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Because of climate change, inland flooding is becoming more common

ASMA KHALID, HOST:

Climate change is making these types of disasters more and more common. I spoke with Rebecca Hersher from NPR's climate team, and she explained why destructive flooding is happening far from the coastlines.

REBECCA HERSHER, BYLINE: There are many ways that climate change can cause floods. Coastal floods get a lot of attention, especially when they happen during a hurricane. But actually, inland flooding is more common. And the kind of devastating heavy rain that we've seen this week is something that climate scientists have predicted for many decades - that, as humans keep burning fossil fuels, the atmosphere gets hotter, the air holds more moisture and so, when it rains, it rains harder.

KHALID: And has that turned out to be true?

HERSHER: Yeah, the climate models are correct. And actually scientists can observe it in real time now, which is pretty scary. So heavy rain has increased all over the U.S. And in the southeastern U.S., including in Kentucky, it's increased by almost a third.

KHALID: Wow.

HERSHER: Now, that might not sound like a lot, but an extra inch of rain, if you think about it - if that falls in a short period of time, that is how you get a flash flood.

KHALID: So explain that because I do think it is shocking to see some of the damage that all of this rain has caused, particularly in Kentucky, as you mentioned.

HERSHER: Yeah. The danger and the damage comes from moving water, and that can happen in two ways. So first, when a lot of rain is falling in a short period of time, the water doesn't have anywhere to go. It can't soak into the ground, especially if the ground is already saturated. So that causes the water to pool on the surface. And then if there's a hill - even a really small hill, one that you might not even notice - all that water starts to roll downhill. It gathers speed, it gathers power, it can pick up debris. And that is a flash flood. It's really dangerous. It can carry away cars, it can carry away houses, and it can kill people.

KHALID: So how common is that type of flooding? You know, you said it is getting more frequent at this point.

HERSHER: Yeah. And unfortunately, these kinds of floods, they're so frequent that they're a part of life in some places. So there are towns and cities in the U.S. where flash floods happen every year or every other year. That's true in parts of southeast Texas and Louisiana, parts of the Midwest and Appalachia, where this week's floods happened. For example, last summer, there was a flash flood that killed nearly two dozen people in Tennessee. That same area was hit by very heavy rain this year. And it's important to say, this is not just a U.S. problem. It's happening outside the U.S. as well. So heavy rain has caused deadly flash floods in Germany and Belgium, South Africa, India, China and Australia. And that's just in the last year.

KHALID: So what can be done to warn people when a flood is about to happen?

HERSHER: Well, that's actually something the National Weather Service is really focused on. So local offices are watching for signs of heavy rain and then trying to warn people as early as possible if a flash flood is likely. And that's really important because so many of us get our weather warnings now directly on our phones, right? Your phone will flash and you'll get an alert saying there's a flash flood warning for your area. And if that happens, you need to take it extremely seriously. And particularly, don't drive on flooded roads. It's one of the main ways that people die in flash floods. Their cars just get swept away.

KHALID: So, I mean, I've got to wonder, are there ways to make these floods less dangerous, or do we all sort of have to learn to live with this new reality?

HERSHER: There are lots of ways to make them less dangerous. So basically, you slow the water down, give it safe places to go. For example, have less pavement so the water can soak into the ground. You can build retention ponds - you know, those low marshy areas for excess water to collect.

KHALID: Right.

HERSHER: And in cities, you can make the pipes bigger. So a lot of U.S. cities were built 50, even 100 years ago. The storm water systems are not built for the heavy rain of today. It's expensive to make those pipes larger, but it's really important if you want to prevent streets from turning into rivers.

KHALID: Rebecca Hersher from NPR's climate team, thanks, as always.

HERSHER: Thanks.

(SOUNDBITE OF SEAS OF YEARS' "MESOPELAGIC TRANSMISSIONS") Transcript provided by NPR, Copyright NPR.

Asma Khalid is a White House correspondent for NPR. She also co-hosts The NPR Politics Podcast.
Rebecca Hersher (she/her) is a reporter on NPR's Science Desk, where she reports on outbreaks, natural disasters, and environmental and health research. Since coming to NPR in 2011, she has covered the Ebola outbreak in West Africa, embedded with the Afghan army after the American combat mission ended, and reported on floods and hurricanes in the U.S. She's also reported on research about puppies. Before her work on the Science Desk, she was a producer for NPR's Weekend All Things Considered in Los Angeles.