Reversing Climate Change is many things: a repository of deep dives into carbon removal, a way to intimately understand the thought processes of the folks at Nori working to build a scalable carbon removal marketplace, and a massive catalogue of the infinite number of climate-adjacencies that tickle host Ross Kenyon's brain. And sometimes you've got to get back to basics and reintroduce a topic to catch new listeners up. To that effect, today's show is twenty minutes on the basics of carbon removal.
In this episode, Ross Kenon, Cofounder of and Director of Creative & Marketing at the Nori carbon removal marketplace, chats with Nori's Head of Supply and Methodology, Radhika Moolgavkar, about carbon removal—what it is and why it's necessary.
They discuss the differences between open and closed CDR systems, the need for a combination of all carbon removal technologies, and why carbon accounting is so complex. They also touch on the intersection of carbon removal technologies with the oil and gas industry and the geopolitical considerations involved in carbon removal strategies.
The episode serves as a resource for listeners who are new to the concept of carbon removal! If you are new to CDR, start here!
Timestamps:
00:00 Introduction
00:41 Understanding Carbon Removal
03:18 The Importance of Carbon Removal
05:40 Types of Carbon Removal
14:02 Challenges in Carbon Accounting
18:16 The Role of Oil and Gas in Carbon Removal
19:55 Conclusion
Resources
If you want to deep dive into carbon removal and are considering a career change, AirMiners Boot Up is a great place to start.
Also on this show
Mixing fast and slow carbon: the Nori blended tonne, with Radhika Moolgavkar, June 2023
How Nori created a direct air capture and storage methodology, with Radhika Moolgavkar and Rick Berg, February 2025
More from the show
Ad-free episodes and other benefits come with a paid subscription.
Carbon Removal Newsroom, the news show that ran alongside this one, is over. Its episodes are still up, on the feed Climate Workers Anonymous now uses.
Carbon Removal Memes is still going.
The books that come up on this show are collected on my Bookshop shelf.
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Full Transcript
Ross Kenyon: You’re listening to the Reversing Climate Change podcast by the team at Nori, the carbon removal marketplace. This is a show about the innovators and entrepreneurs developing solutions to climate change. You’ve got to keep this all in. You’ve got to keep it all. Yeah. Sorry. Yeah, this doesn’t happen when I have big fancy-pants guests here. Just when I have, you know, everyday rigmarole Radhika over here.
Radhika Moolgavkar: I get it. I get it.
Ross Kenyon: Radhika Moolgavkar, Head of Supply and Methodology here at Nori. Hi, Radhika.
Radhika Moolgavkar: Hi, Ross. How are you?
Ross Kenyon: Hi, I’m doing well. I’m introducing the show right now. I’m Ross Kenyon. I’m one of the cofounders of Nori. I’m also the Director of Creative and Marketing. Nori is a carbon removal marketplace based in Seattle, Washington. We get so esoteric sometimes. We’re always talking about strange ideas and connections and climate adjacencies, and we thought it was time to go back to basics here.
What is carbon removal? We haven’t done a show that reintroduces this, and I don’t even know how long. I can’t even remember. Probably been several years. We’re due. So if you’re looking for a place to join this show, you don’t know much about carbon removal, we’re hoping this will be a fine resource to start with. And Radhika, does that put the pressure too high, or do you think you can deliver on explaining what exactly carbon removal is?
Radhika Moolgavkar: Well, I can certainly do my best, but as you know, Ross, there’s lots of debates within the industry, so we’ll keep it pretty high level and I think I can hit the points. And I would also point out that if anyone wants to do a deeper dive into carbon removal, they should definitely check out our other podcast, Carbon Removal Newsroom, where we go deep into all the parts of carbon removal.
Ross Kenyon: Have you ever listened to the a16z podcast a long time ago? It’s been a long time for me too, because I find it quite alienating because you need to speak venture capitalist to make sense of it, all of the things that they throw around. We like Carbon Removal Newsroom is where we eventually want to steer people towards, where it’s just the deep insiders. This is where the hardcore news happens. And maybe you’re listening to this show and you’re not quite ready for that, but we’re trying to get you to the point where you can go listen to Radhika’s show and be there. So, Radhika, let’s start off: what is carbon removal?
