Cooling the Planet Through Solar Reflection

Wednesday, May 11, 2022
The sun seen through smoke during the Hermits Peak and Calf Canyon fires near Ocate, New Mexico, U.S., May 11, 2022 REUTERS/Adria Malcolm

Senior Physical Scientist, RAND Corporation

Stewart M. Patrick

James H. Binger Senior Fellow in Global Governance and Director of the International Institutions and Global Governance Program, Council on Foreign Relations


Vice President for National Program and Outreach, Council on Foreign Relations

Stewart M. Patrick, the James H. Binger senior fellow in global governance and director of the International Institutions and Global Governance Program at CFR, and Robert J. Lempert, principal researcher and director of the Frederick S. Pardee Center for Longer Range Global Policy and the Future Human Condition at the RAND Corporation, discuss climate intervention techniques including solar geoengineering and considerations for policymakers in exploring new and uncertain climate change mitigation strategies


FASKIANOS: Thank you. Welcome to the Council on Foreign Relations State and Local Officials Webinar. I’m Irina Faskianos, vice president for the National Program and Outreach at CFR. We are delighted to have participants from forty U.S. states and territories with us today. Today’s discussion is on the record.

CFR is an independent and nonpartisan membership organization, think tank, publisher, and educational institution focusing on U.S. foreign policy. CFR is also the publisher of Foreign Affairs magazine. And CFR takes no institutional positions on matters of policy. Through our State and Officials Initiative, CFR serves as a resource on international issues affecting the priorities and agendas of state and local governments by providing analysis on a wide range of topics.

We are pleased to have Stewart Patrick and Robert Lempert with us today. We have shared their bios, so I’ll just give you a few highlights.

Stewart Patrick is the James Binger Senior Fellow in Global Governance and director of the International Institutions and Global Governance Program at CFR. Dr. Stewart previously served on the former Secretary of State Colin Powell’s policy planning staff for a range of global and transnational issues, including refugees and migration, international law enforcement, and global health affairs. He is the author, co-author, or editor of five books, including The Sovereignty Wars: Reconciling America with the World, and Weak Links: Fragile States, Global Threats, and International Security. And he also writes the CFR blog The Internationalist.

Robert Lempert is principal researcher at the RAND Corporation and director of the Frederick Pardee Center for Longer Range Global Policy and the Future Human Condition at RAND Corporation. Dr. Lempert is also a professor of policy analysis at the Pardee RAND Graduate School and author of the book Shaping the Next One Hundred Years: New Methods for Quantitative, Longer-Term Policy Analysis. He is also a member of California’s Climate-Safe Infrastructure Working Group, and has been a member of numerous study panels for the U.S. National Academies, including America’s Climate Choices and Informing Decisions in a Changing Climate.

So thank you both for being with us. Stewart, I thought we would begin with you. You just put forth a Council special report on reducing climate risk through sunlight reflection. We sent out that report in advance of this discussion, but if you could just give us an overview of the arguments you put forward and some of the policy recommendations.

PATRICK: Thanks so much, Irina, and I’m delighted to be with you all here and to share the virtual floor, as it were, with Rob Lempert, who’s done so much work on local approaches to climate mitigation and resilience.

I want to pay special tribute to Irina, who is by far the hardest-working employee at the Council on Foreign Relations with a massive portfolio and an evident need for a lot less sleep than the rest of us need to have.

This is my first time speaking to CFR’s State and Local program, and I look forward to your questions and comments about how you see this issue, where the rubber meets the road, which is of course in our communities.

I’ll get my thesis out front. You know, from the suffocating heat we’re seeing in India to these rampaging wildfires in New Mexico and other parts of the Southwest, the planet is sending us a pretty clear message, and that is the long-dreaded climate emergency is now. And so, faced with this clear and present danger, my report argues that the United States and other nations can’t afford to ignore the possibility of expanding their current strategies for managing climate risk to include sunlight reflection. This is also known as solar climate intervention or, perhaps more popularly, solar geoengineering. It’s been the subject of a lot of interesting science fiction, including Termination Shock and The Ministry for the Future just to name a couple that have come out. It basically would entail reflecting a tiny percentage of incoming sunlight back into space to limit the heating effect of solar radiation on our greenhouse gases while humanity goes about tackling these massive and protracted challenges of decarbonization.

Sunlight reflection, as you may know, has long been the third rail of U.S. climate politics, but that’s starting to change as the gravity of global warming becomes increasingly obvious. A year ago, the prestigious National Academies of Science advocated its enhanced study. And my report kind of takes things a little bit further, looking at the logic and feasibility of such intervention and what it would require for its effective international governance.

