The increased concentration of CO2 in the atmosphere since pre-industrial times isn’t just driving climate change — it’s also making much of the world’s drylands greener with increased plant growth. This is known as the CO2 fertilization effect, and politicians sometimes cite it to rhetorically downplay the negative global impacts of climate change, saying it’s proof that more CO2 in the atmosphere is a good thing.
Our guest on this episode of the Mongabay Newscast says it’s not, and issues a warning against this misleading interpretation. Arden Burrell is a remote-sensing scientist who co-authored the first observation-based study of the desertification of drylands that considers the CO2 fertilization effect, climate change, and climate variability. His new research indicates that while 5 million hectares (12 million acres) of drylands — an area half the size of South Korea — have become desertified, the future of vegetation productivity is an open and debated question. In this conversation with co-host Rachel Donald, he unpacks what the data tell us about the status of the world’s drylands.
Drylands are “the world’s breadbasket,” Burrell says, making up 45% of the world’s agricultural land. Crops grown via these highly complex food systems are already experiencing reduced nutritional value due to rising CO2 levels. Drylands’ climate change-driven degradation has already impacted an estimated 213 million people.
Burrell says this “global greening” can be a net good, but the increase in vegetation could mask other problems. While the CO2 fertilization effect allows plants to use water more efficiently, this also leads to greater amounts of vegetation, and ecologists worry that with more plants in drylands, they may actually take up more water.
“With sustainable agriculture, CO2 fertilization is kind of a net good, but in some parts of the world it has been masking continued overuse, and it is an open question how long that can continue before the degradation gets severe enough,” Burrell says.
Global greening or not, Burrell stresses that his models are only a snapshot of climate impacts on drylands, which require further study. “The fact that plants can slightly grow better in a hotter climate is by no means a justification to run a global climate experiment, which we are currently running … without actually understanding what it’s going to do.”
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Banner image: The spiny forest is a dryland forest at the southern tip of Madagascar, and is considered one of the most ecologically important regions in the world. Many plants here are endemic and possess deep root systems to survive drought. Image by Rod Waddington via Wikimedia Commons (CC BY-SA 2.0).
Rachel Donald is a climate corruption reporter and the creator of Planet: Critical, the podcast and newsletter for a world in crisis. Her latest thoughts can be found at 𝕏 via @CrisisReports and at Bluesky via @racheldonald.bsky.social.
Mike DiGirolamo is a host & associate producer for Mongabay based in Sydney. He co-hosts and edits the Mongabay Newscast. Find him on LinkedIn, Bluesky and Instagram.
TranscriptNotice: Transcripts are machine and human generated and lightly edited for accuracy. They may contain errors.
Mike (narration): Welcome to the Mongabay Newscast. I’m your cohost Mike DiGirolamo. Bringing you weekly conversations with experts, authors, scientists, and activists, working on the front lines of conservation, shining a light on some of the most pressing issues facing our planets and holding people in power to account. This podcast is edited on Gadigal land. Today on the newscast, co-host Rachel Donald speaks with Arden Burrell, a remote sensing scientist at the Woods Hole Research Centre who has been studying the effects of CO2 on the world’s dry lands. Now recently in the news, you may have heard that with the vast increase of CO2 concentration in the atmosphere, since pre-industrial times, plants specifically in the drylands, are actually getting greener. It’s referred to as the CO2 fertilization effect. And while it may seem optimistic on the surface, Burrell explains that this global greening has negative implications for water usage, native flora, and the overall health of drylands. Despite the seemingly positive headline. Burrell and his colleagues demonstrate in their research that even considering global greening, climate change has degraded 12.6% of the world’s drylands, over 5 million hectares impacting 213 million people. The vast majority of which are in poor or developing economies. Drylands account for more than half of the world’s food production and support around 40% of the world’s population. Burrell explains why the complex issue of desertification remains a genuine threat to the world’s breadbasket. His research published in Nature Communications is the first observation-based study of desertification that includes climate change, the CO2 fertilization effect and climate variability. And he discusses all of it with Rachel. Coming up next.
Rachel: Arden, welcome to the show. It’s great to have you with us on the Mongabay’s podcast.
