In this episode, Host Kristin Hayes talks with Greg Nemet, a professor at the University of Wisconsin-Madison in the La Follette School of Public Affairs and the Nelson Institute's Center for Sustainability and the Global Environment. They discuss the future of carbon dioxide removal from the atmosphere, with a particular focus on negative emissions technologies.
Listen to the Podcast
- “Unlike other environmental problems, just stopping the flow of emissions into the atmosphere doesn’t quite do the job like it might for particulates or acid rain...with climate change, you put [pollutants] up in the atmosphere and they’re there for 100 years. And so there’s no quick fix, even if we took radical efforts to stop the flow of greenhouse gases into the atmosphere.” (5:30)
- “We’re talking about needing tens of billions of tons of removal, so again about 25 percent of what we’re emitting right now, by mid-century.” (18:26)
- “So if we really want to be doing, say, 10 gigatons of removal by mid-century, we need to have these technologies out there on a pretty substantial scale in the next ten years, and that really means starting right now with developing the technologies and starting to test them and looking at some of the side effects.” (18:58)
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The Full Transcript
Kristin Hayes: Hi Greg. Nice to follow up from our conversation at a conference earlier this year. Thank you for joining us at the podcast.
Greg Nemet: Thanks for having me.
Kristin Hayes: So Greg, let's start by introducing you to our listeners. You sit in the public affairs school at the University of Wisconsin, where everyone is apparently extremely productive because it is too cold to go outside.
Greg Nemet: I agree with you. People are very productive here but it's because they are biking to work on the ice and snow and things like that.
Kristin Hayes: Very nice. I will say to you, I have heard Madison is an absolutely lovely city, so whatever February holds is more than made up for by other months of the year.
Greg Nemet: Yeah.
Kristin Hayes: And so at the university you are also affiliated with the environmental studies program. From a quick peruse of your CV, you studied economics and geography as an undergraduate. You studied energy as a graduate student, so you are kind of a disciplinary mutt for lack of a better term.
Greg Nemet: Absolutely.
Kristin Hayes: Can you tell our listeners a bit more about sort of the common threads that run through your research? Or what drew you to those topics that you work on today?
Greg Nemet: Yeah. I mean I think a lot of it is driven by trying to understand how the world works or how things work and trying to work on important problems, and a lot of times you can make an important contribution on important problems by refining a methodology or pushing theory forward or really advancing the state of the art within a discipline. And that's a lot of [...] has made tremendous progress in terms of our society today. But there are these other problems or other aspects of problems where you really need to be pulling different aspects and using different perspectives, different methodologies, and pulling them together.
So, for example, I did a graduate program at Berkeley that included public policy, economics, engineering, and environmental systems—and I really find I draw on all of that on a day-to-day basis, working on energy issues.
Kristin Hayes: Well, that's great that all those disciplines that you've actually invested time in learning are actually coming into play. And I think the topic that we're going to focus on today probably does draw on a lot of those pieces of knowledge as well. So today we're going to be talking about technologies and maybe a little bit about policies involved in carbon dioxide removal, or CDR, as it is sometimes called. Can you start by telling us how CDR is different from some of the other climate strategies that are more frequently talked about, like mitigation or adaptation?
Greg Nemet: Yeah, sure. I mean, the first thing I'd say is “mitigation” in English, that means to make a problem not so bad—but in climate speak, that means something much more specific and it means reducing emissions. But we can also address the climate problem in other ways, and one is by adapting our societies and where we live and how we live, how we move around, to a climate that's going to be different than it is today—and that is adaptation. And another thing we can do is remove greenhouse gases from the atmosphere that are already up there. That's what CDR is about and it's something that really hasn't been discussed in a large and serious way until, I don't know, the last few years. And I think that's for a few reasons. I think, one, people felt that it was a distraction from the hard work of doing mitigation (that is, reducing emissions). And on the other hand it was harder to see why it was needed, but I think those things are changing now and it's becoming taken more seriously.
Kristin Hayes: Yeah. So that's a really good point. I noticed, again, from checking out your publication record that you actually started publishing on this topic in 2012, and I would say that most conversations about CDR were pretty under the radar at that point. So what sort of sparked your interest back then and then why do you think the conversation has gained momentum now?