That we’re even having this conversation really is a testament to the dire straits we’re in. You know, at the big Paris Conference in 2015, as you recall, the U.S. and other governments unanimously said, hey, we’re going to keep the rise in average global temperatures well below 2 degrees Celsius and ideally no more than 1.5 degrees Celsius from pre-industrial times, and we’re poised to blow way past those targets. And the consequences, or at least potentially, could be quite devastating.

Yesterday, the World Meteorological Organization predicted that we actually have a 50/50 chance of hitting the 1.5-degree line within the next five years, which is decades ahead of what many had predicted just a few years ago. And this comes on the heels of a scary sixth round of assessments from the Intergovernmental Panel for Climate Change. So even if we—even if we hit the pledges that were made in Glasgow, the world is on track for warming of between 2.7 to 3 degrees Celsius this century, and that is—if you put it in Fahrenheit, it starts to seem like a lot. That is 4.9 degrees to 5.4 degrees Fahrenheit.

So the ramifications for human safety and well-being are going to be particularly dire, including in communities like yours and mine. We’re going to have more frequent, intense, and prolonged heat waves, droughts, wildfires, storms, flooding, and other calamities, and it’s already happening. The U.N. a couple weeks ago said that the frequency of what we misleadingly still call natural disasters has quadrupled since just the year 2000. And, as always, the poor will suffer the most. Even more alarming is this growing risk that the world is going to—that warming’s going to trigger abrupt tipping points in important parts of the Earth’s system, and that can include the rapid die-back of the Amazon rainforest or a shutdown of the Atlantic Ocean conveyor belt that keeps Europe temperate.

So it’s easy to be scared about this future of global warming, but my report says, you know, fortunately, there may be a lifeline, albeit in an unorthodox and imperfect way. And it would involve slightly increasing a reflection of sunlight from clouds and particles in the atmosphere to reduce climate warming. Society, I argue, needs to explore this option because climate change poses a major threat now.

Now, the world currently has three main strategies to manage climate risk, and I know that Rob will speak to at least a couple of them. One of them is emissions reduction, another is carbon removal, and a third is adaptation. Unfortunately, climate change is now outpacing all of these efforts. Emissions are supposed to decline by 50 percent over the next eight years to meet the 1.5 degrees target, but they’re on pace to rise by 16 percent. Direct-air capture of atmospheric carbon, whether by negative-emissions technologies or nature-based solutions like planting trees, is critical, but it could take decades for these innovations or land-use changes to go to scale. And then, finally, efforts to build resilience against warming and its impact, which no doubt you are all involved in, are essential but they’re also expensive, underfunded, and inherently limited because a lot of them will simply be overwhelmed by the interconnected climate system.

In short, I argue the world confronts a high-stakes timing predicament. We know we have to do more, we know what we have to do, but we’re not doing it fast enough to prevent soaring temperatures. How much worse things get depend on how hot it gets. Given this dilemma, I argue the world can’t afford to ignore a potentially rapid climate response that could, as they say, shave the peak of global warming, keeping people safe and natural systems stable while we make the long transition to net zero.

Increasing sunlight reflection to cool the climate could be accomplished in various ways. The two most promising options are based on things that already occur.

One approach would be to involve dispersing aerosols in the upper atmosphere or stratosphere, likely from aircraft, and this would be a safer version of the cooling effect of particles emitted by volcanic eruptions. You may recall Mount Pinatubo, which erupted in 1991. It reduced global temperatures by some estimates by half a degree to 1.1 degree Celsius over the ensuing fifteen months.

Another approach would involve spraying sea salt mist from ships or ocean platforms to brighten low-lying marine clouds in what’s called the troposphere, and this would be a cleaner version of the global cooling effect that we now see from atmospheric pollution. In fact, the pollution that we have already put into the atmosphere is estimated to keep temperatures about half a degree to 1.2 degrees Celsius than they would be otherwise, and so that’s going on right now. And models suggest that this could be remarkably cost-effective. It might be done for as little as $10 billion a year, which is a tiny fraction of the estimated 275 trillion (dollars) it’s going to cost to decarbonize the global economy by 2050.

So I’ll just finish up with a few remarks here. Despite its promise and precedence, the idea of sunlight reflection has been controversial, though that’s starting to change as the risks of warming intensify. There’s a lot of queasiness about playing with Earth’s thermostat. There’s worry that there are uncertain risks, and it’s true there could be unintended consequences which we need to take seriously. There’s also fear of what economists call a moral hazard; that is, that the mere prospect of this will give governments, corporations, and citizens a perceived hall pass to continue their polluting ways.

