The Current - How fungi could save the planet

Episode Date: February 3, 2026

“The future is fungal,” says Toby Kiers. She has won the "green Nobel" for her work studying mycorrhizal fungi — the vast underground network that acts as the soil's circulatory system. In fact, she may be the fungi's greatest champion. She explains why she loves these fungi — and why you should too.

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This is a CBC podcast. Hello, I'm Matt Galloway, and this is the current podcast. I'm officially going all in on team fungi after reading this study about how fungi helps sequester one-third of the carbon emitted by fossil fuels each year. My name is Simon Leonard. I'm a freshman forward, and outside of basketball, I like to look at mushrooms.

The coolest fact about a mushroom is that funguses interact with the roots of plants to form like a symbiotic relationship where they trade sugars from the tree in exchange for nutrients and water from the fungus. There are people out there who are crazy about mycelium, the underground parts of mushrooms. Even one of the stars of the hit TV show Hacks, Hannah Ionbinder, is a fan. Here is what she told Stephen Colbert. I am a total amateur mycologist.

Mycology is, for those who don't know, the study of mushrooms. I, like many Americans, see one documentary and become totally radicalized. did you get radicalized? What is it about fungus that you love? I guess the way that the mycelial network underground kind of holds the earth together and, you know, mushrooms, they do decompose and they do break down life, but they also make it possible for life to grow. And it's kind of this poetic, beautiful thing beneath our feet right now. Not the kind of thing you expect to hear on late night television, but these complex underground networks of fungi, perhaps of no bigger champion than Toby Kier's. Toby Kier's is an evolution.

biologist. She has dedicated her career to studying Michael Coraisal fungi, webs of filaments in the soil that make up a sort of circulatory system. This started when she was 19 years old. And three decades later, she is one of the world's leading experts. And now she has won the Tyler Prize for Environmental Achievement. It is sometimes called the Green Nobel Prize. Toby Kieres is also the co-founder of the Society for the Protection of Underground Networks. It's a group that's created a world atlas of fungi. She's in Amsterdam. Toby Kieres, hello. Hi, it's so wonderful to be here. This sounds like your people talking about, in poetic terms, about things living under the ground. Incredible to hear all of these voices championed for fungi around the world. Are we saying we should just be clear at the beginning. I, and I think in Canada, maybe we say fungi, you're saying fungi. Is there a correct way to say this?

That's the beautiful part about these organisms, is that there is no right way to say it. we can say it however we want. Excellent. Congratulations on this prize. As I said, this is like the green Nobel. This is a big deal. This is a big deal. This is the first time that Fungi have been recognized by this prize. And so I think we're all celebrating.

You said it felt like an award for the invisible. What did you mean by that? Well, I think a lot of what Fungi do is not recognized. I mean, they really lie at the base of life on Earth, but because we can't see them, they are vastly underappreciated. And they work as a decentralized organism. And they're in so many parts of our lives. They just, we just don't see it.

Why do you love them? Why do I love them? They're really like key engineers of our ecosystems. And I think one of the most important roles they play is to build soil. And as they're building soil, they are promoting biodiversity. I don't think many people know, but 59% of the Earth's biodiversity is unconstitutional. underground. And that's really because of a class of fungi called microizal fungi that form these beautiful networks with plants. And it's not just some plants. It's like 80 to 90 percent of all

plant species. And those networks really form an underground circulatory system. If you could kind of peel up, you know, the layer, the surface layer of forest floor, for example, and looking, what would you see when we talk about these underground networks? What would you actually see? It's so dense. They're so dense and so beautiful. So we've done a lot of imaging in the lab of a certain type of microizal fungi called arbuscular microisal fungi. And these are open tubes, literally beautiful, translucent open tubes. And if you could see into that tube, which we do with our high-resolution microscopy, it would almost look like a river, but a river moving in two directions at the same time, which when the biophysicists first saw this, they couldn't believe their eyes. But it makes sense because, because of course, the plant is providing carbon that needs to go, should be shuttled down to the tip of the fungi. And the fungi are collecting phosphorus and nitrogen and water. And they have to move that

up to the root system. So that's what you have coming out is a very dynamic flow of nutrients inside these networks. I remember speaking not so long ago with the Canadian scientist, Suzanne Samard. and she has studied this at length. And the phrase that was used to talk about her research was the wood wide web. What do you make of that? Well, what we try to say is that these organisms go beyond the forest.

