The supertree shielding coastlines and storing carbon

Summary

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Podcast Summary: "The Supertree Shielding Coastlines and Storing Carbon"

Podcast: Short Wave (NPR)
Episode Date: May 22, 2026
Hosts: Emily Kwong
Guests: Rebecca Hersher, Ryan Kelman

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Episode Overview

This episode, told as part of NPR's "Climate Solutions Week," explores the transformational role of mangrove trees in Cambodia—how they saved a community ravaged by war and economic collapse and how their unique ecological powers are helping buffer coastlines and slow climate change. Hosts Emily Kwong, with reporting colleagues Rebecca Hersher and Ryan Kelman, guide listeners through a tale of survival, scientific discovery, and hopeful environmental action.

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Key Discussion Points & Insights

1. Cambodia’s History and Aftermath (00:38 – 01:45)

• The narrative begins in post-Khmer Rouge Cambodia, after the collapse of a genocidal regime in 1979.
• The economy and infrastructure were devastated, and villagers struggled for basic necessities.

Quote:
"People had nothing, and so people in town cut down local mangrove trees to burn and make into charcoal, he says, to cook with."
– Rebecca Hersher (03:57)

2. What Makes Mangroves "Super" Trees (05:09 – 07:47)

The episode highlights three "superpowers" of mangrove trees:

A. Carbon Trapping (05:41 – 06:41)

• Mangroves store up to four times more carbon than other forests due to slow decomposition among their tangled, waterlogged roots.
• By locking away carbon, they reduce greenhouse gases in the atmosphere.

Quote:
"Mangrove forests trap way more carbon than other forests… because the stuff that falls into the water and gets trapped around mangrove roots decomposes really slowly."
– Rebecca Hersher (05:58)

B. Wave Attenuation (06:49 – 07:39)

• Their extensive root systems anchor soil and absorb storm surges, dramatically reducing coastal erosion and flooding.
• A mangrove forest a football field wide can cut wave height by two-thirds.

Quote:
"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."
– Ryan Kelman (07:13)

C. Marine Nursery (07:47 – 08:27)

• The roots serve as crucial nurseries for fish; the majority of fish humans eat start their lives in mangrove ecosystems.
• Dr. Radhika Bhargava Gajre confirms their essential role in global fisheries.

Quote:
"Majority of the fishes that we eat are supported by mangroves during their early childhood reproduction stages."
– Dr. Radhika Bhargava Gajre (08:03)

3. Collapse, Loss, and the Turning Point (08:42 – 09:38)

• Mangrove deforestation led to the collapse of local fisheries; economic and ecological disaster forced many to leave or pushed survivors to the brink.
• Globally, half of all mangroves are at risk of collapse by 2050 (according to the UN).

4. Restoration and Hope (09:38 – 11:10)

• Efforts since 2003, led by local leaders like Keo Sat in Koh Kresna village, have protected 145+ acres of mangroves and planted thousands of saplings.
• This mirrors global action: Net mangrove loss decreased by 44% (2010–2020 vs. prior decade, per 2023 UN report).
• If trends continue, the world may see a net increase in mangroves.

Quote:
"Since 2003, Keo’s village and a neighboring village, they've worked together to protect more than 145 acres of mangrove forest… Net loss of mangroves decreased by 44% ..."
– Rebecca Hersher (10:07)

5. On-the-Ground Impact (11:00 – 12:53)

• The restored mangroves teem with life: thriving fish, reptiles, birds, and renewed fishing income.
• Local leaders now see themselves as stewards for the planet in fighting climate change.

Quote:
"We are helping the whole world."
– Chien, son of village chief Keo Sat (12:53, paraphrased by hosts)

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Notable Quotes & Memorable Moments

• "Mangroves are basically punching way above their weight when it comes to trapping planet-warming gases before they can make it into the atmosphere."
  – Rebecca Hersher (06:33)

• "These trees are climate superheroes. They store more carbon, they protect from erosion…they are amazing for fish."
  – Emily Kwong (07:39)

• "Half of mangrove forests are at risk of collapse by 2050, according to the UN… But this is the part where this turns into a good news story."
  – Ryan Kelman (09:32)

• "Some magical trees being taken care of by some pretty cool people."
  – Emily Kwong (12:55)

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Important Timestamps for Key Segments

| Timestamp | Segment Description | |-----------|------------------------------------------| | 00:38 | Cambodia’s history and post-war poverty | | 03:57 | Survival and deforestation of mangroves | | 05:41 | Superpower #1: Carbon trapping | | 06:49 | Superpower #2: Wave attenuation | | 07:47 | Superpower #3: Marine nurseries | | 08:42 | Ecological collapse from mangrove loss | | 09:38 | Restoration efforts and global stats | | 11:00 | Vibrant restored mangrove ecosystem | | 12:53 | Local-global impact and hope |