Greg Nemet: Yeah. So I was living in California in 2005, 2006 when there was a lot of interest. There's a lot of venture capital going into clean tech. There was a lot of [...] “An Inconvenient Truth” had just come out. The Stern Review on climate change had come out. And in 2009, there was a bill that passed the House of Representatives, a cap-and-trade bill. And then the big climax of all of this building up was going to be this Copenhagen Climate Convention in late 2009. President Obama went to that, and a lot of others heads of states. And it really turned out to be a huge disappointment. There was almost no agreement that came out of it.
And so, in the wreckage of 2009, then we had the financial crisis. That climate bill that passed in the House never got voted on in the Senate.
Kristin Hayes: Right, Waxman-Markey.
Greg Nemet: Right. Yeah. And so it really seemed like it just wasn't going to happen. And so I think, for me, I started taking much more seriously these types of approaches to dealing with climate change that can be a bit more reactive. That is, if the problem got a lot worse, or if suddenly there was focusing events like other environmental problems, then we decided we had to get smart and get active about it very quickly. What are the means that we have available? And unlike other environmental problems, just stopping the flow of emissions into the atmosphere, it doesn't quite do the job like it might for particulates or acid rain or others where those pollutants get rained out of the sky within days or weeks.
With climate change, you put them up in the atmosphere and they are there for 100 years, and so there is no quick fix even if we took radical efforts to stop the flow of greenhouse gases into the atmosphere. So, that got me interested in how can we deal with it if we had to react quickly? And so adaptation got taken more seriously. Solar radiation management was another one to start taking seriously. And then carbon removal was another one to start taking seriously. And I guess, as I started looking into that, the one that seemed to have the fewest trade-offs was this direct air capture and that's where I started working on it in 2009, and then we published a paper in 2012 on that. So, yeah, it really got motivated in part by thinking, “Wow, it doesn't look like we're getting our act together in terms of collective action to reduce emissions. What other options are there?”
Kristin Hayes: The mitigation side was looking awfully hard. Yeah. I think that's still played out today, right? At the subnational level, we probably made more progress—but at the national level, you know, we're 10 years out and we still don't have a mitigation policy. So I would say you and your coauthors were definitely ahead of your time on that one.
Greg Nemet: It can be frustrating to see and to think, to weigh, you know, we've known around this problem for quite a long time. I think the world knew about it in a serious way in the late 1980s, 1990s, and the Rio Convention 1992. So in a way, we've been dithering for 30 years on trying to do something about it. But I do think that there have been things happening in the background that actually make the problem more solvable and more close to doing something compared to 5 or 10 years ago. So I do think there is a way in which we haven't just been wasting our time, even though we have been doing that. There have been some positive things that have been happening as well. But there's also a much stronger urgency to do something about it as we see time go by, and the science saying, it's very rare to get a study saying, “oh, it's these impacts or these feedback effects that are going to be less intense than we thought they might be. It's actually not that bad.” We almost never see news that way.
Kristin Hayes: Right, right. So, I am going to throw this question in here and maybe we can come back to this later too, but I am curious: you've talked a little bit about mitigation and adaptation and of course carbon dioxide removal. Do you see these strategies as complementary? Are they substitutes for each other? In your view, is it really that we're going to need an all-of-the-above approach at this point?
Greg Nemet: Yeah—all of the above. I think they are really complements to each other. And I think any one of them on its own is just a disaster that's not going to work. So, just reducing emissions, we still need to do adaptation. We can't just protect ourselves by building sea walls and adapting the climate—that'll be insufficient. We can't just invest or rely on putting mirrors up in space to block sunlight. That's not going to do it either. And even carbon removal itself has limits to how much we can do, and I think there are also limits to how much we want to do. So any of these things, when we do it at a massive scale, which we'll have to do anyway, but if we were to rely on only one of those kinds of levers, it will be an even larger scale. And so all of them have side effects and negative impacts and those will be larger at larger scale, so yeah. I definitely see adaptation, geoengineering, mitigation, and carbon removal as complementary strategies. All of the above, as you say.
Kristin Hayes: Okay. Well good. Let's talk a little bit then about some of the specific carbon dioxide removal options that are out there. And they seem to fall into a couple of different buckets. There are some natural solutions, some ones that might be more focused on technology, and then ones that are a bit of a hybrid, where you might actually use technology to enhance a natural solution to actually sequester more CO2. So, yeah. Can you tell us a little bit more about the wealth of options that are out there and that you've looked at?