I argue that these concerns really do deserve careful consideration and scrutiny. This is an untried enterprise with a risk of unintended consequences and human error. But these risks need to be assessed not alone as if we inhabited some sort of a perfect world, but alongside the known dangers, tensions, and inequities of an ongoing if unwitting experiment we’re already performing by pumping greenhouse gases in the atmosphere. The key question to ask is: Can increasing the reflection of sunlight in the atmosphere reduce the dangers posed by global warming?

Unfortunately, we don’t know because we don’t have the scientific certainty about the potential efficacy and repercussions of this, and we don’t have any monitoring systems or multilateral rules of the road to govern such intentional manipulation of Earth’s climate system. And I argue that this dual vacuum is untenable because it leaves policymakers flying blind, unsure of the feasibility of this option, and unable to make informed, responsible choices. It also increases the danger—the lack of international rules in particular—of something that the National Intelligence Council has warned about, the danger that a single power could someday take matters into its own hands, launching freelance interventions with destabilizing geopolitical and economic impacts.

So I basically say we have to close two gaps.

To close the first knowledge gap, I recommend that the Biden administration and Congress collaborate to launch an ambitious, well-funded, transparent, and accountable research program on sunlight reflection science grounded in international cooperation. And it would build on the recommendations that were made by the National Academies, but with a lot more money.

To close the second gap, I call on the United States—that’s the governance gap—I call on the U.S. and other governments to begin negotiations on a multilateral framework needed to jointly assess the feasibility, consequences, and wisdom of actually doing this, because we could decide this is a terrible idea. And also, though, importantly, to take collective decisions about any future deployment. And I argue that although, obviously, we live in a pretty complicated negotiating landscape right now, I believe that the mutual vulnerability to climate change could create some opportunities for strange bedfellows, including between the United States and China and between the United States and developing ones.

As the report repeatedly emphasizes, sunlight reflection’s not a solution to climate change since it doesn’t effect emissions or eliminate atmospheric carbons. It’s more like methadone for a world weaning itself off of fossil-fuel addiction. But it’s something that we can’t afford to at least explore. You know, we have to consider all of our options, and I think it would be irresponsible not to evaluate its viability and possible consequences and at least give it—give it the science and consideration that it’s due before we dismiss it out of hand.

So those are my opening remarks. Thanks.

FASKIANOS: Great. Thank you, Stewart.

Let’s go to you, Rob, to talk about the policy implications for these kinds of climate interventions and what you think officials in states and cities should be thinking about in terms of mitigating the consequences of climate change.

LEMPERT: Great. Thank you, Irina. Thanks for the introductions, and thanks for setting this up, and, as Stewart said, all that you do to—(laughs)—make these programs run. And welcome, everybody.

Yeah, so this is actually a fascinating topic to engage with state and local officials on. I mean, no one is suggesting that you put sunlight reflection into your climate action plans. But there are a number of places where I think this is an important topic that does connect with what’s going on at state and local levels.

I mean, so the first is that this whole consideration of sunlight reflection is really a reason to accelerate your efforts at mitigation, reducing greenhouse gases, and adaptation, you know, achieving resilience to extreme weather and climate events. You know, the only reason, as Stewart so eloquently laid out, that this is on the agenda at all is because of the challenges we face are so imminent and significant.

And sunlight reflection is, at best—I mean, it can’t be a permanent solution. At best, it’s a way to shave the peak, to keep temperatures low while we make a transition to a low-carbon emitting economy. And it might also be something that we would need to turn to in some sort of emergency if one of these feedbacks—low probability, but high consequence—feedbacks actually manifests itself. You know, climate is very much a risk management challenge. And, you know, one fundamental risk management strategy or principle of risk management is to have a diverse portfolio. And so essentially, you know, what we’re doing with sunlight reflection is making our portfolio more diverse. And so we shouldn’t make it less diverse as we consider this option.

A second point is that while sunlight reflection—deployment of any sunlight reflection system is definitely in the future, there are other types of climate modification which are, you know, currently on the table and currently happening. In particular, this idea of carbon dioxide removal, extracting carbon dioxide from the atmosphere. Which can create opportunities and risks at the local level, which might be something that you all might want to consider. So Stewart mentioned nature-based solutions—reforestation, managing agricultural and other natural lands in ways so that they store more carbon. And there’s a whole issue of biofuels, and the issue of direct air capture, machines that actually suck carbon out of the air.

