Do you want the good or bad news on tornadoes and hurricanes?

By Mark Gongloff

If the Car Crash Fairy offered you a deal that would lower your odds of getting in a car accident, but the trade-off was that any accidents you did get into would be far more likely to injure or kill you, you probably wouldn’t take that deal. But that might be the bargain we have made with climate change and two of the most destructive natural disasters.

Many of the heat waves, droughts and floods wracking the planet have clearly been made more likely by warming. The jury is still out on whether tornadoes and hurricanes will similarly become more frequent. They might even happen less often, at least in some places. But the ones that do occur could be more destructive, raising risks for everyone from insurers to urban planners.

People in the Midwest facing yet another onslaught of tornadoes this week could be forgiven for thinking there have never been more of them. Consider Indiana, for example, suffering its fifth twister attack of 2024 after one of the state’s busiest years on record. But, in fact, tornadoes seem to happen in Indiana about as often now as they did in, say, the 1970s.

This might seem counterintuitive. The supercell thunderstorms that breed tornadoes thrive on heat, moisture and instability in the air, something weather nerds call CAPE, or convective available potential energy. And climate change is certainly generating plenty of that. But these storms also need “wind shear,” a change in wind speed and direction at different altitudes. While global warming creates more CAPE, it also creates less wind shear.

In some places and times, warming’s CAPE effect will outweigh its wind-shear effect, producing more tornadoes. In other times and places, the opposite will happen. Good luck trying to model it; tornadoes are hyperlocal events that chaotically pop in and out of existence like virtual particles or TikTok dances.

A 2021 study by researchers at Columbia University and Central Michigan University suggested that every 1 degree Celsius of warming would make tornado-friendly conditions increase by 5% to 20%, though the actual incidence of severe weather would increase by a little less. The planet has warmed by about 1.3C above preindustrial averages so far. Maybe a world of 2.7C warming will have noticeably more supercell storms and other severe weather, including damaging winds and hail.

And a new study from researchers at Iowa State University and Lawrence Berkeley National Laboratory suggests that, as the climate warms, tornadoes will increasingly be included in the package deal of misery delivered by hurricanes, along with floods, storm surge and high winds.

Again, though, the jury is out. A couple of years back, scientists did notice a trend of fewer days with tornadoes, but many more tornadoes hitting all at once, in clusters, when conditions were right. And they generally expect that the Tornado Alley that cuts through the middle of the US will shift eastward over time and that supercell storms will happen earlier in the year as the planet warms.

That may sound like a wash, but as tornadoes leave the great wide open of the Plains, they will encroach on places where more people live, often in mobile homes and other structures that aren’t prepared for them. The net effect is that the number of severe US storms inflicting at least $1 billion in damage has soared in recent years, setting a record in 2023, according to the National Oceanic and Atmospheric Administration.

Hurricanes are a little easier to predict than tornadoes, and climate models suggest global warming might actually make them happen less often. Despite all the heating we’ve experienced so far, the same number of hurricanes make landfall in the US today as 125 years ago, according to NASA.

That’s where the good news ends. As Texas A&M University climate scientist Andrew Dessler pointed out in a recent Substack post, hotter air and water — along with the aforementioned dampening of wind shear — mean the hurricanes that do form will be far more intense and destructive. Rising sea levels will also increase storm surge, and don’t forget about those hurricane-spawned tornadoes (hurrinadoes?). As with tornadoes, the end result could be more deaths and injuries and more monetary damage and losses for insurers, even if hurricanes are fewer in number.

The first lesson here is that we must stop making the climate even more chaotic by burning fossil fuels and pumping greenhouse gases into the atmosphere as quickly as possible. Meanwhile, businesses and homeowners who might think they’re not in harm’s way should consider the possibility that the harm will come to find them. Policymakers need to help vulnerable people prepare for a potentially more dangerous future and ensure that infrastructure and housing can better withstand whatever nature brings. When it comes to disasters, as with car accidents, quantity is far less important than quality.