Arden: It’s nice to be here.
Rachel: So, you have been studying the desertification of dry lands for quite some time. But before we get into the nitty gritty, let’s start with the basic details. Could you begin by explaining first what a dry land is and what desertification is?
Arden: So, a dry land is any ecosystem in the world that is water limited. To explain water limited, water limited is any ecosystem where if you got more rainfall, you would get more plants. It includes things like deserts, savannas, dry subtropical forests. It accounts for about 40 percent of the world’s land surface, dry land ecosystems.
Rachel: That’s huge..
Arden: And desertification is the process of land degradation in these regions. The reason we really care about dry land ecosystems is because they’re the world’s breadbasket. They account for more than half of food production, approximately, depending how you work it out. And they have about 40 percent of the world’s population, but all of the classic bread baskets are dry land ecosystems.
Rachel: That’s interesting. I don’t think I would have assumed that. I’m not sure what I would have assumed they were. Does that mean that agricultural land tends to be on dry land?
Arden: A lot of it is not all of it, obviously, but a lot of like things like wheat and corn production predominantly occur in dry dry land ecosystems.
Rachel: And what’s been happening to dry land ecosystems over the past 40 years with regards to climate change?
Arden: That is a very big and very uh…uh, interesting and open question. Drylands are actually one of the most complicated ecosystems to understand the impacts of climate change on. Just stepping back a little bit. The reason drylands are really difficult to understand is that they have a really high degree of natural variability anyway. So, in most other parts of the world your climate year to year is fairly stable. You can have trends, but you know, in the Amazon every year you would expect certain temperatures and certain amount of rainfalls and it’s fairly predictable. The thing that makes drylands really difficult to understand is that they have huge degrees of inter annual variability. So, one year you might have a huge amount of rainfall, and then you might not get any rain for, or very little rain for ten years. Uh, you know. And that, that inter annual variability makes it very hard to study. Overall, like the rest of the world, drylands have been getting hotter. They’ve been experiencing more extreme weather, more droughts, more rainfall. Does that, does that answer your question?
Rachel: Yeah. So, our dry lands are vulnerable. I just, before we sort of keep going down that line of questioning, I just want to try and zoom out a little
Arden: Yeah, please do.
Rachel: So how would you study if this interannual variability is much bigger than in other parts of the world, how do you begin to study and model dry lands? Do you look over a 10-year period, 15, 20?
Arden: So… yes. You need to look over much larger periods of time. And particularly, you also need to understand what drives dryland variability. It depends, different dry lands have different drivers of variability, but one of the big things that affects it the large oceanic oscillation. So things like the El Nino Southern Oscillation…
Rachel: Right.
Arden: Sorry, El Nino and La Nina are the probably more famous things. So something that drives big changes in climate in these systems are these large ocean oscillations. They occur on decadal timescales like El Nino and La Nina seem to operate on a 15-year cycle approximately.
So that means that to study a dryland system, you need at least kind of 15 years as your absolute minimum length of time, and that’s only giving you one cycle. So ideally, you would want 30-year records. And the only place where we have that sort of record is satellite data.
Rachel: And why is that?
Arden: One, they’re… drylands are really large. Two, they’ve historically been understudied in terms of field data. Like there’s just far less field data available for dry land systems than other regions of the world. And even when field data exists, it’s often much shorter, like five to 10 years. The only kind of really long-term large-scale records that exist are satellite images.
Rachel: Right. Okay. Now, surely if you need such a huge timescale, this makes the kind of urgency with which we’re trying to understand the climate crisis impact on different ecosystem and different parts of the world particularly difficult to grasp because what’s changing in the past year or two years or four years, does that need to be taken into consideration within a 30-year time frame or can we see enough variations in kind of the extremes of what we’re seeing in more recent years to establish in particular how anthropogenic climate change is making these ecosystems more vulnerable to drought or to desertification.
Arden: So that’s a big question, and it’s a complicated answer. You need to do both. You need to look at the long-term trends, but also look at the extreme events, you know, extreme events like understanding extreme events very much requires you to have a history, like…the longer timescale you look back in time and you can compare it to the more you get a realistic understanding of extreme events. But without, so without long timescales, it’s really hard, like without, you know, 20, 30 years of records at least it’s hard to understand these events. But, when you start looking over those events, those timescales, you do start to see quite significant patterns, significant trends in temperature, large changes in rainfall…
Rachel: Could you go through some of the extremes that we are seeing?
