HKS Professor and physicist David Keith, who works at the intersection of policy and climate science, says cooling the planet as we continue to reduce emissions is increasingly becoming a matter of ethics as well as science.
Featuring David Keith
novembeR 2, 2021
30 minutes and 59 seconds
Leaders from around the globe are meeting in Scotland today for the COP26 summit, talking about ways to speed up efforts to fight global warming. Yet even the optimists in Glasgow admit that the scientific consensus is that it’s already too late to cut emissions fast enough to avoid a dangerous rise in the earth’s temperature by 2 degrees Celsius, which is expected to lead to severe droughts, blistering heat waves, deadly flooding, and rising seas.
Despite these dire predictions, there has been one potential weapon in humanity’s anti-warming arsenal that, in terms of practical research, has been a taboo subject: solar geoengineering. Now Professor David Keith says it’s time for that to change. Keith is an award-winning physicist who holds professorships at both Harvard Kennedy School and Harvard’s School of Engineering and Applied Sciences. Working at the intersection of physics and policy, Keith is a pioneer in the field, which involves making man-made changes to the atmosphere to cool the planet by either preventing some of the sun’s energy from getting through, or making it easier for heat already in the atmosphere to escape.
Critics have had a tough time wrapping their heads around solar geoengineering. They call it the stuff of science fiction, say it could be used as an excuse not to further cut emissions, and even suggest that governments might someday use it as a weapon. But Keith says that it’s now time to explore it as one of major strategies to fight warming, which include cutting emissions, capturing the carbon that’s already in the atmosphere, and helping people and societies adapt to the effects already being felt. One of his primary arguments for starting serious research on cooling the earth is inequality. After all, he says, planetary warming doesn’t play fair. It is mostly people in the world’s poorest countries who will suffer the worst harm from a warming climate, yet they are the least responsible for it in terms of per capita emissions. And amid all the recent talk of climate adaptation, there is comparatively little mention that it is much easier for a rich country in a colder latitude to adapt than it is for a developing one in a hotter region.
Keith is also known for his work on carbon capture and founded a company working on technology to pull carbon from the air—although he says that is at best a long-term strategy that could take decades to have any beneficial effect.
About the “Systems Failure” Series:
To kick off the fall 2021 season, we have launched a mini-series of episodes built around a theme we’re calling “Systems Failure.” Our conversations focus on how the economic, technological, and other systems that play a vital role in determining how we live our lives can not only treat individuals and groups of people unequally, but can also exacerbate inequality more generally in society. We also talk about strategies to change those systems to make them more equitable.
David Keith has worked near the interface between climate science, energy technology, and public policy for twenty five years. He took first prize in Canada's national physics prize exam, won MIT's prize for excellence in experimental physics, and was one of TIME magazine's Heroes of the Environment. Best known for work on solar geoengineering, David’s analytical work has ranged from the climatic impacts of large-scale wind power to an early critique of the prospects for hydrogen fuel. David is Professor of Applied Physics in the School of Engineering and Applied Sciences and Professor of Public Policy in the Harvard Kennedy School. He spends about a third of his time in Calgary, Canada where he helps lead Carbon Engineering, a company developing technology to capture CO2 from ambient air.
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David Keith (intro): So, if you're hotter when you are learning as a child, you learn less well, you do less well on tests and you are less economically productive 30 years later, there's actually a really beautiful study that shows that, so I'd say, in total, there's this very strong evidence that heat is a big driver of overall climate impacts. And it's clear that the impacts of heat are much worse for places that are already pretty hot. And in fact, there may be benefits for places that are cold, and most of the world's poor are living in places that are hot, not exclusively, of course. And so that's the central reason why climate is expected to be very regressive: that the impacts of climate change hurt the poor on average, more than they hurt the rich.
Ralph Ranalli (intro): Welcome to PolicyCast and the third and final installment of our Systems Failure Series. I’m your host, Ralph Ranalli. In recent episodes, we’ve examined both technology and the economy as examples of systems that play a huge role in determining how we live, but that also contribute to inequality and other society harms.
