JUANA SUMMERS, HOST:
In the Midwest, nearly a week of severe storms has caused heavy flooding, particularly in Indiana and Ohio. Roads have been washed out. Homes and buildings have been damaged. The Midwest is seeing these floods more often. And NPR's Lauren Sommer is here with more on that. Hey.
LAUREN SOMMER, BYLINE: Hey, Juana.
SUMMERS: So, I mean, Lauren, I grew up in the Midwest, so I know that the region is no stranger to heavy rain, even to major floods. But how is the region's flood risk changing now?
SOMMER: Yeah, so the big change isn't really the amount of rain that the Midwest is getting over a year. It's how fast it's getting that rain. You know, basically, extreme storms are producing more rain than they used to because of climate change. I spoke to Beth Hall, the Indiana state climatologist, about what happens with rainfall like that.
BETH HALL: All of a sudden, when it comes, it's coming down so hard and intensity and so much moisture that it really - the ground is not prepared to take it in because that much water just cannot be absorbed locally.
SOMMER: And, you know, the rainfall data really shows this. According to the National Climate Assessment, the most extreme storms in the Great Lakes region are now dropping 45% more rain than they did, going back to the 1950s.
SUMMERS: Wow. Do researchers know why rainfall is getting so much heavier from these storms?
SOMMER: Yeah. So one of the key factors here is just what's happening in the atmosphere. The climate is warmer, and warmer air can actually hold more moisture. It holds more water vapor. So these storms just have more to work with, and they produce more rain. And this isn't just happening in the Midwest. You know, extreme rain is getting worse in New England and the South as well.
SUMMERS: Right. The climate is still heating up, so how much worse are researchers expecting extreme rainfall to be in the future?
SOMMER: You know, it depends on how much hotter the atmosphere gets based on how many - how much fossil fuels are burned. But in the Midwest, extreme rain could get 20- to 30% worse, according to the National Climate Assessment, and that's if the planet heats up by 2 degrees Celsius, which is about 3 1/2 Fahrenheit. That obviously causes river flooding, right? That impacts communities. But it also causes flooding in places that are not close to rivers. I mean, you've probably seen that, right?
SUMMERS: Yeah.
SOMMER: You know, the road, the intersection, it gets full of water. All our infrastructure is only built to handle a certain amount of rain, and it just gets overwhelmed when there's more than that.
SUMMERS: So, Lauren, what's being done in the Midwest or really, I guess, anywhere in the United States to prepare for a future where we're seeing and experiencing more extreme rain?
SOMMER: Yeah, so climate experts say the key thing is to build infrastructure that can handle that much water, and that really comes down to what information engineers have to plan with. Indiana climatologist Beth Hall told me it doesn't work for cities to use these old rainfall records that just show how storms used to be.
HALL: We need to update those perhaps a little bit more often than we used to in the past because what was a hundred-year event 20 years ago might now be a 50-year event. It's important that we have those updated numbers so that we can understand what to expect.
SOMMER: And, you know, there is a big effort underway right now by the federal government to do that and to get cities some better information to plan with. The National Oceanic and Atmospheric Administration is updating all the rainfall data for the whole country. It's known as Atlas 15, and their kind of preliminary version is expected by September. And it'll really reflect how storms have already gotten worse and will keep getting worse with climate change so local governments can build their infrastructure to handle that. It is something that some cities and states are starting to do. North Carolina's a good example, which is, after Hurricane Helene, they've actually started to build roads to handle a future with more extreme storms, with climate change. It's more expensive to build that way, but climate experts say it's cheaper to spend that money now than, you know, just have to rebuild it again when it's damaged.
SUMMERS: NPR's Lauren Sommer, thank you.
SOMMER: Yeah, thanks so much.
(SOUNDBITE OF HERMANOS GUTIERREZ'S "IT'S ALL IN YOUR MIND") Transcript provided by NPR, Copyright NPR.
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