Arden: So, I don’t have the numbers in front of me, but I believe that drylands are currently warming faster than the global average.
Rachel: Oh.
Arden: But not quite as extreme as the polar regions are like the Antarctic and Arctic are warming much faster, but dry lands are still warming significantly. But this is where it gets complicated because the effects of anthropogenic climate change in dry land ecosystems are also complicated by the increasing CO2 fertilization effect–
Rachel: –yes. I’m glad we’re getting onto that. Please explain it–
Arden: which actually kind of brings us to like the, the big point of not disagreement within the scientific field, but kind of divergence of results. If you just look at temperature and rainfall, it looks like dry lands are going to get much drier and much worse. If you just look at rainfall and temperature, it looks like desertification is going to increase substantially. The measure that has historically been used to do that is something called aridity index which is a measure of rainfall versus potential uh, evapotranspiration, which is how much water would evaporate if there was unlimited water. And if you look at that measure, it looks like there’ll be substantial expansion of dry lands and a substantial intensification of evaporation, which would, you know, more dry. The problem is that photosynthesis works by taking in CO2 and water, and that’s how plants grow. If there is more CO2 in the air, plants can grow more efficiently. And so, drylands have been experiencing this really kind of interesting phenomenon where over the last 30 years, they have been getting hotter, but they’ve also been getting greener.
Arden: There has been more plant growth in drylands over the last 30 years. In large parts of the Earth, and that is largely being driven by this CO2 fertilization effect.
Rachel: And that is this photosynthesis of plants drawing down carbon in order to generate themselves.
Arden: Yes, That’s it. And the reason it’s, I don’t know if I explained this particularly well the reason it’s uh, has a positive effect is if there’s more CO2 in the air, the plants can use less water for the same amount of growth. It’s easier for them to pull CO2 out of the atmosphere. Because as part of the photosynthesis process, they have to release a certain amount of water. They release water as part of the reaction. And so, you take in CO2 and you release water and oxygen and the plant keeps the carbon to grow. I’ve grossly oversimplified, but…
Rachel: That’s fine. That’s absolutely fine. Then that’s very interesting to me because I would have assumed that in addition to CO2, plants would also need water. The H2O and CO2 would be facilitating different parts of the, of the plant growth process, which I am now grossly oversimplifying, but–
Arden: It turns out. No. And the reason is, is kind of complicated. It’s to do with very, very complicated like maths about C and chemical formulas following different photosynthetic pathways. But , even if I tried to explain, I would do a terrible job of it. Uh, But particularly for plants of a certain type we call them C3 plants. More CO2 in the atmosphere makes them makes it easier for them to photosynthesize and therefore they use less water. Now there’s another type of plant called C4 plants where they have a different evolutionary history and therefore a different photosynthetic pathway. They are affected much less substantially than C3 plants. They’re the atmospheric constant. They’re already, it’s a more, more efficient mechanism, but all the plants using C3 (which is a large portion of the plants in dry land ecosystems) benefit from higher CO2 concentration. And so at least in the, over the last 30 years, in most regions, the increase in temperature has been offset by the increase in CO2.
Rachel: That’s fascinating, and if I may, one…something I particularly love and also am disgruntled by with regards to this fact is that it is a kind of a political spin sometimes from climate deniers. Which is–
Arden: that’s a big problem–
Rachel: yeah, don’t worry about the CO2 because we’ll have more plants.
Arden: Yeah…the All fact that plants can slightly grow better in a hotter climate is by no means a justification to run a global climate experiment, which we currently running without, without actually understanding what it’s going to do. It’s uh, yeah, definitely not a justification.
Rachel: Alright, so that slightly is important. So, when we think about the, the potential greening or the increase in vegetation productivity because of the CO2 fertilization effect, how green are we talking?
