Trotwood, Ohio – Three years ago, Derrick Stephens and his family experienced one of the most traumatic nights of their lives when a powerful tornado swept through their Ohio neighborhood.
The tornado, packing winds of around 270 kilometers per hour (268 miles per hour), destroyed much of the family home in the western town of Trotwood.
“We lost 90% of our belongings and 75% of our house,” Stephens told Al Jazeera.
“After it hit, I walked outside and could see the tornado moving away. There was this green flash all around. It was the weirdest thing.
The storm was part of a larger outbreak of dozens of significant tornadoes across the United States in May 2019. They leveled homes, trees and businesses, damaging about 500 homes in Trotwood alone. The city’s mayor said it could take a decade to recover from the damage estimated at $18 million. Miraculously, only two deaths have been attributed to the series of tornadoes.
For decades, the most active tornado area in the United States – known as Tornado Alley – has been located more than 1,000 km west of Trotwood, mostly in the states of Texas, Oklahoma, Kansas, Nebraska and South Dakota. But the danger zone seems to be shifting, as evidenced recently by the devastating tornadoes in Michigan and Minnesota.
Indeed, a growing bank of research finds that highly destructive tornado activity is moving eastward into states with denser metropolitan populations, exposing millions more people to severe weather.
“[The shift to the east] seems to be a consistent trend in the modeling… Warmer temperatures, more humidity from the Gulf of Mexico seems to support this,” Perry Samson, professor of atmospheric sciences at the University of Michigan, told Al Jazeera.
As more people move into tornado-prone areas, driving housing and infrastructure development, the potential threat intensifies, Samson said.
“It’s more this factor that worries us the most; there will be more impact because there is more to be impacted,” he said.
Equally worrisome to millions of Americans, violent tornadoes, which have traditionally occurred most often in spring and summer in the Northern Hemisphere, are becoming an increasing threat throughout the year.
Last December, dozens of people died when a tornado packing winds of 310 km/h (193 mph) hit Kentucky, devastating towns as it traveled a path of more than 260 km (160 miles) , in what experts say is an extremely rare occurrence.
“This storm moved in a favorable environment [for tornado activity] for several hours. It’s something that doesn’t normally happen often in December,” John Allen, an associate professor of meteorology at Central Michigan University, told Al Jazeera.
As for the eastward move of Tornado Alley, most of the incidents “actually come from the winter period,” he added.
Tornadoes form in the presence of severe thunderstorms, which usually occur when warm, moist air meets cold, dry air. Significant changes in wind speed or direction can then lead to the formation of tornadoes.
While climate change has led to more extreme weather events around the world, there is no definitive consensus among scientists on its role in shifting tornado activity.
A warmer, wetter climate could play a role in various types of extreme weather events. But when it comes to tornadoes, it has been difficult to identify long-term trends. This is due both to changes in weather monitoring systems and the increasing ease with which researchers and members of the public can now detect and report tornadoes.
“We can discern whether a storm is going to produce the types of conditions in which tornadoes occur,” said Samson, whose department runs a website that maps tornadoes.
“But that’s not enough to be able to say, with certainty, whether tornadoes are changing or will change in the future.”
Last December, after the devastation in Kentucky, the White House said it would task the Federal Environmental Protection Agency (EPA) with investigating the role climate change may have played in the killer tornadoes.
Al Jazeera contacted the EPA for an update on the status of the investigation, but did not receive a response.
For Stephens, who only returned to his Trotwood home last summer, the rebuilding process has been difficult – and he is convinced climate change played a part in the disaster.
“I think the damage started with the Industrial Revolution and the wars that have happened since then that created the demand for industrial products like gas and oil,” Stephens said.
“Before the 1960s, there was no environmental protection agency, no pollution standards,” he said.
“Unfortunately, we all know that humans in general don’t really care.”