Greg Nemet: Yeah. There are quite a few and some of them will be very familiar to people, and some will seem quite exotic. So, one that I'd start with, maybe, is planting trees. So you can store a lot of carbon—
Kristin Hayes: A classic choice.
Greg Nemet: Yeah. In plants and in the wood of trees, and we do a lot of that already. And so by growing more forests and reforesting places that have been deforested, we can store more carbon in those trees and that is appealing I guess for some pretty obvious reasons. So it doesn't necessarily have to be very expensive. It's not something we have to prove that we know how to do. So that's a very appealing strategy to a lot of people. But, like any of these strategies, it has downsides as well. So, for example, just planting lots of trees, to me, the biggest issue is land use. If that's land that had been used for grazing or for agriculture, then you're competing with food—and if you plant trees there, that would increase food prices and that's important because one of the biggest concerns people have about the impacts of climate change is declining crop yields and food insecurity and food prices that could go up as a result of that. So we definitely don't want to—
Kristin Hayes: Right, you don't want to exacerbate that. Yeah.
Greg Nemet: Yeah. We don't want a solution that is causing a problem that we are worried about. The other issue with trees is permanence, too. So the CO2 gets stored in those trees, but you have to keep rotating them because the trees will eventually die and decompose. But also, if you decide to change your mind about storing them in those trees, then you have a release as well. So the permanence is reversible, unlike some of the other ones.
Kristin Hayes: Right. Okay. And is there something [...] is there a sense of scale to be thinking about when it comes to afforestation—to actually adding more trees as well? I think, my understanding is that there have been studies that look at how much of the Earth's surface you would need to reforest or afforest to really deal with carbon dioxide removal just through trees, and it's basically impossible. You'd have to plant forests over all cities and things like that. So is there a sense of scale that also matters?
Greg Nemet: Yeah. So we definitely couldn't do only trees. Maybe to put it in perspective a little bit, so we're putting about 40 gigatons of CO2 into the atmosphere every year. And that's every year we're doing that—we're adding more and more. If you look at some of the scenarios about trying to stay at 2 degrees or less, we're talking about needing to remove about a quarter of what we're emitting today. So about 10 gigatons of CO2 per year. And when we did this study last year, the highest estimate we could get for how much CO2 you could remove from trees is about three and a half gigatons of CO2. So that's maybe a third of what we need to remove, but that's with doing as much mitigation as we already can.
So we're not talking about solving the problem with trees, but it could be an important part of it.
Kristin Hayes: Sure, yeah. And as you mentioned at the beginning, I don't want to be too dismissive of it either because it has other co-benefits that we might want to embrace but also challenges. So that's really helpful—I am glad you had those numbers at the tip of your tongue. It's always great to have that perspective. Okay. What other options are out there?
Greg Nemet: Another one, and this is maybe more of a hybrid of a natural plus an industrial process, where you could create bioenergy growing crops, using crop waste—things that use photosynthesis to take CO2 out of the air and turn it into some kind of plant material. Then you take that plant material and you burn it. And as you burn it, just like burning coal or something, you create heat and you can make electricity or use that heat. And so you have useful energy that comes out of burning those crops. Then, if you add another process, which is where you capture the carbon dioxide that's in the flue gas that comes out of that burning, compress it, move it to somewhere, and then pump it underground—then you are actually net taking CO2 out of the atmosphere, putting it into plants. And then taking that CO2 and putting it underground, and you are making energy. And that has a lot of people excited because it's natural in that you are using photosynthesis. It's productive in that you are creating electricity or heat energy. And then you have this permanent storage when you put it underground. So that has a lot of appeal and that sometimes comes under the jargon-y acronym of bioenergy with carbon capture and storage or BECCS.
Kristin Hayes: BECCS. Yep—okay. My understanding is that also has [...] it has advocates, of course, but there's a fair amount of push-back. Is that also for some of the reasons that you mentioned related to food security and that sort of—
Greg Nemet: Yeah. And even more because you're trying to have high yields to get a lot of crops to put into your power plant, and so you actually need pretty productive land to make those crops and so it's competing with food there. It's an industrial process, so we're talking about making power plants there and then you have to store that CO2 somewhere as well. But I think, if I would focus on one thing, I think it's this food-fuel competition that I think is a real issue with BECCS.
Kristin Hayes: Okay. All right.