And there are examples of—and firms and technology demonstrations, market demonstrations of all of these going on around the country and around the world. And so you may, in your community—they all pose opportunities and risks. You know, for instance, direct air capture are machines which suck carbon out of the air, or biofuels. You can, in California, where I live, take dead trees and build little mini refineries and turn those into fuels, and create then carbon that you can sequester underground. And all of those create economic opportunities, but they also create various sorts of risks—risks to ecosystems, risks from storing carbon underground, which you may want to engage with how should you exploit those opportunities, manage those risks?

And then the place where you may engage directly with the sunlight reflection is that—well, is the—is the notion—or, the potential for outdoor experimentation with this technology. And to date, for sunlight reflection, particularly the stratospheric—putting particles in the stratosphere to help increase the reflectivity of the Earth to reflect sunlight—has all been in effort. In laboratories and computer modeling the science may be getting to the stage where outdoor experiments may be appropriate. By and large, at this stage they’re all going to involved negligible environmental consequences. You’re releasing, you know, only a few pounds of material into the atmosphere, which will really have no environmental—noticeable environmental impact.

And so it’s straightforward for these experiments to satisfy existing environmental impact laws. But many in your community, many worldwide may see such experiments as symbolically important. So there—some communities may face the question about, you know, is it appropriate to have such experiments in their locale or not? And so my own view tends to be to see this as an opportunity for public engagement, and public engagement and participation is important. You know, first experimenters may face backlash if essentially they don’t want to ask permission to conduct an experiment in people’s backyards. Backlash would be entirely avoidable.

And second, and sort of the large point, is that across the board, to address the climate change, we’re going to need to build massive amounts of new infrastructure—from solar and wind machines, to power lines, to renovated buildings and so forth, different sorts of streets. Actually, there’s a question about reflecting roofs. And in order to manage climate risk, we’re going to need to build fast and build fair in equitable ways. And I think public participation is going to be an important part of that, and we need to do that better than we’ve been doing that in many places. And sunlight reflection experiments I think provide us with an interesting and unique opportunity to advance methods for getting the public engaged in these significant, serious, but really important risk management questions.

FASKIANOS: Great. Thank you so much. So we’re going to go to questions. There are already several typed up in the chat. So if you would like to ask a question you can either write it out or you can also click on the raise hand icon and we will call upon you. You can accept the unmute prompt and state your name and affiliation and your state, just to give us context. And, again, this is a great forum to share with us what you’re doing in your community. So we encourage you to do all of that.

So I’m going to take the first just—there are several in the chat—from Liz Ellis, who’s a city councilperson in Aberdeen, Washington. I think you touched on this, Rob. Should the national building code require all roofs to be painted/made with reflective material?

LEMPERT: Do you want me to jump in, or?

FASKIANOS: Yeah. I think that one should go to you, mmm hmm.

LEMPERT: Yeah. Yeah. I catch a little bit on the word “all.” So I’m not sure whether all roofs need to be, but I think the basic point you’re asking is an emphatic “yes.” We need to revise our building codes to take into account changing climate. There’s been some fascinating studies which look forward and look at how many places in the country building codes are based on climate data from the 1960s and ’70s. You know, support from decades ago. And the climate today is already significantly different than the climate those building codes envision and is changing fast.

So the basic point is, yeah, we need to revise our building codes to be forward-looking, and so that we’re building for the climate that’s coming and not the one that we’ve had, or the one even that we’re living through today. And that will include, in many places, reflecting roofs and reflecting streets, you know, particularly in the southwest U.S., where I live. That sort of thing is going to definitely be important.

FASKIANOS: Great. Thank you. So we have a written question from Jeffrey Sayegh, who is an aid for New York Assemblyman Thomas Abinanti.

This is directed to you, Stewart. You mentioned using airplanes and ships to disperse cooling agents. You stated it could cost 10 billion (dollars) a year. Can you elaborate on this price and how this price tag came about, this number? As far as I’m concerned, we are the ones setting the price. For all we know the cost could be a lot lower if it benefits everybody.

PATRICK: Yeah. That’s a great question. Yes, I mean, conceivably. I mean, that’s the price tag for—I mean, the estimated price tag by Alan Robock and a number of other climate scientists who basically suggest that for under $10 billion it would be the cost for flying several dozen planes relatively continuously in the stratosphere over the course of about a year or so. And that would also include the materials that would be used to be dispersed. It could be sulfates. It could be calcites. There are a number of different materials that people have talked about. But certainly, that expenditure could be shared in a multilateral framework, which is something that I would definitely endorse.

