Short Wave - The supertree shielding coastlines and storing carbon

Episode Date: May 22, 2026

Coastal fishing communities around the world are struggling with declining fish stocks. That’s because of climate change, environmental degradation and overfishing. But one tree – the humble mangrove – has a superpower that’s supporting healthy fisheries in many parts of the world. The majority of fishes we eat worldwide are supported by mangroves: Their roots serve as a nursery for baby fish. So, today on the show, two reporters travel to Cambodia, where they discover why a local fishing solution now plays a crucial role in slowing global warming. Read more about Rebecca Hersher and Ryan Kellman’s journey here (and check out their incredible photos). Interested in more climate science? Email us your question at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey everyone, Emily Kwong here, and today we have a story of good news about climate change. And as part of NPR's Climate Solutions Week, two of my colleagues are here to tell that story. Ryan Kelman and Rebecca Hersher. Hi. Hi. All right, where are we going today? This story starts in Cambodia.

And Cambodia, as you may know, experienced horrific political violence in the 1970s. under a group called the Khmer Rouge. Yeah, I'm familiar with this history during the Cambodian genocide. It's estimated that 1.7 million people died. It completely changed the course of history for that country. Yeah. And even after the regime fell in 1979,

things were still really hard for those who survived because the Khmer Rouge also destroyed the country's economy. And that's where this story really begins. in those years just after the Khmer Rouge's reign, the late 1970s and into the 1980s. So, yeah, that's the period we were really interested in when we traveled to Cambodia for a reporting trip recently. And we spent a couple days with a group of people who lived through that time after the Khmer Rouge fell when the Cambodian economy was in Tatters. And we wanted to learn from them how their experiences led to them becoming global leaders in addressing climate change.

Wow. So from the aftermath of a genocide to the front lines of solving climate change, that's pretty incredible. Yeah, it's a wild tale. And it all hinges on one type of tree. Today on the show, how one tree saved a community and how that same tree is helping all of us right now. You're listening to Shortwave, the science podcast from NPR. Okay, Rebecca and Ryan, this story begins post-regime change in the 70s and 80s. We're in Cambodia. The economy is terrible. What are people doing to cope? They are just trying to survive. Like anyone, they just need basics, food and fuel. Both are in short supply. When we visited, we actually spent a day with Kiyosat.

He was in his 20s when the Khmer Rouge fell. He was living in a small fishing village called Co-Kresna. It's right next to the ocean. He says people had nothing. And so people in town cut down local mangrove trees to burn and make into charcoal, he says, to cook with. So at the time, it maybe didn't really seem. like that big of a deal. The folks were obviously dealing with other problems. And, you know, mangroves are sort of, let's say, innocuous looking. Not to me. They look kind of magical because

the roots are aerial. They're like floating above the water. But I know they're like super common in this part of the world. Yeah, totally. I mean, they just look like shrubs. They're, they're densely packed with this tangled mess of a root system that happens to be specially adapted to live in saltwater. And so, That also means the areas where you generally find mangroves are sort of like tidal marshy. I love them. But they're more swampy areas than, you know, sandy beaches. So for some people, they might not look all that amazing.

But no matter what you think they look like, these trees are amazing. They basically have superpowers. Three superpowers, in fact, that we want to talk about today. Super trees with three superpowers. Let's hear them first up, supermangrove power. number one is it's trapping carbon. Bebubo bough, bough. Yeah, so all trees trap some carbon.

You know, trees take in carbon dioxide to grow. They lock that CO2 away in their trunks and their leaves, and it's released when the tree dies and decomposes. Grateful to them. I know. So cool. Trees, amazing. But mangrove forests trap way more carbon than other forests. They can store up to four times as much carbon as other types of forests once study found.

And that's mostly because the stuff that falls into the water and gets trapped around mangrove roots decomposes really slowly. So all that carbon is trapped in the mangrove forest for a really long time. I knew I liked those roots. So it means less carbon dioxide is escaping into the atmosphere where it would contribute to global warming because it's like holding up in those, it's holding up in those roots. Exactly. So mangrove forests are basically punching way above their weight when it comes to trapping planet warming gases before they can make it into the atmosphere. And every mangrove that gets cut down must make climate change worse. Yeah.

Okay, what is mangrove superpower number two? Wave attenuation. What is that? What is that? Everyone's favorite. I don't know what that is. It sounds really cool, though. It is very cool.

The intricate root system, we were talking about earlier. Yeah. holds tight to the mud and the soil around the trees. So they reduce erosion and absorb the power of storm surges. Oh, yeah. So they end up protecting the inland areas. from flooding. That's amazing.