Today we turn to climate, which, since it holds the key to humanity’s future as a species, is arguably our most vital system of all . Right now, leaders from around the globe are meeting in Scotland for the COP26 summit, talking about ways to speed up efforts to fight global warming. Yet even the optimists in Scotland admit that the scientific consensus is that it’s already too late to cut emissions fast enough to avoid a dangerous rise in the earth’s temperature by 2 degrees Celsius, which is expected to lead to severe droughts, blistering heat waves, deadly flooding, and rising seas.
Despite these dire predictions, there has been one potential weapon in humanity’s anti-warming arsenal that even in terms of practical research, has been a taboo subject. But Professor David Keith says it’s time for that to change. Keith is an award-winning physicist who holds professorships at both Harvard Kennedy School and Harvard’s School of Engineering and Applied Sciences. Working at the intersection of physics and policy, he is perhaps best known for his work in solar geoengineering, which is the science of making man-made changes to the atmosphere that would cool the planet by either preventing some of the sun’s energy from getting through, or making it easier for heat already in the atmosphere to escape.
Critics have had a tough time wrapping their heads around solar geoengineering, calling it the stuff of science fiction, saying it could be used as an excuse not to further cut emissions, and even that governments might use it as a weapon. But Keith says that it’s now time to explore four major strategies to fight warming, including cutting emissions, helping people and societies adapt to the effects already being felt, and solar geoengineering. Keith is also known for his work in the fourth strategy, carbon capture, and founded a company working on technology to pull carbon out of the air — although he says it is at best a long-term strategy that could take decades to have any beneficial effect.
So what does any of this have to do with inequality? Well, Keith says it is one of the primary arguments for starting serious research on solar geoengineering. After all, he says, planetary warming doesn’t play fair. It is mostly people the world’s poorest countries who will suffer the worst harm from a warming climate, yet they are the least responsible for it in terms of per capita emissions. And amid all the recent talk of climate adaptation, there is comparatively little mention that it is much easier for a rich country in a colder latitude to adapt than it is for a developing one in a hotter region.
It’s a complicated subject, but an important one. Professor David Keith is here to help us sort it out.
Ralph Ranalli: David, welcome to PolicyCast.
David Keith: Thanks. Thanks for having me, good to be here.
Ralph Ranalli: With any scientific discussion, it's probably best to start with definitions. So, can you lay the foundation for us by talking a bit about what solar geoengineering is? And you're advocating for researching it, as a potential solution or palliative to climate change, broadly speaking. I think many people know that it's about making intentional man-made changes to the atmosphere to counteract global warming, but can you talk a little bit more about specifically what it is?
David Keith: The core idea is that humans could deliberately make the earth a little bit more reflective, so it absorbs a little bit less sunlight. And when you think about this, the central thing that's causing climate change is the buildup of greenhouse gases like carbon dioxide in the atmosphere, and that makes it harder for the Earth to radiate away heat, and at some level you can think of the climate as a balance between how easy or hard is to radiate away heat and how much heat, or energy the Earth absorbs from the sun. And so if you've warmed the planet up and changed the climate by adding carbon dioxide, you could at least reduce some of the changes by reducing the amount of sun that was absorbed a little bit. The best way to understand it, is to think about it, in relation to the other things we can do about climate.
And, in my view at the very top level, there are four fundamental things to do. One is to reduce emissions, the emissions that are causing the build up of greenhouse gases in the atmosphere by changing the industrial basis of our civilization. The second one is to remove carbon dioxide from the atmosphere, the third one is this Solar Geoengineering, or climate intervention, or whatever you want to call it, and the fourth one are local adaptive measures that reduce the amount of suffering or ecological damage for a given amount of climate change. So very broadly, I think you should see solar geoengineering as one of those four things that are potential ways to reduce. The only one of those that we clearly have to do is to cut emissions, the other ones are choices.
Ralph Ranalli: Obviously with COP26 going on we're talking a lot around the world about cutting emissions. But in terms of Solar Geoengineering, you’re advocating for seriously researching it as part of the overall effort against warming. Would you say that we're moving from a scientific conversation about geoengineering towards a more practical conversation about policy?