So rather than saying the wood wide web, we really want to talk about the Earth's circulatory system because these networks, they're not just under forests, they're under grasslands, they're in deserts. I mean, these networks are incredibly important for desert plants to be able to get access to water. So a lot of our work, we're actually going and collecting in desert ecosystems. For example, the gobi desert, right? You don't even think of the gobi desert as being a place to

study these fungal networks, but they're very endemic networks, very specialized networks all over the world, but in the gobi that are really good at getting water. When you call it the circulatory system, I mean, I think people often will automatically think of their own, the human body and how important the circulatory system. is for us being alive. The comparison is intentional. Yeah, I don't think it's that far off. I mean, these networks, they're moving massive amounts of nutrient and carbon. So they're responsible for drawing down about 13 billion tons of CO2 into soil systems every year. So they give you a sense that's about a third of emissions from fossil fuels. And so you can actually imagine that this is

this underground circulatory system moving so much nutrients and water. And we're What makes me nervous is that we've really neglected to map and monitor and protect these fungal systems. What happened to you when you were 19 that you fell in love with the circulatory system under the ground? Well, I actually, when I was 19, I quit my undergraduate school and I moved to Panama to Barrow, Colorado Island, which is a small island in the middle of the Panama Canal. And I wanted to be a field biologist. And so I was so eager that I went out with so many of these scientists, this very small island. So you can't help but being brought along on these trips to study everything that's above ground. But that's what I realized.

All of these older scientists were studying everything above ground that they could see. And I became interested in what generated all of that diversity. Like where was that pulse of life that led to this crazy chaos of jungle above? So that's when I started my first experiment, was just digging up soil underneath these massive trees and using it as a source of fungi for seedlings of different types of plant species. Tell me about the experiments that you did to kind of set that light bulb off for you. Well, when we were moving the soil, you were taking soil from under one tree and growing and using it as an inoculum is what we say for other types of seedlings. And I remember the first time clearing out the root system of one of these tropical seedlings and actually seeing the fungi that were penetrating into the root. And it was so beautiful.

Like what you have to imagine is this beautiful tube that actually penetrates into a cell and makes a structure that looks like a mini tree inside a plant cell. It was such an intimate symbiosis that I started becoming interested in that tension, between what is parasitism and what is cooperation? Because it almost looked like a parasite. I mean, the fungus is penetrating into the plant cell. And that's what I studied for my PhD was this idea of looking at the evolution of cooperation and where partnerships form and what causes them to break down.

What were you doing? You were staining the roots of a tree with dye? Exactly. Tell me about that. What were you doing? We were taking a root system and then using a very heavy basic, like a chemical to clear out all the cellular content. So all that was left was just the structure and then dyeing it with a very intense blue color. And that made the fungus, which was invisible because its translucent sort of come into picture.

So it was almost like developing a photograph back in the olden days when we used to develop photographs. What was it like to see that? Well, I think it really catches your breath because you realize that there's an incredible underground world that has been invisible to us for so long. And when you think about a jungle, you know, these tropical ecosystems, there's so much life that you can see. But then it started, it really triggered me to start thinking, well, what led to that diversity? What generates all of that life? And that's where the fungus really comes in. As you said, the scientists that you were with when you were 19 there in the Panama Canal, they were paying attention to what was above the surface.

How did they react when you turn your attention to what is beneath the surface? Well, I think first they wanted to see the data. They wanted to see how important are these fungi really. And we had a very significant effect of using different soils. And once you could correlate that with how much fungi was in the root system, they started to be. convinced. I mean, you have to remember that at this time, it was just the start of molecular methods, so we didn't even know which fungi were there. But because these fungi that penetrate into the root, they make such a distinct feature that they knew that they were microizal fungi.

And it sort of started a whole line of research trying to understand, well, what is the effect of these fungi on the differential growth of tree seedlings? Because that really then could affect the way that forests generate. If all of these seedlings are growing at a different rate because of their fungal partners, that is what can help generate all this biodiversity above ground. Was there skepticism about what you were studying? I ask in part because it's out of sight, out of mind in some ways, right? Yeah, there was a lot of skepticism. I think because microasofungi, when they were first discovered, there was an overall sense that they were parasites because they were so intimately growing inside plant cells, which is exactly what a fungal parasite would look like.

And even in the start of my career, it wasn't clear. Scientists were not as convinced that these played an important role in the actual productivity or health of the plants themselves. So that came probably about a decade later. What convinced them? The data. Once you start seeing the data and you start realizing, you know, there were lots of experiments, Again, these are really old-fashioned experiments where fungicides were added to the soils

and the plants did poorly. And you could look into the root system and see that these structures weren't there. So that was pretty convincing. And now the data are really impressive in terms of even just trying to restore a degraded ecosystem. We had a paper out, I think it was in 2022, that found that using a healthy soil inoculum can lead to over 60% increase in biomass of plants. So these really help plants grow. And at the time, that just wasn't common knowledge.

This ascent isn't for everyone. You need grit to climb this high this often. You've got to be an underdog that always over delivers. You've got to be 6,500 hospital staff, 1,000 doctors, all doing so much with so little. You've got to be Scarborough. defined by our uphill battle and always striving towards new heights.

