Major River Flooding, Outbreaks Of Tornadoes: Is This What Climate Change Looks Like?

This week the central U.S. has flooded and experienced deadly and damaging tornadoes. When it comes to what Americans could see more of due to climate change — the links are present, but complicated.

AUDIE CORNISH, HOST:

Much of the central U.S. is underwater this week. Four major rivers in the middle of the country are at various stages of flooding. There have also been multiple outbreaks of deadly and damaging tornadoes. It all begs the question, is this what climate change looks like?

Joining us from Arkansas, where the Arkansas River is flooding, is NPR's science reporter Rebecca Hersher. And Becky, first just describe where you are, what you're seeing.

REBECCA HERSHER, BYLINE: Well, I'm sitting right next to the Arkansas River, and the water here is so powerful. Like, you can hear in the background the waves are crashing as if it's on a beach. It's actually a public park. And this is a big, wide, flat river. It usually has a lot of barge traffic. And when it floods, the water gets high. But really, what it does is it gets wide. It spreads out as far as it can.

And in a place this flat, that means it floods your home all the way up to the rafters in some places I've been. And it floods roads, which is a problem because even if you live and you work on high ground, your path to work, to school might be blocked by high water. So the governor of Arkansas says that's going to cost the state $23 million a day.

CORNISH: So taking a step back, this question about climate change - is this flooding happening because of climate change?

HERSHER: Well, in short, yes, sort of. This river is high because of extreme rain. So when it rains here now, it rains more than it used to in the past. And that's in line with what we would see under climate change conditions. The National Climate Assessment predicts that when it rains, it's going to rain more in the future because warmer air can hold more moisture.

And actually, already, we're seeing that in the Midwest and along the East Coast. Sometimes 50% more rain is falling in a single rain event than used to earlier this century. I hear a lot of flood plain managers use the word unprecedented. It's the kind of rain that we just haven't seen in the past.

CORNISH: What does this mean for places in the Midwest and South?

HERSHER: Well, there's a lot of stress on infrastructure that really was not built to hold this. So all along the river, along rivers like this, there are levees. And in places like this, they were actually built to make sure there's enough water for barges to ship things down the river. They really were not designed to hold back floodwater at all, and they really weren't designed to hold back this amount of water for this long.

The water has been high for days. It's going to be high for weeks more. So you can imagine it's really nerve-wracking when your whole livelihood is behind a pile of sand that was not even designed to keep it safe in the first place from something like this.

CORNISH: What are emergency officials doing?

HERSHER: Well, it's really hard for emergency officials here. I've talked to a handful who have said that because this is such a slow-moving disaster - you know, multiple rain events, the river rising relatively slowly over the course of weeks - it's hard to convince people to leave sometimes.

For example, I met a man who had evacuated with his four kids. His neighborhood was under threat from the river. But he can't get his sister-in-law to evacuate because she says, well, this has never happened before; why would it happen this time? And now the river has cut off access to the neighborhood. So even though her house isn't flooded, she can't get out.

CORNISH: And then there's the hurricane season that starts in the Atlantic tomorrow.

HERSHER: Yeah. And of course, hurricanes are changing as the Earth warms. This is sort of the classic, archetypal climate-affected weather system. They're getting larger and wetter. They're dropping more rain. Think Hurricane Harvey in Texas in 2017. Think Hurricane Florence in the Carolinas last year. This year, the Weather Service predicts a normal year. I'm putting that in scare quotes. That means two to four major hurricanes. But it only takes one of those hitting the U.S. to do a lot of damage, so it all adds up to just an enormous amount of flood danger for a lot of Americans.

CORNISH: That's NPR science reporter Rebecca Hersher. Becky, thank you.

HERSHER: Thanks.

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