Adding Subtraction to the Climate Toolkit: Discussing Carbon Dioxide Removal with Wil Burns

Notable Quotes

• Current decarbonization efforts are not yet doing enough: “If you look at the Paris Agreement, which calls for us to reduce temperatures well below 2° Celsius … there is a massive gap between [that] and what we're doing. And when I say massive, I mean somewhere between 15 to 20 billion tons of carbon dioxide between what we should be reducing emissions by and what we are reducing emissions by … At least at this point, we lack the political resolve to do what would be necessary to decarbonize the economy in a way that comports with what Paris is calling for.” (8:44)
• Corporate support can help make carbon storage viable, but is not forthcoming: “If corporate initiatives really start picking up steam, it may be that that provides a lot of the private sector funding that's critical to characterize these and determine which ones might be most viable. But it's a major challenge. These things aren't likely to be adopted by corporations with the price of carbon that we have right now, and the fact that they have to compete with fossil fuels that are still massively subsidized.” (17:19)
• Expanding carbon storage discussions: “Countries are only starting to discuss [carbon storage], and they're doing it with great hesitation. Going back to one of the things you said at the beginning: Why aren't we just decarbonizing our economy? A lot of these countries make that argument, though of course simultaneously while not decarbonizing their economies. So I think in the next couple of years, you will start to hear more discussion of governance than you have, but at this point it's largely academics that are making those arguments.” (26:39)

Top of the Stack

• "Dam Breaches in Michigan Raise Questions for Dam Maintenance Across the Nation," a Q&A with RFF's Margaret Walls

The Full Transcript

Daniel Raimi: Hello, and welcome to Resources Radio, a weekly podcast from Resources for the Future. I'm your host, Daniel Raimi. This week, we talk with Dr. Wil Burns, co-director of the Institute for Carbon Removal Law and Policy at American University. Wil and I will talk about the approaches and technologies that might be helpful in removing large amounts of carbon dioxide from the atmosphere. We'll talk about what governments and companies are doing to encourage the deployment of these options, and we'll discuss some of the risks and challenges that each approach brings. Stay with us.

Okay, Wil Burns from the Institute for Carbon Removal, thank you so much for joining us today on Resources Radio.

Wil Burns: It's great to be here.

Daniel Raimi: So, Wil, we're going to talk today about carbon dioxide removal, sometimes referred to as CDR, but we're going to try to avoid the acronym if we can, although I'm sure I'll bark it out at some point. But before we get into the substance of our conversation, can you tell us a little bit about how you got interested and how you started working on environmental issues?

Wil Burns: Yeah, I was very interested in animals when I was young, despite the fact that I grew up in an urban environment. I became increasingly concerned about the threats to species and worked originally with a think tank that focused on wildlife issues, and increasingly one of the primary threats to wildlife became climate change. And so it became a natural migration to focusing on climate issues, ultimately toward the midpoint in my career.

Daniel Raimi: That's really interesting. Yeah, we've done some episodes on biodiversity and other wildlife issues, and the thing your comment makes me think of is my toddler who knows about 10 words and three of them are names of animals: dog, cat, and fox.

Wil Burns: Absolutely. We have a profound connection, though now we have to figure out a better way to be better stewards.

Daniel Raimi: Yeah. Well, let's get started in our conversation about carbon dioxide removal by just simply defining the term. So can you tell us what the term means, and then give us a brief introduction to some of the specific technologies that actually constitute carbon dioxide removal?

Wil Burns: Sure. Carbon dioxide removal refers to processes or technologies that can actually remove carbon dioxide from the atmosphere after it's emitted. So by contrast with efforts to decarbonize the economy, to reduce the greenhouse gas emissions that cause climate change, carbon dioxide removal efforts seek to actually remove some of the carbon dioxide that's already in the atmosphere. And by doing so, it reduces the trapping of outgoing radiation that causes the warming that's associated with climate change.

Daniel Raimi: Great. That's really helpful. Can you maybe just outline a couple of the relevant technologies, ways that one might actually be able to remove carbon dioxide from the atmosphere?

Wil Burns: Sure. I'll try to highlight about four or five of the main ones that are being discussed. So one of them is afforestation and reforestation. So there are proposals to try to substantially increase the planting of trees where they may have existed before and have been felled or harvested or lost in other ways, or to plant trees in areas where we haven't before. As you know, trees take up carbon dioxide for the photosynthetic process, and so they can remove carbon dioxide.

