Scientists have long known that trees are helpful in the fight against climate change, by taking carbon dioxide out of the air.
But new research finds trees are even more beneficial than we realized — microbes living in their bark can help remove methane from the atmosphere.
Alexander Shenkin is an assistant research professor at Northern Arizona University and director of the Ecosystem Science and Innovation Lab, where he does research on forests
Shenkin joined The Show to talk about what his research found.
Full conversation
MARK BRODIE: Were you surprised by what you found with this research?
ALEXANDER SHENKIN: Yeah, it was so my colleague, Vince Gauci from Birmingham discovered the process itself and when he told me about his discovery, it was quite surprising. Having said that, there are bacteria all over the place. And so, you know, they do all sorts of crazy things.
I guess the real surprise was when we scale this up across the forests around the world that it turns out to be a really important process of the global carbon cycle. That was the real kicker. I think when we all kind of said, oh wow, this is really something here.
BRODIE: So how exactly does this work? How does tree bark play a role here?
SHENKIN: Yeah, it's a good question. So it turns out that tree bark and what we call sap wood or the living wood underneath the bark plays host to bacteria of all types. And one of those types are called methanotrophs. They are bacteria that eat methane instead of oxygen for energy. And they exist there in very low amounts, especially because methane is really diffuse in our atmosphere. It's, it's very, there's just not much of it.
And so it doesn't support a large population, but it supports enough apparently to support the life of methanotrophs in tree bark and in the sapwood of these trees that yeah, so they consume methane to, to live.
BRODIE: How big of a dent do you think this could put into our efforts to, you know, reduce the amount of methane in the atmosphere?
SHENKIN: Right now, we figure that this is an additional 10% benefit say of trees to the cooling of our climate. Having said that it's something, it's it's nothing, it's not a new process, it's just a new process to humans, right? So we just discovered it.
I think the major impact that it could have, however, is by incentivizing catalyzing more reforestation of forest conservation if we are able to recognize this additional benefit, that forest and trees are providing in the carbon market.
So carbon market is not familiar to everyone. But the basic idea is that if you grow a forest, say in Brazil, that wouldn't have been there otherwise. And that is sucking up carbon, then you can trade those credits to Microsoft say who is looking to lower their overall emissions. So essentially Microsoft pays to reforest so that a force in Brazil sucks up the carbon that it's spitting out in its, you know, cloud computing factories.
BRODIE: Do you think that this knowledge will help move along some of those efforts? Because as you point out, you know, this has been going on for, you know, for as long as trees have been there, whether or not we as humans have known that it's going on.
So do you think that by saying, OK, this is even more beneficial, trees are even more beneficial to the environment than we thought that maybe help some of these projects get off the ground?
SHENKIN: I think so. So we actually launched a spin off company called SelvaFlux and we've done some initial models, economic models on it. And you know, if, if we integrate these carbon credits into tropical reforestation products, sorry, projects, the benefit to the carbon credit should be around 30% more than what they get with just considering the kind of CO2 that these seedlings are taking up. And if we are able to turn those into carbon credits. Then yes, it will incentivize these companies, these, these forest project developers to do on average around 50% more projects.
BRODIE: Does it seem to matter what type of tree you're looking at when, when you're talking about, you know, taking methane out of the atmosphere?
SHENKIN: That's such a great question. And, you know, this is one of the questions we get like one of the first questions that everyone asks us is what about different tree species? You know? And, and yeah, it's a fascinating question. What controls how much because they vary a lot, you know, by a factor of five or more.
One tree will be taken up a little bit and another tree will be taken up five times as much. We don't know. So this is an open research question. What is it that controls, you know, so number one, which species take more or less? And then number two, why?
BRODIE: Yeah. Well, it seems like it would really matter in terms of, as you say, where these projects might be more beneficial than others. For example, you know, trees that grow in the Amazon rainforest, I would imagine are very different than the trees that, you know, might grow in the forests of, you know, central or northern Arizona where, you know, you can have fires or other, you know, deforestation efforts in both. So it would really matter like where these projects might work, right.
SHENKIN: That's exactly right. It matters a lot. The species question is still up in the air. But the kind of spatial variation is one that we've gotten a little bit of clarity on. So it turns out that trees in the tropics do this a lot faster than they do say here in Arizona. The best correlation we get is with mean annual temperatures. So wherever it's kind of hotter throughout the year versus wherever it's, it's, you know, not so hot throughout the year.
Of course, Phoenix plenty hot throughout the year, but that's also dry. So it may have to do with not just mean annual temperature but also the humidity that kind of supports the growth of these bacteria in this bark. So think of an urban tree in Phoenix or you know, a creosote bush somewhere around there that they, you know, they are very conservative with water for, for obvious reasons. And you know, it's probably not a great environment for bacteria in the park there versus a tree in the Amazon.
BRODIE: Is it possible, do you think, to simulate the effect of the tree bark? And I ask because for example, you know, there are researchers at ASU who have put up these fake trees in different places to, you know, to take the carbon dioxide out of the air.
I wonder if it's possible to do that with a sort of fake tree bark, if you can't actually grow that kind of tree in a place where taking methane out of the atmosphere would be helpful.
SHENKIN: What a cool idea. We'll put that on our list. I think so one active area of research that my colleague is pursuing is looking at the micro biological communities that give rise to this process and if they can be amended, so, can we add, say nutrients to help these bacteria grow faster and you know, more numerous and therefore process the the methane faster in existing tree bar.
The question of, yeah, like fake bark or maybe like kind of hanging gardens or something like that. Something along those lines would be really neat. I think, you know, these little critters need nutrients, right? So it's not going to work like a piece of plastic. But if we can come up with that, that's a cool idea. I'm sure there will be all sorts of interesting developments that come out of this.