Greg Nemet: And then another one, I'm just trying to [...] there are others as well, but just to kind of expand the range of possibilities from ones that are pretty natural to ones that are kind of a combination of natural with an industrial process to ones that are just purely industrial. And I would say direct air capture fits into that last category. So that's doing what we've done for 80 years in submarines, or 60 years in spacecraft, which is to remove the CO2 that gets exhaled by humans and scrub it out or absorb it—and then capture it and then put it somewhere else.
So you could take that same idea, similar technology, and absorb CO2 that's in the atmosphere, capture it, bind it onto a contactor, and then heat it up and release that CO2—and then do what we did with BECCS, which is to compress it and move it away and transport it and then pump it underground and store it permanently, just like with BECCS. So that's interesting. To me, mainly, it doesn't have that main side effect that forests and BECCS have, which is—it's not competing with food and it's not competing with land. It really does not take a big land footprint. It's kind of similar to maybe how a wind turbine [...] you see it, but it's not taking up a lot of space and so you can have crops and grazing and other activities right next to it, and that can be similar for direct air capture. The biggest issue—and it's been kind of dismissed for the last 10 years or so—is that it's just impossibly expensive, at least that was the thinking.
And there was an estimate by the American Physical Society of about $600 per ton of CO2, and that's—that’s really expensive compared to the price of CO2 in Europe, now, is in the mid to high 20s and the average price for the whole world is something like $5 per ton of CO2. So they would be talking about $600—seems impossible. But there are a few entrepreneurs and companies that didn't really listen to that report and just started trying to develop the technology on their own. And there's three of them now and they're starting to actually build plants that are actually doing this in a real way, and someone is using the CO2. In some cases, they are storing it. But those plants look like they are more in the neighborhood of maybe $200 per ton of CO2. And there's a pretty convincing pathway to get down to $100 per ton of CO2. And if you are at $100 per ton of CO2, then I think we're in business. Then I think we're kind of around the willingness-to-pay that people have to deal with this problem.
So that's pretty interesting to see how that technology is developing.
Kristin Hayes: Yeah. So it sounds like there are a number of options out there across the natural-technological range. One thing that I've thought about as these options have been described is, how are we going to know how much to invest in which ones? That's a bit of a ridiculous question because obviously we're going to have to make some choices. There's not going to be a perfect answer out there. But if you were a policymaker or an investor in technology, how would you begin to decide which of these solutions to implement to what degree, and perhaps where, as well?
Greg Nemet: Yeah. I mean, I guess my thinking on it is similar to before with this idea of having a portfolio of mitigation, carbon removal, adaptation. Maybe some geoengineering as a backup plan. Even within carbon removal, I think we're going to be best off if we’ve got multiple solutions in place—because they all have downsides and some of them could actually be nice to have a portfolio of these different options. Some of them work better in different parts of the world. Places where there is land available, you might do the land-intensive parts. So I like to have many options at our disposal, but we don't have an unlimited budget and this is an expensive problem.
I guess the other aspect of that that I would introduce at this point, too, is we're talking about needing tens of billions of tons of removal. So, again, about 25 percent of what we're emitting right now by midcentury. And so that seems quite distant. But if you look at other technologies and how long it takes to scale up and you have them widely adopted—that means we actually really have to get started very soon on starting to prove some of these technologies, build pilot plants, and then start to scale them up pretty quickly after that. So if we really want to be doing, say, 10 gigatons of removal by midcentury, we need to have these technologies out there on a pretty substantial scale in the next 10 years. And that really means starting right now with developing the technologies and starting to test them and looking at some of the side effects and deploying them in demonstration plants.
So, I guess, policy-wise or strategy-wise, I would think the next 10 years is the time to, in part, experiment; in part, learn; and, in part, do some early deployments of all of these carbon removal technologies so that we can see what works, what can be improved, which ones seem like they are getting better, which ones seem like they have side effects, they’re just intolerable. I think there's a lot to learn from doing some of that work so that we can say in 2030—we can start to get really serious on deploying maybe a narrower set of them. So I think it's really the time for a broad portfolio of carbon removal programs to go forward.
Kristin Hayes: A little bit of experimentation. Yeah, and if I'm not mistaken, the companies that have already started investing—particularly in the direct air capture side—are mostly European? I think there's one in Switzerland? Perhaps other places in Europe?
