of at least 166 miles per hour. 

Victor Gensini, an extreme weather and climate researcher at Northern Illinois University, told CBSN on Monday that the U.S. averages about 1,500 tornadoes a year, about 25 of which happen in December. But the last tornado "even remotely close" to this weekend's storm was in March 1925, when more than 600 people were killed. 

That tornado, he said, was on the ground for roughly 219 miles, while the one that just hit the U.S. is believed to have been on the ground for roughly 250, making it the "most historic tornado event in history." 

"The events of Friday are historic, legendary, generational — pick your favorite adjective," Gensini said. 

Many experts have pointed to climate change as part of the reason for the catastrophic events, echoing past warnings that global warming will undoubtedly fuel extreme weather. 

KCBS meteorologist Evelyn Taft told CBS News on Monday that the stark contrast in temperatures of the Northeast and Eastern U.S. created a "perfect setup for such a big storm."

"We had very cold polar air — 30 degrees in Minneapolis — and then 80-degree temperatures in Memphis— record-breaking heat, which could be a part of climate change," Taft said on "CBS Mornings." "Just the difference and the clash in air masses...it was really just a perfect set up for such a big storm." 

On Saturday, President Biden said that the intensity of the weather "has some impact as a consequence of the warming of the planet," and called on the Environmental Protection Agency to look at climate change's role in the catastrophe. 

But when it comes to tornadoes, it's not quite that simple, experts tell CBS News.

Despite the historic standing of Friday's tornadoes, Gensini said "we can't tell right now" if it was a direct result of climate change.

"We don't have the attribution science to say with some degree of certainty that last Friday evening's tornadoes were a component of climate change," he said. "But what we can say is when you start to look at the aggregate...that these tornadoes are sort of changing and not only when they occur — getting a little bit further eastward — but changing in their intensity." 

In 2018, Gensini and Harold Brooks, a senior research scientist with the National Oceanographic and Atmospheric Administration's Severe Storms Laboratory, published a study that found the zone of the country most susceptible to tornadoes, known as "Tornado Alley," may be shifting eastward. The researchers warned that the shift puts more people at risk because the areas are more densely populated. 

What researchers have seen, Brooks said, is that tornadoes have become much more variable in their intensity, and will likely continue to do so, making it difficult to pinpoint when more disastrous storms, like EF-4 or EF-5 tornadoes, will take place.

The uncertainty of tornado prediction

Right now, Brooks said that researchers expect that some of the elements that create conditions for tornadoes will be impacted by climate change, such as temperature, but they can't predict exact atmospheric conditions in the future, an essential component in anticipating specific tornado events. 

"Tornadoes are a lot harder to connect with global warming, and the effects on them," he said. "Some of the ingredients, like the warm moist air, is probably going to increase in intensity, and that's favorable for tornadoes. The change of the wind with height, on average, is probably going to decrease." 

Meteorologist and climate scientist John Allen is among researchers using climate models to try and better predict the broader future of tornadoes with climate change. Doing so, however, is a challenge, he said, because it is already difficult to predict storms as they happen now. 

"One of the things we struggle with now is, is a storm going to initiate? If I have the environment that is right to produce tornadoes, is there a storm that's going to initiate and where is it going to initiate," he said. "We don't predict that well." 

What they've seen so far, Allen told CBS News, is that future environmental factors may result in fewer storms and a different tornado season than what the U.S. is used to. Instead of people bracing for these storms from March through June, they could potentially see most tornadoes developing around the times that seasons change. 

They have also seen that rising global temperatures could make it more difficult for storms to form, decreasing their frequency. However, it could make the ones that do form, "go off more with a bang."

"The idea here is basically like a lid on a pot," Allen said, equating the heat to being the lid. " ...And storms form when they break through that lid. But if you keep on increasing the strength of the lid, you weld it to the pot, that lid gets harder and harder to break, and so the energy has to be stronger and stronger from the surface to do so." 

Altering coastlines and climate change migration

The United Nations and other entities have repeatedly warned that global warming will undoubtedly lead to increased flooding and stronger hurricanes, which are expected to change what the nation's coastlines will look like. Ocean temperatures are anticipated to somewhat rise in the process, particularly in the Gulf of Mexico, and Allen told CBS News that "there's definitely some indicators that sort of suggest that's something we need to worry about." 

"There's been some studies that have explored, if you take a known big tornado event and drop it in a climate change environment, what happens. And what they found was that there was at least some increase in intensity of that particular event," he told CBS News. "But I think that there's still work that needs to be done." 

And because of the expected surge in coastal flooding and hurricanes, it's also anticipated that many who live along the East Coast will be forced to move inland, including into areas hardest-hit by violent tornadoes.

"That's the worst thing about the shift towards the East of tornado frequency. ... If you look at the change in population since the 1950s, the Southeast is where the growth is seen in the United States, it's not pretty much anywhere else," Allen said. "...As that population continues to increase, the likelihood of any tornadoes that occur, impacting people is going to increase." 

Brooks said that with more people in these areas, which typically have homes not built to withstand strong tornadoes, it's likely that the death toll of such storms will be higher. 

"This little bit of change in where tornadoes are occurring means we're putting more tornadoes potentially into places where there actually are people," Brooks told CBS News. "A tornado in rural Tennessee, rural Alabama has a much greater chance of killing people than a tornado in rural Kansas does."

And even if tornadoes do not get worse or more frequent because of climate change, Allen said, the impact of a single one could still be disastrous. 

"All that climate change is going to do is change the odds ... but realistically, odds don't matter. One tornado is more than enough for any one person or any one area that's going to impact your life and your livelihood," Allen said. "...The strongest tornado isn't necessarily a great indicator of the impact on people's lives."  

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