Arden: Ooh, that’s kind of hard to give you an exact number, but we’re probably talking in the order of, like 15 percent greener by sort of 2050, but, even maybe, maybe not, maybe it’s only like 10 percent greener but even just saying 10 percent greener is not the easiest thing to interpret because when you look at a satellite image, you’re looking at greenness as a proxy for total vegetation or the satellite image doesn’t tell you the exact amount of plants you have you have to interpret the information so an increasing greenness of, you know, 10 to 20 percent doesn’t necessarily translate to 10 to 20 percent growth in plants.
Rachel: Okay.
Arden: It could be more, it could be less depending where you are. It’s, complicated,
Rachel: And if these are C3 plants, which typically have evolved in dry lands as well, then it’s not as if we’re going to start seeing forests springing up
Arden: No
Rachel: in dry lands due greening effect. Right. Okay.
Arden: We’re just, what we’re really likely to see and what we’re likely to have been seeing is in some places the plants will just be a bit more productive, they’ll just grow a bit more. There’s also some evidence in some parts of the world that shrubs have started to encroach on grassland. So generally, there’s like a gradation of dry land ecosystems where you start off in dry forests. And as you keep getting drier, you go to scrub lands, like Savannah-style things. And then you eventually get all the way to deserts and then hyper arid deserts, which is the ones with no plants at all. So we have like a, a gradation and there is definitely some evidence in parts of the world that there has been a shift from grass to shrub along the boundaries between those ecosystem types. But also that’s a complicated and open question about, is this a change in the way we’re using the land? Is it changing grazing? Is it changing animals? There have been some studies that have linked it to CO2 fertilization, but it’s not definitive and it may depend regionally as well.
Rachel: So, regionally, is this what we are, generally the CO2 fertilization is what we’re seeing across the board, because I mean, I’m amazed by how many different things sort of can be dry lands, you know, deserts, savannahs, and it’s a huge, huge, I mean, 40 percent of our…so the planet’s land is huge, but this is an effect across the planet uh, which is what led you and your colleagues to conclude that only 4 percent of dry lands are now vulnerable to desertification because of the CO2 fertilization effect across the world.
Arden: Yeah, effectively the Co2 fertilization effect is offsetting us. They’re offsetting the damage of increasing the temperature at the moment.
Rachel: In those particular places.
Arden: Yeah, in the places that are not desertifying. In the places that are desertifying the temperature and rainfall trends are so severe that even the increased CO2 fertilization effect is not offsetting the decrease in rainfall.
Rachel: Mmm. All right, okay, then I suppose that leads me to a question. So with regards to the model that you used for this paper in 2024 about the fact that 4 percent of drylands are vulnerable to desertification because of the CO2 fertilization effect. What models are plugged in to arrive at that conclusion? I suppose what I’m trying to get at is, was there an increase in CO2 emissions between now and 2050?
Arden: Yes. So, the models that we used used to standard S. C. P. A point–so so stepping back the I. P. C. C. The International Panel on Climate Change as part of their development of models and the creation of standard reports creates these scenarios. And they’re the scenarios that different modeling groups all around the world plug into their models come up with different estimates of change. This particular study predominantly uses SAP it used to be called RCP 8.5, but they changed the name. Yeah. SSP five dash 8.5, which the short version is that’s assuming that humans do not substantially reverse CO2 emissions in the near future. But the thing about that particular pathway is at least out to 2050 the effect of different pathways is actually surprisingly small, like even even if humans stopped emitting like today, we just stopped putting any more CO2 into the atmosphere, we’ve still got kind of like a five or six year lag where the temperature would still go up year over year because there’s currently more CO2 in the, the, the atmosphere than the temperature of the planet should be given that equilibrium state. So, there’s already like a sort of five to 10 year lag in the system. So regardless of sort of your emission scenario, the paper that you’re referring to looks out to 2050 and it picked the kind of the higher estimate of emission scenarios, one of the worst cases. But out to 2050 the difference between different scenarios is surprisingly small. It’s just after 2050, where things start to diverge drastically, and you start to see the truly horrific differences of not managing CO2.