Greg Nemet: There's one in Switzerland. There's one in the US and there's one in Canada.
Kristin Hayes: Oh great. Okay.
Greg Nemet: So it's relatively distributed and each of them has a real working example where there's a real customer for the CO2. And I think that's a really big advance compared to where we were a couple years ago. But just to put it into perspective, they need to be growing really quickly. They need to be growing—like, doubling—their production every year or so. And right now, if you put all those companies together, I think, my estimate is there's about between 200 or 300 people in the world that are employed by air capture companies, and that's just not aligned with the—
Kristin Hayes: Yeah, that's pretty small.
Greg Nemet: —to deal with the scale of the problem. It's promising to see those companies, but they need to scale up.
Kristin Hayes: Yeah. And so you mentioned customers as well. That's an interesting piece of the economics of this. So, obviously, if there's a use for the CO2, if they can actually recoup some of the costs and sell that to someone else who can use the CO2, that does change the economic picture just slightly. What are some of the uses? And if a customer can't be identified for whatever reason, what does it look like for storage without that customer base in place, if that makes any sense?
Greg Nemet: Yeah—I mean, I think what a lot of people are waiting for or looking for is a policy signal that would put a price on CO2 and maybe a price on emissions. And, presumably, would include some kind of credit if you were to remove CO2 from the atmosphere. So some kind of tax or cap-and-trade program that gives credit to capturing carbon would put a lot of these things in the money, depending on what that price is. But in the meantime, it's helpful if there are other markets that aren't quite as sensitive to the vagaries of elections or what Congress decides or what other countries decide to do. Those can change a lot and they've proven to be very volatile. And even when you do have a system in place, the prices seem to go up and down very quickly, like we've seen in the EU. And so it can be quite risky for companies to bet everything on a policy like that.
So, what these three companies that I mentioned are quite savvy [in] is, they are looking for niche markets. So customers that'll pay for CO2 today, regardless of policy. So, one place that you pay for CO2 is making beverages. It's not a gigaton-a-year market, but it's enough—and some of the prices are high enough and there's a range of prices that you could justify building a plant to remove CO2 from the atmosphere, create pure CO2, and then put it into beverages.
Kristin Hayes: Yeah. Are there other product uses? Are there, sort of, pie-in-the-sky product uses that people are talking about?
Greg Nemet: Well, I mean, the other ones that I guess are less pie-in-the-sky are just ones that are real right now. So there’s using it for beverages. There's also using it for greenhouses. So, that company in Switzerland, their first plant was to increase the amount of CO2 in the air in the greenhouse by about 50 percent, which would increase the crop yields of peppers and tomatoes that were being grown there. So that's an example of it. Another way to do it is pumping CO2 into old oil fields.
Kristin Hayes: Of course—enhanced oil recovery. Yep.
Greg Nemet: Yeah, being able to get more oil out of that. And for a lot of these examples, they are not actually removing [...] they are removing CO2, but they are putting it back into the atmosphere, and so these aren't solutions to the climate problem. But they are solutions to demonstrating the technology, building real companies, dealing with real customers, building infrastructure, building a supply chain, and scaling up. So I really do find it encouraging that there are these markets that aren't completely dependent on policy—even though in the longer term (and that's not maybe not that long from now), to do gigaton scale, you do need to have a policy signal and a price.
Kristin Hayes: Okay. Yeah. Again that complementarity between a mitigation policy or a broad-ranging policy that includes mitigation but also gives signals to CDR.
Greg Nemet: Yeah.
Kristin Hayes: So, two more questions for you about this topic. I feel like I could ask you many questions. But I guess I've been thinking about—in thinking a little bit more about this topic before the podcast, certainly there are concentration targets that have been laid out in various scientific reports, that we might want to get to an atmosphere that only [...] that sort of levels-off at 350 ppm [parts per million] of CO2. And certainly that number did not come out of nowhere and, yet, it is one number—and of course the world would continue to exist at various levels of CO2 in the atmosphere. So, how do you see policymakers or technologists being able to decide what the right level of CO2 is and, therefore, where to sort of [...]. Let's say in a magic universe 50 years in the future, where we are pulling substantial amounts of CO2 out of the atmosphere: How do we know when to stop? Particularly if these are now [...] if the technology's actually driving industries and jobs—how do we say, “right, nope we're good? We've pulled enough out. We're at 350 ppm. We're going to stop here?”