David Keith: Yeah, I wouldn't say that. So I would say this never was really a purely scientific conversation. Science is about understanding how nature works better, and Solar Geoengineering is not a question of science, it's a question of technology—ultimately of engineering. It's a question of applying scientific knowledge and engineering knowledge to do something. And from the very first discussions of these technologies in the 1960s, they were framed as potential things to do, to reduce the harms from climate change. So, that's not a scientific question, it's a question about the potential development of use of a technology, very different from science.
Ralph Ranalli: Can you walk us through some specifics about the technologies of Solar Geoengineering? I understand that different techniques try to affect different layers of the atmosphere.
David Keith: So, maybe from the top, literally the highest place to the lowest place, there's a big range of ways that humans might do this, humans might alter the Earth's energy balance. So, from the highest, it's at least conceptually possible to put huge reflective screens in space that would reflect some sunlight before it got to the earth. I think that's kind of laughable in the next decades, but this is a 150 year or so problem. And I think it's not crazy to imagine that humans could do that late this century. The second way, going down, is to add aerosols, fine particles that reflect sunlight into the upper atmosphere, the stratosphere, which is about, in the tropics, about twice as high as a conventional aircraft flies above our heads. And, the reason that people focus on the stratosphere is that materials stay there for about two years.
Ralph Ranalli: And that's, that one is basically creating a man-made version of the after-effects of a big volcanic eruption, right?
David Keith: Some volcanoes put sulfur dioxide in the stratosphere, which makes fine aerosols, which does cool the planet globally. So certainly part of it is based on that. Yes, so you can think of it as a deliberate analog to that natural phenomena. And then moving down, there's possibilities for reducing certain kinds of cirrus clouds, and then further down, it's possible to make some lower-level clouds whiter, or to make the surface brighter.
Ralph Ranalli: So the subtractive version of this—which is when you're talking about breaking up the cirrus clouds in the troposphere—what does that do for us?
David Keith: So that actually does something a little bit different, at least partly. It makes it easier for the infrared light to get out rather than reflecting more of the solar light. That, of course, it actually does a little bit of both, and so at least in principle, that could actually be better in compensating for the damage of carbon dioxide. But it's deeply uncertain whether it works at all, or what areas it would work in.
Ralph Ranalli: This podcast is part of a series that we're calling Systems Failure, and it's about the systems that affect how we live our lives and how they can contribute to inequality. Now climate is arguably the most important system that affects our lives, but you've said that inequality is also a fundamental issue here in regards to the climate crisis and that these strategies, including solar geoengineering, can address that inequality. Why do you say that?
David Keith: Yeah. I mean, let's start with inequality. I mean, one of the really amazing things that has come out of the literature on climate change in the last decade, or so is actually coming from applied econometrics is really a quantitative understanding of how heat impacts people. It shouldn't have been a surprise, but there's now really strong evidence that high temperatures obviously kill people in heat waves, but they also reduce intellectual and physical productivity. You can see that as reduced economic productivity. So on a hot year, the GDP grows less in India, say than on a cooler year. And, that's true in general, in most countries, that are not the coolest countries. So a warmer year in Sweden or Canada, that can actually make economic growth slightly larger.
And, it's clear that some of this is a long term effect, as an economist we think about it maybe as an accumulation of intellectual capital, and heat can reduce that. So, if you're hotter when you are learning as a child, you learn less well, you do less well on tests and you are less economically productive 30 years later, there's actually a really beautiful study that shows that, so I'd say, in total, there's this very strong evidence that heat is a big driver of overall climate impacts. And it's clear that the impacts of heat are much worse for places that are already pretty hot. And in fact, it may benefit places that are cold, and most of the world's poor are living in places that are hot. Not exclusively, of course. And so that's the central reason why climate is expected to be very regressive: that the impacts of climate change hurt the poor on average, more than they hurt the rich.
Ralph Ranalli: I can remember 30 years ago, when we were talking about reducing carbon, we talked about having this comparatively long runway where we had a chance to reduce admissions and really affect climate change. And I’m struck now by the fact that now we’re talking so much about adapting to warming now rather than preventing it. And it seems like the same fundamental unfairness applies there too, since your ability to adapt is really a product of where you live. It's just a lot easier to adapt when you're in a rich country in a colder region.