Rachel: And that’s because of accumulated emissions in the atmosphere. So, right. And this is the thing that’s quite difficult to kind of grasp when you’re looking at these models is that what we’re putting up to, there isn’t a one for one sort of relationship between what we emit today and then what happens today, because CO2 stays in the atmosphere for 80 years. So, all of the historical emissions from the past 80 years before we got a grip on climate change are also going to be impacting the world today.
Mike (narration): Not to step on Rachel’s toes. But CO2 actually stays in the atmosphere much longer than 80 years. it’s between 301,000 years, according to data from NASA. So, the scenario they’re describing here is actually even worse.
Arden: Absolutely. That’s why it’s so important to act now, to be, to be reducing emissions now, because we’ve already locked ourselves in for at least another decade of warming if we stop right now. So, every, you know, every year that we wait, it just gets harder and harder more of a problem.
Mike (narration): NASA backs up with Arden is explaining here, but it’s important to understand that if we stopped emitting greenhouse gases today, Temperatures would begin to plateau within several years and stay there basically for the rest of our lives and centuries to come. But if we don’t stop emitting. Temperatures will continue to rise.
Rachel: You might not be able to answer this question. This is one of those big step back questions as well. But if the, if the CO2 fertilization impact or effect on dry lands is that we might see less desertification than previously feared. What is the knock-on impact to surrounding ecosystems? Is that greening, global greening, a net benefit? Or would that then have sent oscillations down the Earth systems that could have negative second or third order effects?
Arden: That’s a kind of a complicated, very complicated question. The best example this is heaps of effects. The best one I could think of is that it buys us a little bit more time. The fact that the plants green a bit, and by greening, they’re growing. So effectively, they’re sequestering a little bit of carbon. It doesn’t offset the increased CO2 emissions, but it does slightly decrease them. It is a net benefit for the planet, but not enough to offset the actual damage we’re doing to the planet by increasing, by releasing large amounts of CO2 continuously.
Rachel: Yes, there’s no solution to that apart from stopping and trying to green more.
Arden: Yeah.
Mike (narration): Hey there. Thank you. As always for tuning in and listening to the Mongabay newscast. We really appreciate it. And all of your support, did you know, we recently launched a WhatsApp channel. If you like to stay connected with your friends and colleagues on WhatsApp, you can also connect with us there. I find a link to a QR code in the show notes of this episode. And of course you can always keep up on all things. Mongabay by subscribing to our newsletter, which is conveniently located in the upper right-hand corner of the landing page at mongabay.com. Now back to the conversation.
Rachel: Now, interestingly, I sort of went through and looked at some other papers around droughts and found that there was a 2023 paper, I will hyperlink the the name of it, but it showed that across biomes drought resistance is significantly declining and drought resilience is slightly decreasing. And there was another paper in 2024 that showed that the frequency and intensity of vegetation compound droughts, which is to do with soil moisture and other factors are projected to increase further irrespective of whether CO2 fertilization effect on vegetation growth is considered or not. So, it’s one of this, this CO2 fertilization in dry lands is one of those things where we might have, it would be a net benefit in those areas. But if you, again, zoom out and look at the entire Earth system, it’s only slightly offsetting a huge degradation across all ecosystems and all biomes, which to putting too much CO2 in the atmosphere.
Arden: Yeah. It’s also complicated. One thing, so taking a step back about climate models in general. Climate models are very good at testing the mean state. So, if you want to know the average temperature in 20 years, they are incredibly good at that and have been good at that for a long time. Where they struggle more and seem to be underestimating the extent of the problem is extreme events and compound events. So even if, you know, this paper that was written, uh, this 2024 paper was very much talking about the mean state, what it can’t account for and what we currently don’t really have a good way to account for is those really extreme drought events or temperature events, which might cause substantial dial back that might substantially offset the positive effects of the CO2 effect. And there currently isn’t like, this is a really big area of model development. Like trying to understand extremes is one of the main focuses of climate modeling at the moment.