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Episode Tone & Language

• Conversational, accessible, and infused with humor (e.g., "superpowers")
• Visually rich descriptions ("roots are aerial…floating above the water"), anchoring scientific facts in relatable imagery
• Hopeful and solutions-oriented, spotlighting community resilience and effective action

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Conclusion

The episode illuminates how the humble mangrove tree is a local lifeline and a global climate solution, providing vivid on-the-ground stories and clear science. Restoration is working, loss is slowing, and—if momentum continues—the impact could be profound far beyond Cambodia’s shores.

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Transcript

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[Emily Kwong]

You're listening to Short Wave 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.

[Rebecca Hersher]

Hi.

[Emily Kwong]

All right. Where are we going today?

[Ryan Kelman]

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.

[Emily Kwong]

Yeah, I'm familiar with this history. During the Cambodian genocide, It's estimated that 1.7 million people died. It was, it completely changed the course of history for that country.

[Ryan Kelman]

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.

[Rebecca Hersher]

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.

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Wow.

[Emily Kwong]

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

[Ryan Kelman]

Yeah. It's a wild tale and it all hinges on one type of tree today

[Emily Kwong]

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.

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[Emily 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?

[Rebecca Hersher]

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 Keo Sat. He was in his twenties when the Khmer Rouge fell. He was living in a small fishing village called Koh Kresna. It's right next to the O. 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.

[Ryan Kelman]

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.

[Emily 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.

[Ryan Kelman]

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

[Rebecca Hersher]

Yeah.

[Ryan Kelman]

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.

[Emily Kwong]

Super trees with three superpowers. Let's hear them. First up, super mangrove power.

[Rebecca Hersher]

Number one is it's trapping carbon. 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.

[Emily Kwong]

Grateful to them.

[Rebecca Hersher]

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.

[Emily 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.

[Rebecca Hersher]

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.

[Emily Kwong]

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

[Ryan Kelman]

Yeah.

[Emily Kwong]

Okay. What is mangrove superpower number two?

[Ryan Kelman]

Wave attenuation.

[Emily Kwong]

What is that?

[Rebecca Hersher]

What is that?

[Ryan Kelman]

Everyone's favorite. I don't know what that is.

[Emily Kwong]

It sounds really cool, though.

[Ryan Kelman]

It is very cool. The intricate root system we were talking about earlier holds tight to the mud in the soil around the trees. So they reduce erosion and absorb the power of storm surges.

[Emily Kwong]

Oh, yeah.

[Ryan Kelman]

So they end up protecting the inland areas from flooding.

[Emily Kwong]

That's amazing.

[Ryan Kelman]

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.

[Emily Kwong]

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

[Rebecca Hersher]

They are amazing for fish. Ah, 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.

[Emily Kwong]

Their roots are very good nurseries for baby fishes or even for mother fishes to go and lay their eg eggs. Majority of the fishes that we eat are supported by mangroves during their early childhood reproduction stages.

[Rebecca Hersher]

I just want to make sure you caught that. The majority of the fish we eat start in mangrove.

[Emily Kwong]

In the world.

[Rebecca Hersher]

In the world.

[Emily 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?

[Ryan Kelman]

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 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.

[Emily Kwong]

Yeah.

[Rebecca Hersher]

Okay. 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

[Ryan Kelman]

U.N. but, Emily, this is the part where this turns into a good news story.

[Emily Kwong]

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

[Ryan Kelman]

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.

[Rebecca Hersher]

Yeah. And since 2003, Keough's 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 between 2010 and 2020, relative to the previous decade, according to a 2023 UN analysis.

[Emily Kwong]

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

[Rebecca Hersher]

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 forest on Earth could actually have a net increase eventually.

[Emily Kwong]

Yeah.

[Ryan Kelman]

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

[Emily Kwong]

Amazing.

[Ryan Kelman]

So Mr. Stott 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. The whole place just felt alive.

[Emily 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.

[Rebecca Hersher]

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. Kiyosat 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.

[Ryan Kelman]

And he's totally right.

[Emily 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.

[Ryan Kelman]

Thank you.

[Rebecca Hersher]

Thanks so much.

[Emily 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 Banerjee and our showrunner, Rebecca Ramirez. Tyler Jones checked the facts. Jimmy Keeley 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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