Another approach that's being discussed is something called bioenergy with carbon capture and storage. The idea here is to use bioenergy feedstocks to produce energy, things like trees or crops or crop residues. And then when we burn those feedstocks to produce heat or electricity, or we use them to produce biofuels, we then capture the carbon dioxide from the flue stack, and we can pressurize it into a liquid and then ship it for storage either in terrestrial areas such as saline aquifers or in the world's oceans. And the idea here is that it's a "negative emissions" technology because when you plant the biofuel feedstock, it stores carbon dioxide, and then you capture the output of carbon dioxide, and then you plant more of these bioenergy feedstocks to keep the loop moving.

Another approach we're talking about is direct air capture. This technology involves introducing ambient air across an absorbent system that's comprised of something such as calcium or potassium hydroxide solutions, or aiming solutions, which separates out the carbon dioxide from the other constituent elements of the air. Again, it can then be pressurized into a liquid form. It can be stored, or it can be utilized for things such as chemicals or high strength materials, or maybe even the future for synthetic fuels.

Another approach is called enhanced mineral weathering. Over thousands and millions of years, certain rocks as they weather, rocks that contain high amounts of silicates such as olivine, take up carbon dioxide, and ultimately convert that carbon dioxide into carbonates and bicarbonates. And those materials ultimately wash into the world's oceans and are stored sometimes for thousands of years. The idea behind enhanced mineral weathering is to try to massively accelerate that process by grinding up large amounts of rock, spreading it on areas such as crop lands, where it could have co-benefits of enhancing productivity, and then taking up carbon dioxide at a much faster rate, and then ultimately storing it.

And then the last suite of things that I'd emphasize would be ocean-based approaches. There's proposals to try to increase the amount of phytoplankton in the world's oceans. Phytoplankton take up carbon dioxide. They're responsible for about half of the photosynthesis on earth. Some scientists believe that there are areas where there's a critical shortage of a micronutrient, which is iron, for phytoplankton production. And so they propose spreading iron filings over areas such as the Southern Ocean to increase phytoplankton production, which in turn would take in carbon dioxide. And then when those phytoplankton die, it would take some of that carbon dioxide to the bottom of the ocean, where it would be stored in sediments for hundreds of years.

One of the other ideas in the ocean is called ocean alkalinity enhancement. And this is utilizing things such as olivine again, or limestone to increase alkalinity in the ocean. And by doing so again, it would ultimately convert carbon dioxide into bicarbonates and carbonates, and could store them in the oceans potentially for thousands of years.

Daniel Raimi: Great. That's really useful. Thank you for those descriptions. And I imagine our listeners are thinking as they hear the descriptions of these, of some of the potential benefits, co-benefits, and some of the risks of these technologies. And we will talk about that in a few minutes. But first, can you give us a little bit of an idea for why are we talking about carbon dioxide removal? Sometimes when I have conversations with people about this topic, the first thing they say is: "Well, why are we even thinking about carbon dioxide removal? Don't we just need to think about reducing emissions from our current sources? Why are we trying to go negative?"

Wil Burns: Right. Yeah, it's a very good question. Well, there's a couple of reasons. One is the fact that at least in theory, we should be getting our act together and aggressively decarbonizing, but we're not. If you look at the Paris Agreement, which calls for us to reduce temperatures to well below two degrees Celsius, and at least aspiring to 1.5 degrees Celsius, there is a massive gap between what would be necessary to effectuate that from year-to-year and what we're doing. And when I say massive, I mean, somewhere between 15 to 20 billion tons of carbon dioxide between what we should be reducing emissions by and what we are reducing emissions by. And the United Nations environment program just released a new report that indicated that even though the pledges that countries have made are inadequate on their face, only seven of 24 of the major emitters are even meeting those pledges. And so the fact is that at least at this point, we lack the political resolve to do what would be necessary to decarbonize the economy in a way that comports with what Paris is calling for.

The other issue is we have put so much of these greenhouse gases into the atmosphere, and they stay in the atmosphere for so long that we're already close to passing critical thresholds. And so even at this point, if we start massive aggressive decarbonizing, it's likely that we would pass these thresholds without substantial amounts of carbon dioxide removal. The Intergovernmental Panel on Climate Change, which is the leading international scientific body on climate issues, ran all of these scenarios to hold temperatures to below two degrees Celsius, and 87 percent of those contemplated large-scale use of carbon dioxide removal technologies—meaning that ultimately by the middle of the century, we probably have to be removing somewhere between 15 to 20 billion tons from the atmosphere, along with aggressive decarbonization to be able to achieve these goals.