David Keith: For sure. I do want to take issue with this sort of assumption that our opportunity or the benefit for cutting emissions was bigger then, and somehow we've lost our chance. I think obviously many of us feel we ought to have done much more decades ago, but it's still absolutely imperative to cut emissions. And it's still true that cutting emissions will reduce the growth of the underlying thing that causes climate damage and so will make the future better off.
Ralph Ranalli: Let's talk about some of the arguments against Solar Geoengineering, because there seemed to be a lot of them. The first one being that, to some people, it just seems like it's science fiction, it's too much for them to wrap their heads around. But you've said that what's been in the popular media a lot of the time about Solar Geoengineering just isn't based on science. Where are we in terms of the state of the science on this? What does the science we have actually say?
David Keith: So, for stratospheric aerosols, which are the thing, the methods, best understood, there's, depending on how you measure it, sort of half a century of science, of understanding aerosols in the atmosphere and in the stratosphere with measurements, understanding of stratospheric circulation, understanding how the aerosols form. Of course, there's 101 uncertainties, but there's now a deep body of knowledge. And my view is that we can say with very high confidence that, if you add aerosols to the stratosphere, you will reflect sunlight, and the planet would cool. Nobody would seriously doubt that. There are, of course, a bunch of questions about the details of side effects, so if you're adding caponization acid, would it cause acid rain, would it damage the ozone layer, how even would it be? There are a big range of those questions, but for each of those questions, despite the fact that there's been basically a taboo against research on Solar Geoengineering, because those questions are tightly tied to questions people have been addressing environmental and atmospheric science, there's significant bodies of knowledge. So I don't want to sound like we know everything. We never will know everything, even after this is deployed, we won't know exactly how well it worked or didn't, but there is a pretty deep body of knowledge that actually can give some confidence about some views of what would happen. And there's also the engineering ability to put materials in the stratosphere. So, I think the crude ability to actually deploy these technologies is sort of fundamentally there, in the sense that it could be done with adaptation of commercial technologies—what is often called commercial off the shelf.
Ralph Ranalli: So, one of the other arguments against geoengineering is sort of this addiction argument. The idea that if we use it and it works, we become dependent on it and stop doing the other necessary stuff like cutting emissions. But you use the analogy of a medical opioid, in the sense that yes you can get this really bad unintended consequence if you misuse it, but if used properly and with care, it really can alleviate a lot of pain and suffering.
David Keith: Yeah. I think that's by far the most important argument against, and the argument that I take most seriously. I think it’s an argument that could be used to make a case that there really should be a permanent ban on deployment. The argument is really about what some have thought of as risk compensation, about the idea that if you have something that provides a partial short-term fix that masks a long-term accumulative problem, and if you use that partial short-term fix and stop dealing with the cumulative problem, you actually make yourself worse off. And that's true. You can think of individual examples and it's certainly true globally.
So if solar geoengineering was deployed as a straight substitute for cutting emissions—if we said we're just going to keep the planet cool with solar geoengineering and party on with fossil fuels—it is certain that the world gets to a more and more dangerous place because the carbon concentration of the atmosphere would keep growing. The underlying risk would keep getting higher and, at some point, disaster would be inevitable. But I think to argue that because there's some potential risk compensation we shouldn't look at a technology, I think that's not reasonable, and I think it's not ethical when you think about who benefits, and who loses.
So maybe I'll go at this in two ways. One is to say it's by no means obvious how the introduction of these potentially masking technologies does or doesn't tie together with the acceleration of dealing with underlying problem. In the almost 60 years since I was born, the deaths per lane mile in the U.S in automobile accidents are down by roughly a factor of five. And that's due to this whole matrix of things from you having much better control over people driving drunk, to changes in cars, changes in roads, changes in licensing. And, there's some evidence that the changes actually were synergistic. So, there were people who argued strongly in print against introducing airbags because of risk compensation. The argument was just let people drive more dangerously and perhaps some risk compensation actually did occur, I guess, as it did, but still in a sense, this set of solutions fitting together, made people more confident that they really could drive automobile deaths down and I think built a social credibility to efforts to do that.