Rachel: And I’m just thinking about the extreme events that we’ve seen even in this past week in Europe, where I am based, you know, huge flooding, which I think I read the news this morning, 16 people are dead from flash flooding in Europe. And so even though we have this kind of holistic understanding that we’ve already keep pushing past the 1.5 degree limit sort of-
Arden: -we’re well past it-
Rachel: -last year. Yeah. Yeah, yeah, yeah, yeah, even though we, and then, you know, oh, but “we’re back down again, so it’s okay!” No, we’re well past it, but there are these freak events that are happening, you know, parts of the Amazon that are on fire. And so, I don’t know if this is a relevant or a valid question because I’m not a scientist, but how helpful then is it actually to do these mean models that are looking at a global average rather than localized examples.
Arden: Well, the models are looking at global averages, but they’re also looking at regional averages. It’s just that they fail in the, they don’t fail. They just, it’s much harder from a… from like a statistical perspective, it’s much harder to predict accurately when you’re at the edge of a distribution. The more extreme an event is, the harder it is to make accurate predictions about it. So, models have a lot of use. They are very useful. They have and for a long time have been giving us substantial understanding of how our climate is changing. Where we’re still trying to improve is just those outlier events, those small extreme events. But the thing is that small, small extreme events can be very damaging and they’re often the ones that grab the headlines. But they aren’t necessarily the ones that do the most damage in a sense. Like a long decline in rainfall over many decades is probably going to do substantially more kind of damage to agriculture and damage to other things than a single heat wave or freak event. So there is definitely that you need to understand both and not being able to perfectly capture this in the extreme events yet does not discount the value of understanding the, the the long term trends.
Rachel: And I suppose as well, you can’t sort of validate what is or isn’t extreme without having an understanding of what the mean is.
Arden: Yes, exactly. The other thing I kind of didn’t mention before is that compared to other ecosystems dry land ecosystems, the native plants of dry land ecosystems are much more drought tolerant. These are regions where you have always had a history of droughts and then extreme rains and then droughts again. And so, the natural plants are much more drought tolerant. They can survive, they can rebound. It’s a little bit of a different thing if we’re talking about agriculture that’s occurring in dry lands. Because you know, a normal plant normal forest or grassland or something can handle dying back for a year or two. And then when it gets some more water growing back and recovering, that’s just part of its natural cycle. When we’re talking about food production, even, you know, a year or two without being able to grow substantial food crops, it has serious implications for food security. In, you know, parts of the world with more developed agriculture there are ways to offset this with, you know, complex irrigation systems, fertilizer, special variants of crops that are more drought hardened. But if we look at other parts of the world, poorer countries are substantially more vulnerable to those events.
Rachel: Yes, and 33 percent of the world’s population are supported by these dry lands. And thank you for raising that. It’s such a, an important point, understanding the difference between what is native and what might, you know, quite happily be fertilized by CO2 and grow back 10 to 20 percent stronger versus the crops that people depend on to survive that need their annual rainfall and need a more sort of stable climate in order to feed people. Hmm. And so, are there particular regions of the world where despite the CO2 fertilization effect we can model that growing or using this land for agriculture is going to become increasingly unstable?
Arden: That brings us to the other big driver. So so drylands you could crudely summarize the productivity and dry ecosystems as water, CO2, and then the other one is humans.
Rachel: Shocking.
Arden: So because we are kind of grazing and growing stuff on such a large portion of these ecosystems the different management practices have a substantial impact on the productivity of the ecosystems long term and the sustainability of ecosystems long term. And so, with sustainable agriculture CO2 fertilization is a kind of a net good, but in some parts of the world it has been masking continued overuse
Rachel: Hmm.
Arden: and it is an open question how long that can continue before the degradation gets severe enough to pose a major problem.
Rachel: That’s fascinating. Which parts of the world in particular are vulnerable to this potential masking effect?
Arden: So, there’s quite a few different regions. So, some of the areas that seem to be problematic in the most recent study that I did was the dry lands along the southern border of Russia and sort of, Kazakhstan area, some portions of Brazil, like the Catinga forest– I’m probably pronouncing that awfully– a few regions in the great plains of the U. S., some portions of Southern Africa. Again, they’re, they’re smaller regions, but–
Rachel: Correct me if I’m wrong, but those regions seem like they would be engaging in industrial agriculture.
Arden: Some of them are, some of them aren’t. And I should also mention that in some of those regions, there are like negative hotspots, but then also positive areas on either side. You wanna look at the map of it, it’s it’s a paper that I put out that was published in Nature Communications in think it was 2021, that it went up.