And so it's not an either-or. If we don't aggressively decarbonize, carbon dioxide removal technologies cannot be a silver bullet that saves our bacon. But at the same time, even if we do aggressively decarbonize at this point, we're going to need substantial commitments to carbon dioxide removal simultaneously.

Daniel Raimi: Right. So, you talked us through some of the major technologies a few minutes ago. Can you talk now about which specific technologies you think might be most likely to be deployed at large scale? Which of the technologies might be at the head of the pack, if you will?

Wil Burns: I hate to hedge on this, but it's hard for us to know at this point because a lot of these technologies simply are at either a bench research scale or at small prototype scales at this point. For example, direct air capture, we only have a few pilot plants, and we're not sure if we're going to be able to scale them up substantially. Some of the others, there's real questions of sustainability. Bioenergy with carbon capture and storage might require huge amounts of diversion of agricultural lands, which could raise food prices. It could require huge amounts of water. So it's likely that we're not going to be able to scale that up to maybe more than like one or two gigatons of carbon dioxide removal annually. Which means that some of these others are going to have to really step up the game if we're going to get to where we need to be.

Direct air capture, if its cost can be brought down, if the energy requirements can be brought down, might have the greatest prospects. There's some estimates that we could sequester somewhere between seven to 22 billion tons of carbon dioxide annually with direct air capture. It has a lot fewer risks in terms of land use diversion and water, but cost still remains a question, and we won't really know that until we scale up. And unfortunately, that's a major challenge in terms of the incentive structures right now to do so. Enhanced mineral weathering has high energy requirements. It has some risks in terms of fine particulates. It requires large amounts of extraction of rocks. And so it's probably going to play a fairly small role.

The ocean approaches, especially the alkalinity approach has high potential, but it also may have some high risks in terms of effects on ecosystems, and we need a lot more characterization. So we're at early stages. The one we know the most about is planting trees, but that's not without risk either. If you plant huge amounts of trees, you may have to do a lot of it on areas that were grasslands, for example, and that could have some real biodiversity impacts, could require large amounts of fertilizer and water. We're afraid of land grabs from people that rely on these areas for their livelihoods. And so we need a lot more characterization in that context also. So we're at very early days in terms of determining what the optimal mix would be and how much we can scale these up and how quickly.

Daniel Raimi: Right. That's all really well said and so useful to keep in mind that there are a lot of questions we need answered before these things are scaled to the scale that would be necessary to sort of achieve the large emissions reductions that we're talking about here. Can you talk now a little bit about what are some of the big efforts that governments or private groups are currently undergoing or pursuing to push these technologies out into the world? To either do research on them so that we understand some of the potential tradeoffs, or maybe to actually start deploying them in the world and see what we learn from either pilot experiments or smaller-scale deployment of some of these technologies?

Wil Burns: Right. Well, we have some efforts on almost all of these technologies that we talked about. For example, when we look at bioenergy with carbon capture and storage, there are a few pilot plants in the world. I think there's approximately 15 of them at this point and all at relatively modest scale. So we're starting to learn what those capabilities are. Direct air capture, there are three companies at the top of the pack that are all developing pilot plants that they believe can bring the cost down, because cost is the biggest consideration when it, when it comes to direct air capture to perhaps $200, maybe $100 per ton of carbon that's captured, at which point in the future, it could be economically viable.

A lot of these others that we're talking about, things like enhanced mineral weathering and the ocean-based approaches, there's been some field experiments in terms of ocean iron fertilization. The other two primarily remain largely in the lab. That may change quickly. One of the interesting things that's happening in the last year is you have a number of corporations, including Microsoft, Stripe, Salesforce that have started pledging that they are going to move to either carbon neutrality, or net negative emissions over the course of the next couple of decades. And they are starting to put funding into some of these things. For example, Stripe this week announced that it is going to fund four of these different approaches, including some funding for enhanced mineral weathering, which really hasn't had much funding at all to this point.

So if corporate initiatives really start picking up steam, it may be that that provides a lot of the private sector funding that's critical to characterize these and determine which ones might be most viable. But it's a major challenge. These things aren't likely to be adopted by corporations with the price of carbon that we have right now, and the fact that they have to compete with fossil fuels that are still massively subsidized and the research programs of governments remain pretty modest in most of these contexts.

Daniel Raimi: Right. Yeah, and the price of carbon that you mentioned in most places in the world being zero.

Wil Burns: Yes. Exactly.

Daniel Raimi: Which is an important number.

Wil Burns: Yeah.