And coming much closer to climate there were people such as Al Gore, who used to argue very strenuously that we should not talk about any adaptive measures like local measures to reduce the impacts of heat waves because it would inevitably distract from efforts to cut emissions. So first of all, I just think that's just plain unethical because the people who die in heat waves are going to be poor and they're doing it in the short run mostly, and the benefits of reducing emissions mostly go to the long run. So there's a real ethical questions about that. Second of all, empirically, what we've seen in the last 15 years, there's now much greater focus on cutting emissions than there was, albeit much less actually being done than I would like, and at the same time there's much more focus on these adaptive measures which now often called climate resiliency. And so clearly it is possible to walk and chew gum at the same time, to make some real progress on cutting emissions—not as much as I would like—and to make progress on adaptive measures.
Ralph Ranalli: I think you could also make a counterargument around what happens when you put on your seatbelt. Each time you click it, you become momentarily aware that an accident is potentially waiting for you out there and that you should drive with care. And I don’t know if you’re going to agree with this characterization, but if we’ve got no choice but to make this Hail Mary pass on climate that involves making man-made changes to the atmosphere, that fact alone could get people more focused on other important measures like reducing greenhouse gases.
David Keith: I think, that's right. I don't love the Hail Mary analogy because it has this kind of binary, "catch the pass or you don't", which is exactly what climate isn't like. It's all these cumulative risks. But to your core point, I very much agree. I think that it is possible that the fact that humans talk about, or actually do deploy, something which is clearly a high-risk technology with big consequences may actually increase the focus on the need to cut emissions. And they are analogs where it's clear that has been true.
Ralph Ranalli: Another counter argument is weaponizing, meaning that you could somehow take these Solar Geoengineering technologies, deploy them in a local way with bad intent towards your enemy, and then you have this escalating war in the atmosphere. You've said you're not really worried about that. Why not?
David Keith: Yeah. I would really defend that. I think that it's not that I'm naive about intentions. I think it's really obvious that humans wanting to fight each other with malice will look to almost any technology to exploit it for harm. But the technologies that people tend to use for weapons sort of tend to have a focused effect, so mostly effect is in one place. And they tend to act quickly. In fact, there's really a reason to believe that we've seen this big movement in military use of force over the last decades to be more and more precise. And these changes in climate … climate is by definition a slow moving thing. the changes are slow and inherently cannot be localized. You could localize the deployment, but you can't localize the effect, these non-local interactions. So the fact that it's inherently slow moving means it's hard to even detect the effect and it's not local, so I think makes it really profoundly useless as a weapon.
And, so when I've been involved in this kind of brainstorming with people from the military, in thinking about it it's just really hard to see that there's a practical scenario. So I think weaponization—there's a kind of natural fear of this and some talk about it. I think it's healthy that people are worried about it to be clear, but as soon as you go one level deep and actually start to talk about credible scenarios, it's really hard to think of any. I think that's kind of luck, it's not good intentions, but it just happens that the technologies that are most feasible for Solar Geoengineering—which is really stratospheric aerosols—are most useless as a weapon because stratospheric aerosols sort of last for two years and spread at least over one hemisphere. And so there's just not an ability to target the effect.
Ralph Ranalli: Let's turn for a second to carbon capture, which is machines, or other processes that physically take the carbon out of the air that has been injected into it since the Industrial Revolution. You've been a pioneer in that area. First, can you tell me a little bit about your work and about how carbon capture fits in with this whole short-term, long-term combined strategy of addressing climate?
David Keith: The central most important thing to know about climate change is that climate change is proportionally cumulative emissions. That means that even when we have this day of global celebrations where net emissions are zero, you haven't made the problem go away. You've just stopped making it worse. That really is the most important thing to know, and so if you actually do want the distant future to be cooler, to have less climate change than the present, cutting emissions doesn't do that. Cutting emissions prevents it getting additionally warmer. But it doesn't make it cooler, you have to do it, but if you want to make it cooler, you have to either pull the greenhouse gas like carbon dioxide out, or you have to do solar geoengineering or some combination of the two.