Radhika Moolgavkar: Yeah, so carbon removal at its most basic is removing carbon from the atmosphere, as everybody knows. Or CO2, to be technical. And to be technical, maybe CO2 equivalents. But essentially it’s removing—
Ross Kenyon: [unclear] get through a single sentence without having to nuance it to death? Is that— is that going to be the—
Radhika Moolgavkar: No, no. I just felt like I needed to be clear because, you know, in my own world I try to make a distinction between emissions, which are the CO2, and carbon, which is what’s stored in the ground. So there you go, that’s what carbon removal is. You take CO2 from the air and you store it in various mechanisms in the Earth and remove it from the atmosphere, therefore carbon removal.
Ross Kenyon: It’s a good definition, and also maybe a good first lesson here that climate change, climate tech, carbon removal, these are industries or sectors where the details matter a lot, and you’ll see people engaged in highly technical debates because these things do matter. And being too hand-wavy has caused a number of problems with carbon markets in the past, I think it’s fair to say. Do you agree with that?
Radhika Moolgavkar: Yeah, I agree with that. And I think it’s a continued theme that we address every day at Nori.
Ross Kenyon: Is carbon removal necessary? Can we not electrify everything, right? Why suck it out of the air? People often complain that it’s a techno fix, that it doesn’t make sense. But alternatively, people will say that trees burn down, that we can’t plant enough trees, there’s not enough arable land. Do we even need to be bothered with this, or can we just decarbonize and stop emitting fossil fuel emissions?
Radhika Moolgavkar: Well, of course we need to do that, and we need to do that as quickly as possible. But I think most recently, maybe it was in 2021, the IPCC, which for those folks who are not familiar is part of the UN body and they’re a scientific advisory board, most definitely said carbon removal is necessary because we’ve gone way past the parts per million where just decarbonizing the entire grid and everything else will suffice. So I do think it’s necessary.
There are some arguments that groups make about the moral hazard of carbon removal, which is essentially that if you have a way to remove the carbon, that might give corporations license to continue to emit. I would argue that we’re past that point and that we have to throw every solution out there because it’s too late. We’re past the point where we can just wait for emission reduction to come into play fully.
Ross Kenyon: Was there ever a point where we could have stopped emitting and it would have been OK? I think I’ve heard maybe the ’80s was the last time.
Radhika Moolgavkar: Yeah, maybe the ’80s, the early ’90s. So it’s taken a long time probably for people to even come around to this vision, the scientists and things. But I do think what we’re seeing is many of the models and curves that people were predicting around the acceleration of climate change and temperature rise are starting to come true. This summer was a really good example of that. And so whatever should have happened in the ’80s or ’90s, we’re way past that. And now we just need to accept the place we’re in and work as fast as we can to scale emissions reductions, electrification, and carbon removal.
Ross Kenyon: I’ve named a few types of carbon removal and there are many more. I imagine people listening have at least a basic familiarity with some of them. Can you sketch out what are the families of methodologies, or means of removing carbon from the atmosphere?
Radhika Moolgavkar: Yeah, I would say at the most, you know, basic level, there are two ways of removing carbon from the air. One is through photosynthesis. I think probably most people on this call will be super familiar with that idea. Plants suck carbon dioxide from the air and they store it in the soil. So you can use forests, you can use regenerative agriculture, you can plant native grasslands, all of that ecosystem restoration around mangroves. All of that is great at sucking carbon out of the air, and it’s what’s been doing it since the Earth pretty much existed.
The other way of sucking carbon out of the air is much more engineered. It’s usually considered DAC, which is direct air capture, or other versions of that. And that is basically using machines and engineering and a lot of energy. So it can be, you know, complex to suck the carbon dioxide out of the air, separate it from the rest of the air, if you will, and then store it in the ground. And so those are the two broadest categories.
Then within that you have different types of carbon removal, and then you have oceans, which also do types of carbon removal, again sort of merging these two ideas together in ocean. Sometimes they take an engineered and a photosynthetic approach. So lots of areas, but I think about them at the most basic as those two types: photosynthesis and engineering.
Ross Kenyon: I know certain kinds of rocks can, if left out in ambient air or even in a concentrated environment, absorb carbon dioxide or other types of greenhouse gases. Is that engineered? Is that photosynthetic? But it’s photosynthetic.
Radhika Moolgavkar: Yeah, you’re making a good point, and this is where all these nuances come in. But yes, that’s called enhanced rock weathering. But in a way that’s a natural solution, right? That is something that has existed in the Earth in various mechanisms, probably again since the beginning of time. However, what we’re doing in carbon removal is we are enhancing it, either through the way we apply it or the size of the rock or whatever. So there are what I would call hybrid solutions, which, you know, involve some engineering in the sense that you’re not just letting a plant grow, but you have to do some application of human intervention that then transitions to a nature-based solution.