Daniel Raimi: That's really useful. One topic that I hear about in the news and I haven't read up on very much, we have some colleagues at RFF who think hard about reforestation and afforestation. There have been some announcements from governments about pledges to do large-scale tree planting. Can you talk a little bit about where those efforts stand, or at least where those commitments stand?

Wil Burns: Right. One of the things that's been developed in the last couple of years is something called the Trillion Trees Initiative. And even President Trump, who is normally pretty hostile to climate initiatives endorsed this Trillion Trees Initiative at the latest Davos summit. So the idea would be exactly that, planting a trillion trees. There was a study a year ago that said that if you planted trees on about 900 million hectares of land, which is about 2.2 billion acres, you could store around 200 billion tons of carbon dioxide. And that would be a substantial part of this portfolio that we're talking about because ultimately a lot of people think that by the end of the century, we need to store about a thousand gigatons or a thousand billion tons of carbon dioxide through carbon dioxide removal. So that would be about a fifth of the way.

There's a lot of problems with talking about tree planning at that kind of scale. One is that these studies don't often account for the fact that the current ecosystems in which you would plant these trees are already storing a lot of carbon. And that might be as much as 85 percent of all the carbon that you're talking about through planting trees. Another thing is that if you're going to plant that many trees, and you're going to encompass 2.2 billion acres of land, which is about, I believe a third of the size of Africa, you're likely ... Yeah, it's a large amount of land. You're going to have to try to avoid land conflicts. And one of the areas that we're talking about planting a lot of trees would be in snow covered regions.

Well, in snow-covered regions, a lot of the incoming solar radiation is reflected away because these are highly reflective surfaces, ice surfaces. If you start to plant trees, it starts to absorb more of the incoming radiation, which means that it exerts a warming impact that might offset the benefits of sucking up more carbon dioxide. So the science is very complicated, and some of these researchers don't acknowledge really what that might mean. The other problem with this, well, two problems. One that I've heard before is we're talking about probably planting a lot of these trees in areas like savannas and grasslands, where there's high biodiversity that could potentially be lost by planting massive amounts of trees.

And then the last thing is: It's unclear with tree planning, if we're going to get long-term storage because of climate change itself. If you've looked at the massive forest fires in California, in Australia in the last couple of years associated with steadily increasing warming, we've lost massive amounts of carbon. In Australia for example, the forest fires in Australia produced as much carbon dioxide release as all of the emissions from Australia for the year. And so as temperatures increase, it's likely that a lot of the trees that we would plant would be lost. And there's lots of problems with monitoring too. A lot of times trees are planted, it's not done carefully. They're not monitored. They're lost very quickly. It's not necessarily an approach in which you can be confident that you're going to get long-term, large-scale sequestration. It doesn't mean we shouldn't do it, because if you're planting trees in certain areas, you do get ecosystem benefits and other benefits in terms of hydrology and so forth. But it is not by any means, in my opinion, a silver bullet.

Daniel Raimi: Right. Okay. So we've talked about the technologies, we've talked about some of their potential, we've talked about some of their risks. We've talked about how they're being deployed in the real world, particularly with private sector companies. That actually reminds me Wil, you mentioned a company called Stripe and their efforts. I've actually never heard of Stripe. What does that company do?

Wil Burns: Yeah, Stripe is a technology company. I think it's in the Silicon Valley, and it provides software so that companies can accept payments and manage their businesses online and in other ways.

Daniel Raimi: Okay, interesting. Yeah Microsoft, of course I had heard of, but not Stripe. Let's move on to the last substantive question I want to ask you about carbon dioxide removal, which is about governance. We had an episode a few weeks ago where we talked about solar geoengineering with David Keith. There's some overlap between this topic and that one, they're very different of course, but I think there's some overlap. And one of the most interesting areas that came up around solar geoengineering is concepts and challenges around governance and international cooperation. You know, this is a very broad question, so please feel free to answer it however you think appropriate. But what are some of the major governance issues that come to your mind when we think about the large-scale deployment of carbon dioxide removal regardless? And I know this will vary from technology to technology as well. So however you want to answer that. I'll leave it in your hands.

Wil Burns: Yeah. Governance of these technologies would probably have to happen at both the national level and the international level, depending on the technology. In some of these cases, you have technologies that could affect the global commons or could affect other countries. And you're probably going to need some kind of international treaty regime to be involved. For example, if you're going to put alkalinity into the oceans or fertilize the oceans with iron, it's going to have impacts in the global commons. And so probably the Law of the Sea Convention or the London Dumping Convention, or the Convention of Biological Diversity are going to be involved in those cases. In some cases, such as enhanced mineral weathering and direct air capture, for example, most of the impacts are likely to be at the national level.