I think carbon removal is riding a wave of visibility right now, and I think with some real moral hazard associated with it. It's sort of a technological shiny object a bit, which I think is being pursued partly because it seems to be easier than cutting emissions in some places. There may be some places where it legitimately is, to be clear. It may actually be cheaper to remove a ton of carbon than to squeeze the last 20, or 30% out of the economy, where it's very hard to do that. But in the short run, I think it looks easier because it's kind of out there, whereas the emissions cuts are changes in the economy we have to make right now. So I think that there's no doubt about a big, long-term utility to carbon removal. And I'm very proud of being involved in starting a company that's really made, I think, great strides for doing this in a practical way. I think there are lots of useful applications for this technology for sure, though, obviously, I'm kind of conflicted in saying that.
But I do think that right now there's a level of kind of over-visibility, where the reality is that the central thing ... I mean, less people mistake this, if I was czar and I was asked what fraction of the total flow of money, or political effort I would spend on these various things—you can argue about how much we should spend adaptation, but leaving adaptation aside—I would spend 96, 97% of the effort and money on cutting emissions. Now. I would certainly develop carbon removal technologies and develop them means in practice actually building some billion-dollar-class facilities and figuring out how they work and testing the claims of people like me, who've been involved in the technology development. The only way we really know what things cost us to build them. But that's still tiny compared to the kind of trillion-dollar-a-year flow of money we need to be cutting emissions now. And, in future, I think the world might very well want to do very large scale carbon removal to reduce the carbon burden. But my view is that probably happens mostly after emissions are down to at least half of the current level or a third.
Ralph Ranalli: How long is that process of removing carbon going to take in terms of the time horizon for it to really be practical and doing work at scale?
David Keith: Well, so how long it takes depends on how fast you remove it. I think the real insight is that carbon removal, a carbon removal machine, whether it's a big industrial machine, or something you've done to alter an ecosystem or something to add alkalinity to the ocean, all those things only provide a benefit as they work cumulatively over time. So, if you build a machine that removes a ton a year, there's all sorts of impacts of you building, you have to clear land to build it, you have to, there's a supply chain, and so on. The first year that it operates, it's only removed one ton. There's no real benefit, but over a hundred years, it's removed a hundred tons, so it's cumulative benefit.
So, what I think you learn from that is that carbon removal, if done in a rush to kind of try and keep the world at say under 1.5 degree C, I think it's likely to have side effects that might be really quite large compared to the benefits. I mean, I think that the scale of the supply chain, the scale of the impact of doing carbon removal very fast will be big compared to the benefits, because you don't get a chance to run these things long. My view is that assuming the world brings itself towards neutrality in say 2050, 2060, whatever, then you might want to use carbon removal over the next century or century and a half to gradually bring the world back towards ... I would vote for pre-industrial.
Ralph Ranalli: Now all of this assumes a lot of international cooperation and coordination. I mean we're talking about a coordinated strategy with potentially time horizons of a century or more. And everybody has to be on board, and the world’s nationals have to work together in numerous different areas. That level of coordination that it's going to take, is that unprecedented, do you think, in our history as human societies?
David Keith: So, I think that kind of overstates the level of coordination that's needed. I mean, the fundamental problem is cutting emissions. And with cutting emissions it is not necessary to have everybody on board perfectly, it's necessary to have the big economies that dominate emissions fundamentally agree all to accept costs of decarbonization in a way where there isn't egregious free riding. But that doesn't mean that you have to have some magic uniform set of rules or one carbon price to rule them all, which is not going to happen. And it doesn't mean that every country has to comply, I mean, emissions are a cumulative thing, if the big countries coordinate to drive emissions down, then you've had a huge benefit, and in principle that you could talk about carbon removal. If, there were some holdout countries that just wouldn't stop emitting and they were small, you could always just null it out if you like with carbon removal.
But I think, in practice that wouldn't be what happens in practice. There would be indirect force through trade and other agreements that would force countries to gradually decarbonize, partly because the world's energy system is all interconnected. So I think the coordination problem is hard, but it's not insuperable. It's important to say that on a country-by-country basis, we have crafted tough political deals inside lots of countries—China, U.S, Europe—to at great expense reduce conventional pollution. So in the U.S, the Clean Air Act has added more than a year and a half to the life of the average citizen now. And it did so at expenses that, at the peak, were a good percent, a good fraction of 1% of GDP. Really quite big numbers.