Rachel: We’ll hyperlink that in the show notes. And so do we have, you said you know, sustainable farming, are there particular land management systems that come out strong with regards to working with the variation of dry lands in order to perpetuate their fertile soils?
Arden: That exact question is outside of my personal expertise to give a definitive answer about a specific system. But, in general, ones that use water more efficiently are better. We have this problem in Australia. Substantial overuse of groundwater and river resources. So, ones that use more efficient the ones that aren’t trying to grow really water intensive crops. We had this problem a while back in Australia with cotton production being quite water intensive and then during drought events, the industry had some substantial issues growing variants of different crops that are more drought tolerant. That is an open area of research as well, and there’s been substantial improvements in that.
Rachel: But there are, we can say that there are certain agricultural systems that are better than others-
Arden: yes
Rachel: -with regards to sustaining drylands.
Arden: absolutely.
Rachel: Well, that’s a piece of good news. Haha. We have had different people on the show to discuss some of these systems, with really extraordinary results with regards to regreening and making ecosystems more resilient. Which is very good news and we will hyperlink those in the show notes as well for listeners that are interested in learning more about those. Arden, I think that we have covered absolutely everything that I wanted to discuss with you. If I may, I suppose my final cheeky question would be what are you studying next with regards to dry lands?
Arden: So, my recent stuff is actually about fires and understanding fire dynamics in these sort of regions. And that’s what I’m currently working on, because fire is a substantial driver of change in these regions, and fire seems to be increasing in frequency. As noted by some incredible fire, it’s sort of California in Australia in southern Siberia. So that’s what I’ve been researching recently.
Rachel: Could the fertilization effect that sees more vegetation productivity then contribute to increased fires in those areas?
Arden: Maybe. That’s really hard to disentangle with just, because also increased human activity is it leading to increased fires. The CO2 fertilization effect is probably increasing fuel loads, but-
Rachel: what’s that mean?
Arden: Fuel load is the amount of biomass, amount of burnable material. So, for something to be burnable, it needs to grow and then it ideally dies or dries out and so more growth does mean more fuel.
Rachel: Right.
Arden: But also, humans are one of the main causes of fire in a lot of different ecosystems, and so trying to disentangle increasing fuel loads versus just increased what’s known as anthropogenic ignitions is is definitely complicated and interesting.
Rachel: Well, listen, you let us know when that paper is out, and we’ll have you back on to discuss fires and drylands. Arden, thank you very much for your time today.
Arden: Absolutely. Pleasure.
Mike: Rachel, um, this was an incredibly fascinating conversation, and this topic is super important to discuss. It’s also kind of confusing in a lot of ways, and I really enjoyed the clarity that Arden brought to the conversation on this and, uh, yeah, your reflections and thoughts, what do you think?
Rachel: What do I think? Um, I think it’s just another really interesting example of how the minute details are critical with regards to local systems, and how you cannot extrapolate that out to make assumptions about bigger systems and yet you have to factor in those minute, uh, details in order to understand bigger systems. If that makes sense. It’s just kind of like in and zooming out at the same time constantly.
Mike: Yeah, totally. I mean, it was, um, the whole CO2 fertilization effect, has been getting a lot of press lately, right? And people are like, well, it’s causing global, you know, greening, but I appreciated how Arden, articulated that this is, you know, while it’s like, could be a positive thing in the short term in specific areas, really in the long term, the accumulation of CO2 in the atmosphere is still going to be a net negative for our global dry lands and the world. Like, I think that that fact is not getting communicated well enough along with that news and it’s kind of frustrating it, you know when it isn’t.
Rachel: Yeah, I was really glad we managed to have a little bit of a back and forth about, you know, the right-wing talking points with regards to CO2 and there being more plants. And I think it’s just emblematic of how difficult it must be to be a scientist at the moment to be, or even generally an academic, to be an expert, uh, to follow rigorous methodology, to be peer reviewed, to have to jump through so many intellectual hoops in order to arrive at hypotheses and then also conclusions or, you know, suggestions only for a tiny part of your argument to be picked up and deliberately misconstrued in order to play a wider political game, you know?