And the report goes into some detail about the importance of making this a multilateral partnership, rather than simply a sort of a unilateral U.S. effort. Partly to, you know, put the emphasis on international cooperation as opposed to something that, in a sense, is being unilaterally placed on—or, imposed on other countries. That’s why it makes—the report makes a major emphasis on the importance of reaching out, particularly to developing countries, to avoid some sort of neocolonial notion. This is if you were to do this after all the science is done, as you don’t have any neocolonial and sort of imperialist lens on this. What you want to do is basically talk to—understand the needs of developing countries which, frankly speaking, are the ones that are taking climate change hardest on the chin.

FASKIANOS: Great. So just as a point of clarification from Erica Norton, who’s a city council member in Federal Way, Washington, just can you go through the tradeoffs? Reflect and stop the sunlight, but at the same time changing our energy source to solar. So how do you sequence those two things and bring them into—you know, so they’re not seemingly at odds?

PATRICK: You’re saying we need to reflect at the same time—yeah. I mean, I—OK, right, yeah. No, there is a question—no I understand that. There—I mean, one of the objections to sunlight reflection is that wouldn’t it hurt, in a sense, solar power, of all the renewables, the most? There are a number of scientists that have looked at this and studied and suggested, you know, there would be a slight—there could be a slight reduction in the amount of solar power that you generated, but the overwhelming impact would be to reduce average global temperatures. And that it wouldn’t be a huge hit on solar power. So the tradeoff, as far as the scientists who have looked at it suggest, is that it would definitely be worth it. And that it wouldn’t put solar power out of business, because we’re only talking really about reflecting perhaps 1 percent of incoming solar radiation. It’s hard to imagine that that would make solar power—change the economics of solar power.

FASKIANOS: Rob, do you want to comment on that as well?

LEMPERT: Yeah, nothing on that.

FASKIANOS: OK. So we’ll take the next question—and people should raise their hands too, because I don’t love reading all the questions. We want to hear from you. But I will.

Jackson Kaspari, who is a resiliency coordinator in Dover, New Hampshire, about where I was born. (Laughs.) The largest uncertainty for impacts on global radiative forcing come from aerosol and the aerosol interactions with clouds. With incredibly complex atmospheric chemistry at play and the potential for long-range transborder regional implications, how could this be employed in a controlled fashion? He did not tackle it in his Ph.D. seminar because of the controversy. So could you see remote sensing and drones playing a large role for monitoring atmospheric—

PATRICK: Again, this is—yeah, I mean, this is precisely—I mean, you know, Jackson makes a fantastic point. I mean, this is precisely—it is unbelievably complex. And, you know, DOE has some of the most powerful supercomputer capability in the world. And yet, you know, DOE does not have the mandate or resources to do sort of direct monitoring of cloud-aerosol interactions in the troposphere, the lower part of the atmosphere. And so, you know, that’s one of the reasons why this calls for a significant budget. Now, it’s still peanuts compared to something like the defense budget, but it does envision a research program starting at $300 million a year and going up to about half a billion dollars a year by year five.

But it also calls for increased investments in NASA satellite capabilities. It calls for increased investments in what’s called the Earth’s Radiation Budget Program at NOAA, which in particular is looking at sunlight and its interaction with particles in the stratosphere. And so this would have an entire suite of Earth observation systems ultimately attached to it so that we could get to some of the granularity, as they say in the military—(laughs)—of—and the details of, you know, what the dynamics would be. Because Jackson’s absolutely right. These are enormously complex systems. We are also discovering how much we are disrupting those complex systems with our current greenhouse gas policies.

FASKIANOS: Rob, do you want to also add to that?

LEMPERT: Yeah. Why don’t I do that, and then I can link it to the question about the small experiment that was proposed for Sweden. Yeah. As Stewart suggests—I mean, and the question suggests, I mean, the chemistry and the dynamics of the stratosphere that layer the atmosphere above the one we live in, where these particles would go, is tremendously complicated. And at some point to understand the potential and whether this technology would work or not, and how best to do it—you know, whether we would need drones to track things, et cetera—suggests we need to start—would need to start doing outdoor experiments.

And the small experiment that David Keith proposed for Sweden would send a balloon up, release about two or three pounds of material—calcium carbonate—into the stratosphere. And then have little propellers and fly the balloon back through the plume to measure what was going on, and essentially see if the models that the atmospheric chemists have for predicting where that plume would go and what its properties would be, would be, in fact, what we would observe. It’s a tiny, small step towards answering the sort of question that was asked.