I think that would be a really good problem to have.
Fair enough. Fair enough.
Greg Nemet: Yeah. I guess there are concerns about who gets to decide about what the right level of CO2 in the atmosphere is. And I guess maybe my view is a little more short term (which means more like the next several decades), where the downside of going to 1,000 parts per million or 1,200 or something like that is tremendously negative—and also completely feasible and completely possible to think about. And so thinking about ways to avoid 1,200 and get down to whatever it is, half of that, 500 or 400, yeah. I guess, to me, the less the better—but, yeah, I guess at some point, you do have to think about what the long-term equilibrium would be. And I guess I don't see that as a problem right now, but it could be at some point.
Kristin Hayes: Yeah. That makes a lot of sense and I can definitely understand that you wouldn't want to let any future management challenges sort of stop you from getting the technology up and running now. So, yeah, thanks. And just another pushback that I've occasionally heard in the discussions around CDR is sort of back to a topic that we touched on at the very beginning, which is a concern that some people have that—if CDRs, in fact, viable and sort of regularly available as an option, that it just sort of perversely allows emitters (and, in many ways, that's all of us) to just keep pumping CO2 into the atmosphere. So it sort of allows us to not have to consider any of the perhaps more challenging behavioral change aspects. What's your take on that criticism?
Greg Nemet: Yeah. I don't think there's that much carbon removal potential available. So if we're doing, like, 40 gigatons of CO2 in the atmosphere every year now and, you know, could potentially double that if we don't [...] if we continue in our ways, to something like 80. When we did this assessment, we think there's a potential carbon removal of something like—something around 10 gigatons a year. So there's no way we're going to offset putting 50 or 60 or 70 gigatons of CO2 in the atmosphere with what we think there's available for carbon removal. They don't really match up. It's really just a complement. It's just part of the solution. I guess there's just concern that people are using this as a reason not to do mitigation and, I don't know, I don't quite see that argument because we've been [...] knowing we needed to do emissions reductions for 30 years, and we really have not made a lot of movement on it. Some countries have, to give them credit, but from an overall global scheme (which is what matters), we really haven't. And so to say that it was having carbon removal available that's led us to not do anything, that wasn't really an option.
So I don't really see that as the reason. And to say that that's the reason now, I think [..]. I don't think that's really what's driving people. So yeah, I really think of it more like an insurance policy. Probably one that we're going to need, but one that's going to help us avoid some of the worst-case scenarios. And so it may be that when you have an insurance policy, there is some moral hazard. And if you have fire insurance, you're a little bit less careful with fire in your house. But it's still your house, and you still don't want it to catch on fire. And so it's worth it, having the insurance even if there is some difference in behavior that happens. I guess that's how I look at carbon removal. It's something that we need and if it skews our incentives a little bit to emit more, it's worth it. That's not a reason not to do it.
Kristin Hayes: Mm-hmm [affirmative]. That's very helpful. So, Greg, we are pretty much at the end of our time here. And so I guess I better close with our regular ending feature, which is called “Top of the Stack.” In this segment, we ask our guests to recommend some more good content. A book, an article, a podcast, a movie—so, Greg, what's on the top of your stack? And if there are recommendations that you want to make for your own research? I know you've mentioned an assessment that you guys have done, we can certainly put in a link to that. But if there's anything sort of broader or outside of your own work that you'd want to recommend, too, we'd love to hear it.
Greg Nemet: I've really had my head down the last several months, trying to finish a book that's coming out later this spring or early summer. But it is relevant to what we're talking about here. It's a book looking at the evolution of solar PV [photovoltaic] technology and how it became so inexpensive, and then thinking about how some of the lessons from that could be applied to carbon removal technologies or other mitigation technologies. So that's really what's been my focus the last several months and I am hoping to have more to show about that when the book comes out in the next few months.
Kristin Hayes: Okay—great, great. Do you have a working title for us so we can—
Greg Nemet: Yeah, the title is How Solar Became Cheap. And it's a model for low-carbon innovation.
Kristin Hayes: Okay, fantastic. Greg, thank you so much for joining us today. This is obviously a topic that, I would say, continues to get an increasing amount of attention so it's nice to have a grounding in it from an expert.
Greg Nemet: Great. Thank you. I really enjoyed your questions and really enjoy your podcast as well.
Kristin Hayes: Great.