And so you may be looking at things like in the United States, if you were to deploy this, the National Environmental Policy Act, which requires environmental impact statements for large-scale projects, or in cases where you might have fine particulates as I indicated from grinding up things. You might have regulations on the Clean Air Act or mining regulations. Some of these, it's going to be a question of how much we want to extend governance at the international level. For example, with bioenergy and carbon capture, most of that would probably be regulated at the national level. It's going to be land use questions, areas we're going to carve out for planning bio feedstocks. But if you're going to massively raise food prices in other parts of the world, because you're diverting agricultural lands now to develop these dedicated biofuel stocks, will the rest of the world have a right to demand that you look at what those impacts are? Especially since raising these food prices could affect some of the world's most vulnerable peoples in areas such as sub-Saharan Africa.

And so maybe the Paris Agreement might decide that countries that want to make pledges in this context have to take into account those potential adverse impacts. But this is again in very early stages, as is true with the technologies in parallel, countries really only are starting to discuss this, and they're doing it with great hesitation. Going back to one of the things you said at the beginning: Why aren't we just decarbonizing our economy? A lot of these countries make that argument, though of course simultaneously while not decarbonizing their economies. So I think in the next couple of years, you will start to hear more discussion of governance than you have, but at this point it's largely academics that are making those arguments.

Daniel Raimi: Right. Very interesting. And similar to the solar geoengineering discussion, I would expect that we're going to watch this play out in policy circles in the years to come and it's going to be very fascinating.

Wil Burns: Yep. I think we are, largely out of despair in some ways. As you know with the solar radiation discussion, there are some profound risks in that context, but we may have no choice given what the impacts of unchecked climate change would be in the world.

Daniel Raimi: Right. Well, on that somewhat downbeat note, I'm going to turn it upwards for the end of our conversation and ask you the same question that we ask all of our guests, which is what's at the top of your literal or metaphorical reading stack? So something you've watched or heard or listened to related to the environment, or maybe related to something else that you would enjoy, or that you have enjoyed and would recommend to our listeners. And I'll just start us off very briefly. I live in Michigan, and as some of our listeners may know, there were two dam breaches that happened in Michigan a couple of weeks ago because we had heavy rains. My basement flooded, so that was fun.

There's a really, really interesting question and answer article that just went up on the RFF website by Margaret Walls and Elizabeth Wason, who is our producer for the podcast. And it's a really, really informative piece. It's called “Dam Breaches in Michigan Raise Questions for Dam Maintenance Across the Nation.” So if you're interested in what some of the issues around the dams in Michigan and what it might tell us about the national context and the condition of dam infrastructure around the US I would highly recommend this piece. It's really fascinating. But how about you Wil, what's on the top of your stack?

Wil Burns: Yeah. Well, it's more of an image. One of the things that has been interesting during the worldwide lockdown related to COVID-19 is the reemergence of wildlife many times in urban areas. And so we've seen huge amounts of elephants, caribou, porcupines, you name it. And one of the things I think it reminds us, going back to what we talked about at the beginning, is that we share the earth with these species, and we have to find a way to coexist. And these species reemerging at a time when we're in lockdown emphasizes the fact that in many cases, we haven't found a way to effectively coexist and protect their interests. And so it's an opportunity to remind people of kind of the beauty and the grandeur of nature and the fact that we have to find a way to minimize our footprint on earth in a way that we can coexist with species that provide us a lot of direct benefits, and also provide us with a lot of joy.

Daniel Raimi: Cheers, very nicely said. Well, we'll end it there, and thank you again, Wil Burns for joining us on Resources Radio to talk about carbon dioxide removal. It's been a really fascinating discussion. Thank you so much.

Wil Burns: Thank you.

Daniel Raimi: You've been listening to Resources Radio. If you have a minute, we'd really appreciate you leaving us a rating or a comment on your podcast platform of choice. Also, feel free to send us your suggestions for future episodes. Resources Radio is a podcast from resources for the future. RFF is an independent nonprofit research institution in Washington, DC. Our mission is to improve environmental energy and natural resource decisions through impartial economic research and policy engagement. Learn more about us at rff.org.

The views expressed on this podcast are solely those of the participants. They do not necessarily represent the views of Resources for the Future, which does not take institutional positions on public policies. Resources Radio is produced by Elizabeth Wason with music by me, Daniel Raimi. Join us next week for another episode.