And that experiment did not take place. And—at least my interpretation, since I had some involvement in that process—was that the experiment, the location of it—the north of Sweden has a spaceport up in the northern part of the country—that it was chosen and announced that the experiment was intended to be there on—entirely on scientific grounds, without any consideration of the people who live there, or even any discussions with the people who live there. So I think the main takeaway from that for me is that any experimental location needs to get on the list with both scientific and—considerations, and considerations of who lives there. And that no experiment ought to be, you know, announced or planned before people in potential launch sites are engaged on what they think about it, and have a chance to weigh in.

PATRICK: Yeah, I agree that laying the groundwork with the communities is essential. In this case it was particularly perhaps sensitive because it was in the location of the inhabitants where all the Sami people who have often been marginalized, even in as otherwise nice Swedish political system. So I think that that, plus some environmental concerns—often exaggerated, I think, environmental and health concerns, given that, as Rob said, this small quantity that was going to be there. But I think it had some symbolic importance. And I think that that is a lesson that was learned from that experience.

FASKIANOS: Great. Just I will answer one of the questions. We will be sending out after this event a link to the video and transcript so that you can obviously have a copy and share it, as well as a link to Stewart’s report. So we’re going to take the next question from Amy Cruver, who is council member from Tacoma, Washington. Actually, Pierce County Council.

How much carbon dioxide is required for healthy plant production? And is the goal now to remove epigenic greenhouse gases as well as naturally occurring ones? I don’t know who wants to take that.

PATRICK: Yeah, an interesting question. Yeah, I am not a—you know, I am not a botanist, or I’m not sure that I have—or a forester. So I’m not sure that I know, you know, the precise level that would be healthy. Undoubtably different species would respond differently. But the idea here is—you know, there’s no—in the global sense there’s no distinction between sort of what’s naturally occurring carbon dioxide once it gets into the atmosphere and ones that are sort of anthropogenic in nature. The idea here would not be to try to—I mean, at most it would be trying to offset the level of carbon dioxide that has been put in the atmosphere over the last two hundred years or so, since the start of the industrial revolution. And that is quite a herculean task.

Actually, just removing it—just thinking of carbon dioxide removal—if you were going to try to remove—there’s one calculation we had, a report from actually a scientist who works at the University of Washington, speaking of Tacoma, your neighbors. They calculated that the amount of carbon that you’d have to remove from the atmosphere to get down to sort of preindustrial times, if it were—if it were transformed into solid black carbon, it would be the volume of Mount Rainier, basically thirty cubic miles of solid black carbon. So this is a huge enterprise that we are involved in. So that is the kind of carbon that this would have to offset.

Again, decisionmakers—political decisionmakers, leaders, could decide whether or not they just want to stop the heat at 1.5 degrees Celsius. But in principle, you could reduce that heat back to preindustrial levels. But again, you have to keep on doing this until you decarbonize the global economy and reduce emissions already there, because there is—that’s why the book that I mentioned, called Termination Shock, if you were suddenly to stop doing this, you run into problems because the—suddenly you have without—if you haven’t reduced the quantity of greenhouse gases in the atmosphere. Because if you suddenly stop doing this intervention, then you risk having a very strong spike in temperature. And you have that spike happen much less gradually that it would have occurred otherwise. So it is something you need to keep doing. That’s why this can only be a supplementary intervention, alongside carbon dioxide removal and emissions reduction.

FASKIANOS: Rob, do you know the exact figures? Yeah.

LEMPERT: Yeah. Yeah, well, let me weigh in on two points here. One is, you know, what is the perfect level of carbon dioxide in the atmosphere? And, I mean, that’s a hard question to answer. Some plants are going to do better with higher. Some are going to do better with lower. Generally, all these targets and goals are based around the idea of trying to stay close or return to something at the level of what we had before we began the industrial revolution and, in particular, the huge and very beneficial explosion of economic growth after the Second World War.

There was a question I think earlier on about, well, carbon dioxide has changed levels, and temperature levels have changed, you know, over the Earth’s history. Why is it such a big deal? I mean, the—and this goes to the plant question issue—if you look back at all those wonderful, you know, pictures of dinosaurs that, you know, you and your kids have looked at, I mean, there are plants but they’re very different from the ones we had now.

So the Earth has existed in different states than the one we have now, but the transition between them have often been pretty abrupt. We’ve had several mass extinctions in the history of the Earth, many of them associated with big temperature changes and big changes in carbon dioxide. And those things actually happened at a much slower pace than we’re currently changing the landmass—or, the atmosphere. And, you know, had significant disruptions. Things we would not want to live through. So basically, you know, trying to keep the atmosphere roughly the composition it was before we started these large-scale changes to it are—is the goal.