And you can help us keep climbing. Donate at lovescarborough.ca. Look, chances are your algorithm is still locked into everything that happened at this year's Grammy Awards, so let's talk about it. I'm Elamine, and this week on Commotion, I'm assembling the group chat to talk about the big winners and the surprises that no one saw coming

and the snubs that people are upset about from music's biggest night. Find and follow commotion with Alameen Abdul Mahmoud on YouTube, Spotify, or wherever you get your podcasts. You talked a little bit about trying to figure out the relationship between the fungi and the plants and the fact that you wondered whether they were parasites or not. You've talked about that relationship as a trading system. Exactly, exactly. So once I would say we started around 2010, we started being able to track the resources,

literally understand how much carbon being given by a plant was exchanged for how much phosphorus that the fungus itself would go out and gather. And so you can imagine that we set up these very, very precise experiments to test whether these systems, these plant fungal systems, followed similar economic principles to human systems. And with biophysics collaborators, we developed these imaging tools to really precisely track and quantify resource trade processes. And we started borrowing from economic theory to test these predictions. I think the most exciting thing that we've learned is that fungi, they're just not passive accessories, you know, but they're very dynamic and powerful actors in their own rights. And over some 450 million years, they've evolved very sophisticated trade.

strategies. I think it would stretch people's heads to hear them referred to as economic actors in some ways. Of course, because these are decentralized organisms that have no central nervous system. But for example, let me talk to you about some of these trade strategies. You know, the fungus will avoid sending phosphorus to plants that are growing in a shade environment. They consistently are sending them to plants growing in the sunshine. The fungi will trade differently depending how many fungal competitors are present. They'll hoard resources in their networks to artificially inflate the price and get more carbon because then the plants get so desperate. They'll invest differently in how much they put into their network depending on how

many other plants are connected. So we can start doing these very precise experiments. And again, this is laboratory work. And as soon as you move it out into nature, things get really, really complicated, but we've been able to study trade in these underground markets. What does that tell you? I mean, the danger in some ways is to anthropomorphize what's going on in nature, and I'm not saying that you're doing that, but it's almost that there is some element of intelligence that's going on there that is allowing the fungi to think in ways that are going to be advantageous, not just to themselves, but to the people that they want to work with. Well, exactly. I mean, fungi have no central nervous system.

no brain, but they do process information. And it's very important for them to get as much carbon as they can for how much phosphorus they're trading. And so through natural selection, they have really honed in on those trade strategies that allow them to get as much carbon. So it's not about anthropomorphizing, but it is about appreciating their ability to process information. I mean, I think in many ways, they're much better traders than humans. So I think we would have more to learn from them than they would have to learn from us. But because of the techniques that we've been developing in the lab, we can follow this much more closely.

We've started doing work with an imaging robot that actually allows us to track about 500, half a million fungal nodes at any given time, across the network. So you can think of each of those nodes as a decision made by the fungus to go left, to go right, to fuse, how to form this trade network. And then at every single one of those coordinates, we can zoom in and look at the movement of nutrients, which is like the traffic of carbon and phosphorus. It's a totally sci-fi world out there when you start working with these techniques, but it really allows us to understand not only how they trade, but how they build these supply chains to go out and actually collect the nutrients and use that to then build their bodies and move carbon.

It does sound like a sci-fi world, doesn't it? It does. It does. But there's a lot we can do now with really high-resolution imaging and trying to understand the inner lives of fungi. I mean, I think that's what's interesting and what's really hooked me is that they're divas in many ways. They're hard to study. They're slow-growing. You need an incredible amount of patience.

but they're also incredibly sensitive to their outside environment. So let me give you an example. If we are doing some imaging and watching the flows inside the network, if we lift the lid of the petri plate that we're working with and just breathe, just talk to the fungi, it changes the dynamics of flow inside the network. And you can watch it in real time on the screen. So you're interacting with it in quite an intimate way. You said something earlier, which is that you worry about the fact that we're neglecting this world.

I mean, that sounds obvious, again, out of sight, out of mind. But what are you most concerned about? Well, I'm concerned about the destruction of these underground fungal systems. So I'm talking about deforestation. I'm talking about high-intensity agriculture, land use change, urbanization, concrete. I mean, you can imagine how dangerous concrete is to pour. over these communities. And so what we're trying to do before it's too late is build these global maps of these micro-aiso communities to say who is where and really understand what they're

doing across some of the most remote ecosystems on Earth. How extensive are those maps? I talked earlier about it being kind of like an Atlas. What have you built? Yeah, exactly. So we call it the underground Atlas and it's an online tool so anybody can explore to look at these predicted biodiversity patterns across the earth, but it's based on 2.8 billion fungal sequences, and it's incredible. What it allows you to do is sort of get the first idea of where these microisal biodiversity hotspots are located. They show up as very bright colors on this underground atlas. And what's surprising is that if we then overlay the protected areas across the earth, 90% of these microizal biodiversity hotspots lay outside protected areas.