Now decarbonizing fast will be a few percent GDP, but a percent GDP is still leaves most of GDP to do it, do its thing. So, it is clearly possible to decarbonize in a way that we could afford. And I think the level of political attention to decarbonizing now is unprecedented. So I'm actually kind of optimistic that the world will actually move towards deep decarbonization. It won't do it as quickly as I would like, It won't do it as efficiently as we would like. There will be exploitation and so on. But I think you can have real progress in a world that's still very imperfect politically. I think the key message is that, I think in something that is not that different from the current international order, it is possible to have coordinated action to cut emissions. That is, I think the central news, we don't have to reinvent global government from the ground up in order to really cut emissions substantially.
Ralph Ranalli: I want to get to your most hopeful scenario in a minute, but what's the scenario that keeps you awake at night?
David Keith: I think, the scenario that keeps me awake at night most is that we have now this unprecedented wave of attention to climate, that there is some real action in most countries, but the real action is poorly designed and very cost ineffective, party because it's going to spend money on things that are kind of marquee ideas for cutting emissions, but may not actually be kind of that cost effective for cutting emissions. And, so we get a situation say five years from now where emissions really haven't gone down much, and prices for some commodities have risen, and you get a kind of populous revolt against the emission-cutting policies.
And I think, it's really important for people who want to see rapid action to cut emissions to think hard about how to stay a step ahead and avoid that, because this wave of attention is pretty special and it's inevitable, that some other global crisis will come up and climate won't be so close to the top agenda as it is now. And this window that we may have, of a few years where climate really is near the top of the political agenda, has to be used to implement policies that can stick, and policies that can really work to drive emissions down. And my fear is that will be squandered.
Ralph Ranalli: So on the flip side, what is your best case scenario?
David Keith: My best case is that this really is the turning point. That the greater attention to climate is happening at the same time as some technologies for de-carbonization really are more practical than they were before. So, I mean the extraordinary fall in the price of solar power is just stunning, and it enables all sorts of other steps toward decarbonization globally. And at the same time, I think in my rosy scenario, the willingness to do this as a multidimensional thing, to both cutting emissions seriously and also to begin to develop these technologies of carbon removal, which I think are necessary if you want to reduce the very long term weight of our emissions on the future; the willingness to get serious about adaptation, which if you take heat seriously means you might want to think about lots of local social things from getting people out of the top of buildings hot weather to air conditioning schools that really help reduce the burden of high temperature; and, I think taking geoengineering seriously but not as a Hail Mary pass, not as a binary thing, but as something that we do in addition to those other things to reduce some of the worst effects. And I think that, to me, the exciting thing is the one thing that I think technically we are the most confident solar geoengineering could do is reduce peak temperatures. And the evidence that peak temperatures really fall most harshly on the poorest means that there really is a chance that solar geoengineering could help to reduce inequality. Indeed, the only paper that's actually substantively looked at the impacts of solar geoengineering suggests it would reduce inter-country inequality pretty dramatically.
So I think, there really are opportunities to use the full suite of tools—in a way that wouldn't be perfect, there'd be I'm sure violence and disagreement and inefficiencies and exploitation—but I think it really is possible to imagine this is the turning point where the climate problem begins to be solved. And that people could begin to look towards a world where we actually go beyond just stopping making it worse, we go beyond being content that stopping emissions was enough, but really work to restore the natural world a little more, the way that we inherited it.
Ralph Ranalli: Well, this has been a fascinating conversation. I really appreciate your being here.
David Keith: Thank you. Thanks a lot for doing it. Thank you very much.
Ralph Ranalli: Thanks for listening. Please join us for our next episode, when we’ll talk to Harvard Kennedy School Professor Linda Bilmes, whose work is changing the conversation about cost and value in the context of political debates about everything from transportation to natural resources to social justice. If you have a comment or a suggestion about PolicyCast, please send us an email at PolicyCast @ hks dot Harvard dot edu.