Mike: Yeah, and the other point he raised which you both talked about at length is this the fact that the global greening can actually mask water overuse. Because the other thing that was surprising to me, which you were like, wow, that’s quite surprising is that with the increased CO2 fertilization, the water efficiency increases, right? But he’s saying that that is masking water overuse, you know, and water scarcity and water availability, as we know, is an increasing problem. So that I thought was quite troubling. And the fact that that like that is not in from what I can see totally getting communicated in news about this. And so, him bringing that up was incredibly important. And I hope that people listening are taking note of that.
Rachel: Yeah, I think generally systems aren’t particularly being, communicated in news stories with regards to climate change. I mean, only barely have journalists begun to scratch the connection between, you know, economic forces and the climate crisis. Um, Mongabay is one of the only outlets to deliberately and consistently report on systems essentially. Which is wonderful and really, really necessary. Um, and to be honest, kind of, sorry, going off on a little other tangent here, but when he was talking about all of this and I asked him the question about, you know, how this would impact like neighboring ecosystems, we don’t really have, you know, we haven’t exactly looked at that. So, you know, I couldn’t say, I immediately thought of Anastasia Makarieva and the biotic pump theory. And I was like, Ooh, I wonder how an increase vegetation could potentially, um, impact the water flows in the area, what that would do then to the local ecosystem as a whole. You know, would it be then that a dry land would no longer be a dry land? What would increase water in that area? Then do with regards to knock on impacts to water availability for certain industries. Like it was, you know, it just it totally Yeah
Mike: Yeah. and the other thing that you and him discussed, which I’m I think is getting missed right now is the fact that the portion of dry lands that are being desertified are impacting hundreds of millions of people. And this is, that is a huge impact. And the, you know, the food scarcity and the availability of resources of all these, of all these people, mostly in countries that are developing their industrialization or their infrastructure, that is already a huge, huge problem. And it’s going to continue to be one. So, I hope that that is, that’s another point. I think that we should highlight here as well.
Rachel: Yeah, thank you very much for raising that I’ve actually got the figures here, and it’s desertification is affecting 213 million people 93 percent of who live in developing economies. So that is once again the world’s most vulnerable communities at the front line of climate change who have done almost nothing to contribute to climate change sort of being, you know, put deeply at risk because as, as you said, and as Arden also said, I mean, dry lands are predominantly used for agriculture, if they’re used for anything around the world and not just industrial agriculture, and so people depend on these lands in order to survive and they’re not going to be able to if they desertify.
Mike: Well, I think that that’s a pretty good summary. I think I think we can go ahead and, you know, close it down there.
Rachel: All right. Okay. Well, thank you so much, Mike. A pleasure as always.
Mike: An absolute pleasure, Rachel. Have a good one.
Rachel: You too.
Mike (narration): I encourage you to read Arden’s research published in Nature Communications. You can find a link to it here in the show notes. As always, if you’re enjoying the Mongabay Newscast or any of our podcast content, and you want to help us out, we encourage you to spread the word about the work we’re doing by telling a friend. Word of mouth is a great way to help expand our reach, but you can also support us by becoming a monthly sponsor via our Patreon page at patreon.com/Mongabay. Did you know that we’re a nonprofit news outlet? That’s right. And even just a dollar per month makes a big difference. And it helps us offset production costs and hosting fees. So, if you’re a fan of our audio reports from nature’s frontline, go to patreo.com/Mongabay to learn more and support the Mongabay Newscast, and all of our podcast content. You and your friends can join the listeners who have downloaded the Mongabay Newscast well over half a million times, by subscribing to this podcast, wherever you get your podcasts from, or you can download our app for Apple and Android devices. Just search either app store for the Mongabay Newscast app to gain fingertip access to new shows and all of our previous episodes. But you can also read our news and inspiration from nature’s frontline at mongabay.com or you can follow us on social media at find Mongabay via our accounts on LinkedIn at Mongabay News and on Instagram, Threads, Bluesky, Mastodon, Facebook and TikTok, where our handle is @Mongabay or on YouTube @Mongabay TV. Thank you as always for listening.