More than 4 million homes face substantial risk of expensive flood damage, a research organization says. Communities where flood insurance is already unaffordable face potentially catastrophic damage.

Transcript

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More than 4 million homes in the United States are at risk of suffering major flood damage - that's according to new data released today. Climate change is driving a lot of that flooding, and poorer people stand to lose the most. NPR's Rebecca Hersher reports.

REBECCA HERSHER, BYLINE: Pastor Aaron Trigg cannot say enough good things about Rainelle, W.V., where he used to live.

AARON TRIGG: People were just happy and joyous and had a lot of expectation for the future.

HERSHER: Rainelle is small. About 1,500 people live there. It's got a school and a grocery store and a couple stoplights. And it's in a steep valley with a creek running through it. In the summer of 2016, there was a lot of rain, and the creek started rising.

TRIGG: And you could hear the water up in the mountains crashing trees. And next thing you know, it was at our waist.

HERSHER: It was evening. Trigg's house was already underwater, so he took shelter on the second floor of his neighbor's house.

TRIGG: But you could hear people screaming and hollering for help. It was a real restless night, a real - just no peace at all. I did a lot of praying that night.

HERSHER: Trigg was rescued by boat in the morning. In all, at least 23 people in West Virginia died in the floods. More than a thousand homes were destroyed. Rainelle was decimated. It's one of hundreds of small towns across the country where climate-driven flooding is an existential threat.

New data from the First Street Foundation, a climate risk nonprofit, shows that more than 4 million homes are at risk for expensive flood damage. They're concentrated on the coasts and in Appalachia, although there are hot spots across the country. And the homeowners who will be hit the hardest are those who can't afford flood insurance. Matthew Eby is the executive director of the First Street Foundation.

MATTHEW EBY: In America, flood insurance for the vast majority of the population is provided through FEMA's National Flood Insurance Program.

HERSHER: And that flood insurance doesn't cost the right amount - that's according to FEMA. Every month, homeowners who have flood insurance pay a monthly premium. But those monthly premiums don't even come close to covering the actual cost of flood damage from most houses. The government always has to pick up the tab, which is why the National Flood Insurance Program has racked up more than $36 billion in debt, and it's one reason that developers keep building homes in dangerous places.

To help fix all of that, FEMA is going to start raising the price of flood insurance later this year. But to actually keep up with the cost of climate change, the new data suggests that flood insurance rates would need to more than quadruple in the next 30 years, which would put flood insurance out of reach for many, if not most, families.

EBY: So there'll be a ton of properties without policies that are just waiting for that unfortunate event to happen. And then we're going to see a lot of actual economic pain because they won't have the ability to then fix the home.

HERSHER: FEMA says the group's analysis is, quote, "premature" because FEMA hasn't released the full details of its new pricing scheme. But what research makes clear is that when large numbers of people don't have insurance or savings after a disaster, the effects can ripple through a community. That's exactly what happened in Rainelle after the 2016 flood. Pastor Aaron Trigg was getting calls late at night from his congregants.

TRIGG: The way I could say it is they were hopeless because they - a lot of people in Rainelle were poor, and they didn't have insurance. They didn't have any way to have any backup plan.

HERSHER: He says a lot of people left town. Trigg stuck around for a few years before he, too, moved away for a new job. A lot of homes were never rebuilt. Today, entire blocks of Main Street are empty of businesses. John Wyatt is a city councilman and a pastor and a musician, flood survivor and the owner of a music store in Rainelle. He's also running for mayor. And like any good mayoral candidate, he's a booster for his town.

JOHN WYATT: We're a bona fide Appalachian community, and we have a lot to offer.

HERSHER: For example, he'd like to see Rainelle host an Appalachian music festival. There are some barriers. The only motel in town has been closed since the flood nearly five years ago. But Wyatt has a vision of Rainelle as a tourist destination - maybe, if the water cooperates.

WYATT: If we ever have another flood like that, I can't see - I just really cannot see our town surviving. I mean, it just...

HERSHER: He trails off and picks up his guitar.

(SOUNDBITE OF ACOUSTIC GUITAR)

WYATT: (Vocalizing). Transcript provided by NPR, Copyright NPR.