So that is what gets me worried is that there's these hotspots that are currently unprotected. And you can almost think of these as like a library of solutions to so many things facing the world today. Like what? Well, pollution, for example. These networks are incredibly good at taking up heavy metals and sequestering them in their networks and protecting plants from them. So they're very useful in remediation after mining, for example. Microplastics, there's an interesting work emerging about how they can protect above-ground portions of the plants from microplastics. They're incredibly important in terms of restoration, right?

We need to understand that when you restore an ecosystem, you can't just restore what's happening above ground. You need to use fungi to help restore what's happening below ground. If we lose some of these biodiversity hotspots, we won't be able to restore our global lands that are becoming more and more degraded. Those are just a few examples where we can talk about agriculture. And some of these networks are very good at surviving in highly saline soils. So we had an expedition in Tunisia in places where it's the saltiest, driest ecosystems. And because of these locally adapted fungal networks, crops can survive. But what happens if those hot spots disappear?

That's what I'm worried about. How do you convince people to pay attention to something that they can't see? That's been hard. I mean, that's really been hard because what you're trying to do is pioneer a new way of understanding life on Earth. And it's hard when this understanding is invisible. I think the biggest challenge has been for people to flip their perspectives and think about underground ecosystems as where life begins. And to do that, we have to make the invisible visible. And so that's why we live in this incredibly exciting time

with new techniques emerging that allow us to get at that invisible system. But what do you mean about the flipping the perspective? We've talked a lot about the degree to which we don't understand, for example, what's happening in our oceans. We spent a lot of time thinking about getting off the planet and going into outer space, but there's this huge body of knowledge that we simply don't have about oceans. and that's a way to flip our perspective. What are you talking about here when you say flip our perspective?

Is that we need to pay more attention to what is under our feet? Yeah, in many ways we can think about the fungi lying at the base of what generates the life of our ecosystems that we appreciate so much today. You have to go back in time a little bit. So 450 million years ago, that partnership with aquatic plants and the first microizal fungi, they allowed plants to colonize land. So it was that one evolutionary innovation between fungi and the first plants

that allowed these ecosystems to generate. And through that 450 million years, these underground ecosystems have been generating incredible biodiversity that we have no idea how it works. What's going on? We think of dirt as dirt. But if you start thinking about it, an ocean ecosystem, there's so much to discover. So actually, we call ourselves underground astronauts

because there is a whole world under our feet that just hasn't been discovered. Let me ask you just a couple of things before I let you go. One is, when you think about the work that you still want to do, what is a question that you'd like to have answered about these fungi? I think it comes back to the information processing. This is really interesting, because Because we know that so much carbon is passing through these networks. But then when the fungi actually have control of that carbon, what causes it to go fast? What causes it to be made into these exudates that stay underground? These are key entry points to carbon into soil systems.

These networks are helping control our atmosphere, but we don't understand how they do it. And so by understanding how fungi process information across their network, what makes them move carbon in different ways, then I think we'll have a much better understanding of how fungi are connected to the atmosphere. And so finally, you win the Tyler Prize. You get a gold medallion, but you also get a big check for, what, $250,000, US. And you've said that you want to use the money to take a deep breath and actually dream. What are you dreaming about using that money for? I'm dreaming about people caring about fungi. I mean, it was so inspiring to hear the opening to this segment because I feel like that is where the future is.

I mean, the future is fungal. And people are going to start waking up and realizing that they play a really important part of their lives. And I just want to be part of that. The future is fungal. I said it. You said it. Let's see what happened.

next. It should be on a t-shirt. That's a great, that's a great slogan. I mean, you have TV stars that are on Stephen Colbert waxing about what you're, which you're obsessed with. That's a sign that you're on the right path, I think. I think we are. No, that was really good to hear.

I mean, it is. And it's just changed so much over my career and having people embrace fungi. I mean, they really do allow us a new way to reimagine the world. They offer new ways of tackling biodiversity and the climate crises. But we'd have to move fast to protect them. This is fascinating to hear about the work that you're doing. Congratulations on the recognition, but also thank you for explaining it in a way that I think many people who are listening will fall into the obsession that you have. Toby, thank you.

Thank you so much. Toby Kierz is a professor of evolutionary biology at Vry University in Amsterdam, co-founder of Spun and Society for the Protection of Underground Networks. Now you know more about fungi or fungi, depending on how you want to pronounce it. You've been listening to the current podcast. My name is Matt Galloway. Thanks for listening. I'll talk to you soon. For more CBC podcasts, go to CBC.ca slash podcasts.