On this, you know, scale of Mount Rainer point, I mean, that’s one way to look at it, which suggests how big it is. But another way to look at it is to make a significant dent in the current CO2 levels and bring them back down towards what they were before the industrial revolution, it also would take roughly the same amount of carbon removal technology and sucking through air at roughly the same magnitude of all the car radiators of all the cars we’ve put on Earth. So it’s a massive endeavor, but not different than the massive endeavor that we’re already engaged in to change the Earth’s atmosphere for beneficial purposes. So humankind is already changing the atmosphere at a massive scale. And what we’re talking about here is trying to engineer that intervention to be less disruptive to the climate.

PATRICK: Yeah. Can I also just say, there was a question in the comment box which was basically saying, look, during the last, you know, ten thousand years there’s been a lot of—there’s been some significant swings in temperature. You know, if you look, though, at the period of the Holocene, which is the current geologic era we’re in, although some people say we’re now in the Anthropocene. But over the last twelve thousand years, you really don’t see a prolonged variation over basically 1 degree Celsius or 1 degree—minus-1 degree Celsius from where we have been. And then you start to see this tremendous spike over the last—the last two hundred years, particularly over the last fifty years or so.

And the other thing is that the buildup of carbon dioxide in the atmosphere is quite remarkable. I mean, excuse me, but not just in the atmosphere, but also in the oceans. The oceans are now 30 percent more acidic than they were two hundred years ago. And that is having a devasting impact on aquatic life and marine food chains. Now, obviously, sunlight reflection doesn’t do anything about that, which is another reason why it can only be a complementary strategy, because it doesn’t solve that problem.

FASKIANOS: Suds Jain had written a question, which was answered, but he also indicates that he works with the University of Washington on the MSB (sic; MCB) project. So I’m just—is that the same project that you’re referencing, Stewart?

PATRICK: Yeah, MCB, marine cloud brightening. Yeah, it’s a really—I am familiar. I know there’s a number of people who work there. But I’m familiar with Sarah Doherty, who was on our advisory board. We had a tremendous advisory committee. But she and her colleagues are investigating this question of marine cloud brightening and actually experimenting with—you know, even developing prototypes of nozzles that you would use to sort of loft sea salt particles, just sort of benign sea salt particles, into the troposphere, but only even a few hundred feet. And then, you know, boundary layer convection will take the up and into the clouds. And they’re—I believe they’re planning—or, the idea is that sometime in either late this year or in 2023 there would be some at least trials over the ocean. There have already been some trials, I believe, off the Great Barrier Reef to try to use—to try to create local cooling. Because, of course, as you know, coral bleaching is a huge problem on the GBR.

FASKIANOS: Great. So, Suds, if you want to raise your hand to elaborate on your project, that would be fine.

I also want to just point out, from Jeffery Sayegh in New York state, we give tax rebates to homes to implement solar energy. The problem with these rebates is that they do not cover the cost of a battery, so when there’s a blackout solar’s not any use if you don’t have a battery. There’s currently zero federal assistance towards battery powered solar homes. The average family cannot afford this, and most refuse to switch over from natural gas to solar power. So that’s just a comment there.

I want to go next to Brian Beck, council member in Denton, Texas. Just stating that the atmospheric reflectivity are global community efforts. What is the role of municipalities in this sort of response? So connecting it to what people should be thinking about in their communities. Rob, I’m going to throw that one to you.

LEMPERT: Yeah. Yeah. So I think, you know, proceeding with your climate action plans, that include adaptation and mitigation, you might consider including some type of carbon removal. You know, in particular based on nature-based solutions, but perhaps becoming engaged with some of the demonstration projects with carbon capture and storage, particularly if you have geological formations where carbon storage might be—might be an option. And the—and then the connection with the sunlight reflection is a little bit less—you know, less direct. But you may want to consider, you know, your state’s view on what—on experimentation. If there are—if there were interest in open-air experiments in your state or city, what would be the conditions under which that would take place? What sort of public participation, what sort of other conditions would you like to see for that to take place?

FASKIANOS: Mmm hmm. OK. I’m going to go next to George Tyler, trustee in Essex Town, Vermont. Do the proposed sunlight reduction strategies reduce all wavelengths and frequencies of incurring—I’m sorry—of incoming UV radiation across the board? Or are certain wavelengths and frequencies affected more than others? Stewart, is that a question for you? I think—is Stewart frozen? I think Stewart’s frozen. He’s frozen! (Laughs.) OK. So, Rob—

PATRICK: Can you hear me?

FASKIANOS: Yes, Stewart. Go ahead. No, I think you’re going to have to take it.