So another way to think about carbon removal is open systems and closed systems. So closed systems are things like DAC and some types of biological storage where you can literally track the molecule almost from when it was created in the air until it’s stored, and it’s very much, like I said, a closed system. Open systems are things like what you described, where there are other impacts from the environment that either accelerate or can sometimes prevent carbon removal. Things like enhanced rock weathering, forestry — because, you know, something grows but then can get cut down — regenerative agriculture. All of those are open systems, because their nature impacts the way you measure it and the way it happens.
Ross Kenyon: Is it easier to measure closed systems and harder to measure open systems?
Radhika Moolgavkar: Yep, yes it is. Categorically, yes. I mean, they’re not — then I want to be clear, that’s not to say that closed systems are better, because they have their own set of challenges. But from just a pure measurement perspective, yes, there are much fewer conflating factors in closed systems — by their nature they’re closed — than open systems, where you’re dealing with environmental factors that are much harder to quantify and measure.
Ross Kenyon: Is there any sense that you have of what are the families of techniques here that we should be focusing on as a society, or do you think we need to be doing all of them?
Radhika Moolgavkar: Yeah, I mean, my philosophy right now is you’ve got to do all of them because they’ve all got their strengths and weaknesses. We’ve talked about regenerative agriculture. There’s a compound called biochar, which is, you know, taking biomass and converting it basically into very stable carbon through heat and pressure. There’s also things like forestry, like we’ve talked about and I think a lot of people are probably familiar with. Those are all things that are, like we talked about, hard to measure, but they’re also generally very accessible. Today you can really do large-scale mitigation and large-scale carbon removal with the techniques known in those types of processes, if you will, or pathways, as we like to say in carbon removal.
On the other hand, they may not scale to the levels we need, because you have finite soils, you have, you know, finite places for regenerative agriculture, and they’re stored in a different way than the emissions that we released. Storage in soil, I think most people would, you know, inherently understand, is different than storage well under the ground in a rock formation. So then you have the other types of techniques that allow you to do geological storage, but they are much less efficient right now. They’re much harder to measure and verify in some cases. And so you need both, because we’re rapidly reaching tipping points, sort of temperatures where if we go past it, we don’t know what it means.
Carbon removal through these, you know, forestry, soil, biochar, etcetera, allows us to avoid those worst outcomes, sort of kick the can down the road, if you will, while these more maybe experimental techniques get further along in development and then can ramp up and really do massive scales of carbon removal. So I see this sort of as a wave, and we’re in the very early stages of the wave, and as it grows, more of these carbon removal strategies will come online. But for now, we’re in the early days. And so we really should not discount things like soil, forestry, etcetera.
Ross Kenyon: Your framing of this is that temporary carbon removal is good because while it might not permanently negate emissions, it is going to buy us time for more experimental technologies to come online.
Radhika Moolgavkar: That’s exactly what I was trying to say, much more specific.
Ross Kenyon: How should someone think about what to support right now?
Radhika Moolgavkar: I think there are a lot of ways to approach it. You know, I think for some group of people they’re very techno-forward and they’re very interested in engineered solutions, and maybe they should be looking at buying carbon removal through things like DAC or even maybe enhanced rock weathering, where there’s a huge scientific component. It’s sort of experimental and people are learning a lot, and that might appeal to a certain segment of the population. However, that is a delayed gratification, because you’re not going to get credits for a while and you certainly cannot use it in the traditional carbon accounting way today.
And then, you know, there are other people who might be drawn to things like regenerative farming and reforestation and ecosystem restoration, because, one, it is carbon removal today. But it also is doing so — there’s so many ecosystem benefits that go along with these different technologies, right? You’re rehabilitating the soil, which does things like increased water retention. You’re bringing in biodiversity. All these things, while maybe not directly tied to carbon removal, are very important for keeping the Earth healthy.
And so some people might, you know, value the carbon accounting aspect less, which we can get into in a second, and be more interested in all the amazing benefits that these techniques support. And then there are people who might want to do a mix, right, because they’re interested in both things. So I think there’s so many different approaches that individuals and corporations can take to meet their goals. It’s really about figuring out what their goals are and then looking at the right type of carbon removal to support.
Ross Kenyon: We should get into this carbon accounting piece of this. I imagine for many people listening, if they’re of a similar generational age, they either had the James Hansen moment or they had Al Gore’s hockey stick moment. There’s probably some other moments I’m missing. For me, mine was An Inconvenient Truth. I think that was the first big climate change thing that happened once I was aware of it. And since probably the beginning, we’ve been taught that the correct way to understand climate action is in terms of tonnage. Offsets are typically denominated in terms of tons, and this is supposed to negate a ton of typically fossil-fuel-based emissions, and you should be buying those on a one-for-one basis.