One study found that a forest about a football field wide can actually reduce wave height by up to 66%. So basically, if you have 100 yards of mangrove between you and the ocean during a storm, the waves that actually make it to your house are going to be a lot smaller. Huge. And that kind of protection is really only growing in importance

because climate change is making powerful storms more likely. These trees are climate superhero. They store more carbon, they protect from erosion. What is their third and last superpower? They are amazing for fish. Yeah, fish love to lay their eggs around mangrove roots. So I called up a scientist to talk about this one. Her name is Radica Bargaba Gajre, and she's a coastal geographer and a mangrove expert

at the National University of Singapore. Their roots are very good nurseries for baby fishes or even for mother fishes to go and lay their eggs. Majority of the fishes that we eat are supported by mangroves during their early childhood reproduction stages. I just want to make sure you caught that. The majority of the fish we eat start in mangrove fruits. In the world? In the world. These trees are clearly exceptional. So, I mean, thinking about the history you're describing earlier, when people in Cambodia were cutting them down in the 80s for fuel, for warmth to survive, what happened to the local environment. Without the trees to do all that they do and provide that nursery for the fish,

the ecosystem essentially collapsed. The shrimp, sardines, bream, crabs, the whole fish population, the sea life in general was decimated. So without the fish or anything else to catch, the nearby villages were also in big trouble. So as a result, some folks left to go find a life somewhere else and, you know, the people that stay just had to struggle through these really difficult times. Yeah. Okay. Yeah, and it's not just Co-Kresna where people cut down mangrove trees. You know, a lot of people around the world want to live on the coast. There's a lot of pressure to clear-cut these swampy mangrove forests to make way for humans. Half of mangrove forests are at risk of collapse by 2050, according to the UN. But, Emily, this is the part where this turns into a good news,

story. It better because that's what you've been promising. So over the last three decades, there's been a massive effort by scientists and international ecological protection groups to spread awareness about the importance of these threatened mangroves. And they've really made an impact. And Kiyosat experienced it firsthand. We started to educate each other, he says. So, you know, they're spreading the knowledge about not cutting the trees down. Yeah, and since 2003, Kiyos village and a neighboring village, they've worked together to protect more than 145 acres of mangrove forest along that section of Cambodia's coastline. And in the last two years, they've actually planted more than 2,000

mangrove saplings. And similar efforts are happening in other parts of the world. It's really adding up to something. Net loss of mangroves decreased by 44% in the period between 2010. in 2020, relative to the previous decade, according to a 2023 U.N. analysis. Oh, so you're saying that the loss of mangrove trees has slowed down considerably. Yeah, the world's mangroves are headed in the right direction. And if we can keep going, it would be really good news because maybe the total amount of mangrove forests on Earth could actually have a net increase eventually. Yeah.

Rebecca and I got to see this restored and protective mangrove forest in Cambodia near Co. Kresna. Ah, amazing. So, Mr. Satt was our guide, and it was amazing. Especially for me, I've basically been dreaming about seeing these mangroves in real life for so long, and it was delightful. These little birds were, you know, flittering from tree to tree and across the mangrove creeks.

Eagrits were, you know, sort of bright and white in the sunlight and prowling for fish below them. And we could even hear this really loud, strange popping noise, which we were told was actually the sound of a particular snail. We got to meet fishermen. Some were standing waist deep, pulling up mats full of fish. Others were motoring out to find their catch farther offshore. The whole place just felt alive. Wow. The ecosystems rebounding. Fishing is happening. I mean, Clearly, this mangrove restoration has been instrumental to this one community in Cambodia. But thinking beyond them, it sounds like their efforts could also help address climate change everywhere, right? Because these trees are so good at locking in carbon.

Yeah, totally. And we actually asked folks there about, you know, to what extent that larger impact is siliant to them, whether they think about it. You know, for average fishermen, maybe that's not the main motivator, obviously. But we found that for those in leadership positions and for younger people, it's definitely part of the equation. Kiyosat is now the chief of Kho Kresna, and he's definitely aware of how his work connects to climate change. And we also asked his son, Chian, what he thinks. And he was more forceful. He told us, we are helping the whole world.

And he's totally right. Some magical trees being taken care of by some pretty cool people. Thank you so much, Ryan and Rebecca, for sharing this story all the way from Cambodia. Thank you, Emily. Thanks so much. If you liked this episode, share it with a friend. It really helps us out. And if you want to check out more stories from Climate Solutions Week, take a look at our show notes.

We'll link to the series page. This episode was produced by Rachel Carlson and edited by Nila Banerjee and our showrunner, Rebecca Ramirez. Tyler Jones checked the facts. Jimmy Keely was the audio engineer. I'm Emily Kwong. Thank you for listening to Shortwave from NPR. See you next time.