The supertree shielding coastlines and storing carbon

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 https://www.npr.org/2026/03/27/nx-s1-5671057/mangrove-fisheries-climate-change-cambodia 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 [email protected] mailto:[email protected]. Listen 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 http://plus.npr.org/shortwave. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:15Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:21Emily Kwong?

  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.

• 0:35Speaker 02

  Hi.

• 0:35Emily Kwong?

  All right. Where are we going today?

• 0:37Speaker 03

  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.

• 0:49Emily Kwong?

  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.

• 0:58Speaker 03

  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.

• 1:21Speaker 02

  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 of 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.

• 1:44Emily Kwong?

  Wow. So from the aftermath of a genocide to the front lines of solving climate change? That is, that's pretty incredible.

• 1:51Speaker 03

  Yeah, it's a wild tale. And it all hinges on one type of tree.

• 1:57Emily Kwong?

  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 Short Wave, the science podcast from NPR.

• 2:21Speaker 04

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• 2:25Speaker 05

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• 3:28Emily Kwong?

  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?

• 3:40Speaker 02

  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 Kyo Sat. He was in his 20s when the Khmer Rouge fell. He was living in a small fishing village called Koh Presna. It's right next to the ocean.

• 4:05Speaker 02

  He says people had nothing.

• 4:13Speaker 02

  And so people in town cut down local mangrove trees to burn and make into charcoal, he says, to cook with.

• 4:21Speaker 03

  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.

• 4:34Emily Kwong?

  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.

• 4:41Speaker 03

  Yeah, totally. I mean, they just look like shrubs. They're densely packed with this sort of tangled mess of a root system that happens to be specially adapted to live in saltwater.

• 4:52Emily Kwong?

  Yeah.

• 4:53Speaker 03

  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.

• 5:19Emily Kwong?

  Super trees with three superpowers. Um, let's hear them. First up, super mangrove power number one is?

• 5:25Speaker 02

  It's trapping carbon.

• 5:30Speaker 02

  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.

• 5:40Emily Kwong?

  Oh, grateful to them.

• 5:41Speaker 02

  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, one 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.

• 6:06Emily Kwong?

  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.

• 6:16Speaker 02

  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.

• 6:24Emily Kwong?

  And every mangrove that gets cut down must make climate change worse.

• 6:28Speaker 02

  Yeah.

• 6:29Emily Kwong?

  Okay, what is mangrove superpower number two?

• 6:32Speaker 03

  Wave attenuation.

• 6:33Emily Kwong?

  What is that?

• 6:34Speaker 02

  What is that?

• 6:35Speaker 03

  Everyone's favorite.

• 6:36Emily Kwong?

  I don't know what that is. It sounds really cool, though.

• 6:38Speaker 03

  It is very cool. The intricate root system we were talking about earlier

• 6:42Emily Kwong?

  Yeah.

• 6:42Speaker 03

  holds tight to the mud in the soil around the trees. So they reduce erosion and absorb the power of storm surges.

• 6:51Emily Kwong?

  Oh, yeah.

• 6:52Speaker 03

  So they end up protecting the inland areas from flooding.

• 6:55Emily Kwong?

  That's amazing.

• 6:56Speaker 03

  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.

• 7:13Emily Kwong?

  Huge.

• 7:14Speaker 03

  And that kind of protection is really only growing in importance because climate change is making powerful storms more likely.

• 7:22Emily Kwong?

  These trees are climate superheroes. They store more carbon, they protect from erosion. What is their third and last superpower?

• 7:30Speaker 02

  They are amazing for fish.

• 7:32Emily Kwong?

  Ah.

• 7:32Speaker 02

  Yeah, fish love to lay their eggs around mangrove roots. So I called up a scientist to talk about this one. Her name is Radhika Bhargava 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 roots.

• 8:08Emily Kwong?

  In the world?

• 8:09Speaker 02

  In the world.

• 8:10Emily Kwong?

  These trees are clearly exceptional. So, I mean, thinking about the history you were 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?

• 8:25Speaker 03

  Without the trees to do all that they do and, you know, provide that nursery for the fish, the ecosystem essentially collapsed. The shrimp, sardines, bream, crabs, the whole fish population, the

• 8:39Speaker 03

  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 stayed just had to struggle through these really difficult times.

• 8:57Emily Kwong?

  Yeah, okay.

• 8:58Speaker 02

  Yeah, and it's not just Koh 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.

• 9:15Speaker 03

  But Emily, this is the part where this turns into a good news story.

• 9:21Emily Kwong?

  It better, because that's what you've been promising.

• 9:23Speaker 03

  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 Kyosat 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.

• 9:50Speaker 02

  Yeah, and since 2003, Kyos village and a neighboring village, they've worked together to protect more than 145 acres of mangrove forests 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 and 2020, relative to the previous decade, according to a 2023 UN analysis.

• 10:25Emily Kwong?

  Oh, so you're saying that the loss of mangrove trees has slowed down considerably?

• 10:29Speaker 02

  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.

• 10:43Emily Kwong?

  Yeah.

• 10:44Speaker 03

  Rebecca and I got to see this restored and protected mangrove forest in Cambodia near Koh Kresna.

• 10:49Emily Kwong?

  Oh, amazing.

• 10:53Speaker 03

  So Mr. Sot 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. Egrets 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 nets full of fish. Others were motoring out to find their catch farther offshore.

• 11:38Speaker 03

  The whole place just felt alive.

• 11:39Emily Kwong?

  Wow. The ecosystems were bounding, 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.

• 11:57Speaker 02

  Yeah, totally. And we actually asked folks there about, you know, to what extent that larger impact is salient 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. Kyo Sot is now the chief of Koh Kresna and he's definitely aware of how his work connects to climate change. We also asked his son, Chien, what he thinks, and he was more forceful. He told us, "We are helping the whole world."

• 12:36Speaker 03

  And he's totally right.

• 12:39Emily Kwong?

  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.

• 12:46Speaker 03

  Thank you.

• 12:47Speaker 02

  Thanks so much.

• 12:50Emily Kwong?

  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 Neela Bannergy 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 Short Wave from NPR. See you next time.

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