I’m not sure that that story holds up nearly as tightly as we were taught to, unfortunately. It would be better if it was, because it’s a simple story, and the nuanced story is a lot harder for people to keep in their brain. They’re busy. Where do you think that story has gone wrong? Does it still serve us? How are you thinking about carbon accounting?
Radhika Moolgavkar: Carbon accounting, right. As you take, you offset one emission through some sort of action. Traditionally it was reductions and avoidances. So a company would go out and say, OK, I’m emitting something because I’m trucking, therefore I’m going to go support a clean energy project that, because it’s being built, will reduce the number of emissions, and I can offset that one for one. You know, I think in theory that’s really good, but in practice it became less clear that some of these projects were actually doing what they thought they were doing in terms of emission reduction.
And so it did allow corporates to maybe continue polluting. And I don’t think this was intentional necessarily, but, you know, polluting because they thought they were taking care of a problem in this way, but really they should have been taking care of a problem through emission reduction on their end to truly achieve that. So carbon removal though is different, right, because carbon removal is about a positive action. It’s not about not doing something, it’s about doing something. It’s about removing carbon from the air.
And I think when you think about the story kind of getting more complicated, it’s that how you store that CO2 really depends — really impacts whether you should use it as an offset for an emission, you know, a fossil fuel emission. And so to me the way I understand it best is you want to return the carbon dioxide emission to the place it came from. So if you are tearing up forests and there’s a bunch of soil carbon being released, replanting forests seems like an easy solution because it’s where the carbon came from.
However, if you are doing a fossil fuel emission and it’s coming deep from the ground and it’s in geological storage, then you have to return that carbon back to that storage vessel, if you will. And that’s a lot more complicated, a lot more expensive, and it’s where the vast majority of our emissions obviously come from. Coal, gas, oil — everybody knows that, I think, now. And so I think where it’s broken down is that it is much harder to do than we initially thought. I also think where it becomes difficult is at policy level, and defining these different pathways and how they can be used in context of international, local, federal, you know, policy makes it even harder.
Ross Kenyon: Do people just disagree about the role of carbon removal and offsets at all those different levels, or what makes that so hard to coordinate?
Radhika Moolgavkar: Yeah, I think people disagree. Some people still really believe in nature-based solutions as an emission, I think particularly at the policy level, because there are a lot of incentives and things tied to that. And so people, you know, when money and power start to talk, there’s a lot of competing interests. And I think that’s probably where we’re at. And then you layer onto that the complicated relationships between the Global South and the Global North. And I think it becomes just a very complex human problem, in some ways more than a science problem.
Ross Kenyon: Then there’s also the problem that direct air capture has a lot of technological adjacencies to oil and gas. And so people also are concerned about that intersection. Is that technology that we can trust? Are those intentions pure? Or is that actually a really good thing, that they’re maybe going to run the system in reverse? This is one of the oldest debates in carbon removal. Can you solve it for us right now?
Radhika Moolgavkar: No, I cannot solve it for you, because I think it all depends on your perspective on the oil and gas industry and their role in the future. And, you know, I would not pretend to understand what it’s like to be a community that’s been historically marginalized through these extractive methods. However, oil and gas is part of our world and it’s hard to imagine it ever going away. So I do see the value of bringing them along. But no, I’m not going to solve it.
But I will say that if you can change oil and gas and make them into renewable carbon removal companies, I think it’s a win for everybody, because they do have the skills. They do have the storage. You know, they probably own the storage because they’re former wells and things. And so if you can convince them that better than drilling it up is putting it back in, I don’t think anybody loses in that situation.
Ross Kenyon: It is so extremely challenging to not overwhelm the listener with oodles of adornment here. I think we did a pretty good job. I actually don’t want to add any more right now. I think we should do a series where we introduce more of the complexity here, try and get people up to speed in bite-sized little chunks. So why don’t we just call it there, Radhika?
Radhika Moolgavkar: Sounds good. It is Friday afternoon after all.
Ross Kenyon: Stay tuned for more episodes that will get you up to date on the basics of carbon removal. Thank you so much for listening. If you could please subscribe and give us a great rating and review on Apple Podcasts or a rating on Spotify, that’d be much appreciated. It helps us get our content out to more people. You can sign up for our newsletter at nori.com, follow us on social media, and we will catch you next time.