PATRICK: How about this?


FASKIANOS: Wow, you cloned yourself. We have the fixed Stewart and the—on a different device Stewart. (Laughs.)

PATRICK: What’s the question?

FASKIANOS: So the question was—let me just pull it back up because I marked it as—oh. Do the proposed sunlight reduction strategies reduce all wavelengths and frequencies of incoming UV radiation across the board? Or are certain wavelengths and frequencies affected more than others?

PATRICK: I believe that they’re reduced across the board, but I would need to check on that. Do you—


LEMPERT: Yeah. My answer is the same, yeah. I mean, I—most particles, you know, have absorption spectrums and, you know, work differentially across different frequencies. But I don’t—I actually don’t know how flat or how—you know, I don’t know the answer to that question. It’s actually pretty googleable. Let me try to check while we’re talking.

FASKIANOS: OK. Erica Norton from Federal Way, Washington has a couple of questions about—and I know you addressed her—the first question, Stewart. But we are at a solar minimum and in the coolest recorded warm period in 10,000 years. What effect will reducing the sunlight have on farming and food production? And the corollary to that, since trees and foliage derive their sustenance from carbon and sunlight, what will happen to the trees and foliage if they do not have carbon and sunlight with which to feed?

PATRICK: Yeah. Again, a number of climate scientists have looked at both of those questions. And there just—in terms of food production, that does not seem to be a—does not seem to have a huge impact. The impact—the potential impact there, and this is the caveat, is that there could be regional differences in precipitation patterns. This sunlight itself—the reduction in sunlight itself could, at the very margin, have some—you know, some impact—(audio break)—productivity.

But it’s more the question of—because if you do this, you’re not returning the climate to its preindustrial situation. You’re basically reducing the heat in the atmosphere, but what are the ramifications of that for precipitation in different areas? And so it’s possible—and this is what we have to find out with more science. It’s possible that there will be winners and losers in this, at least—at least modest winners and losers. And there are a few more worrisome potentialities, although it’s controversial. One of them is that sunlight reflection could have perturbations on the Indian Ocean monsoons.

And if that were the case, there could be rather dramatic consequences for Indian agriculture. It’s been something that Indian scientists have talked about and have suggested we need more research for it. But I don’t—at least what I’ve seen does not—it is not huge ramifications for agricultural productivity.

LEMPERT: As a simple rule of thumb, climate change is about water. Because water carries most of the energy in the atmosphere. And so a small change in carbon dioxide, its biggest effects on agriculture, as Stewart was saying, is where the water goes. So, you know, whether you’re going to have more or less precipitation, what season it comes in, whether you have floods, whether you have drought, and the effects of—the effects of carbon dioxide in the atmosphere, the effects of change in the reflectivity of the Earth, the big effects on agriculture are, by and large, going to be where the water goes. And that’s the thing that we don’t understand very well.

FASKIANOS: Great. Going to Tony Rogers, who’s an attorney in La Paz County, Arizona.

Are the so-called chemtrails that we’ve been seeing in the sky over the past several years really solar reflection experiments already underway?

LEMPERT: Yeah, I can answer that. No. There is a lot of—there have been a lot of very sort of rich—there’s a rich tradition of looking at chemtrails as some sort of experiment either being undertaken by the government or by some malevolent actors or, conceivably, even, you know, by some international authority like the United Nations. The chemtrails—at least the so-called chemtrails, as I understand them, are basically, you know, similarly vapor trails that are left behind by aircraft. There may be other sort of naturally occurring phenomenon, like cirrus clouds, et cetera, that make something look like it’s been a trail left behind.

But the question does raise an interesting point, which is how do we know if somebody’s actually started doing this? And from what I understand, the—particularly in the wake of the National Intelligence Council’s report last fall that some countries could start to do this—there’s been a certain amount of increased attention, shall we say, at different parts of the U.S. government about how one could actually monitor whether or not this was going on, and could we actually tell if there was a clandestine program, say, I don’t know, not to pick on United Arab Emirates or India or China or some other country. But how would we know whether or not they’d actually launched something?

And there’s—I think the answers are mixed as to whether or not we could, through our current observational apparatus—be able to ascertain that question. And you could imagine that this sort of issue and the controversy surrounding it could really disrupt international politics. You could even imagine some countries threatening to do this as a form of blackmail, either to get other countries to give them aid or to, you know, enhance their own emissions efforts—emissions reductions efforts.

FASKIANOS: There’s one more question before we wrap up, if anybody wants to raise their hand or write in another question. But how can we go about and start implementing this technology and installing them on ships, cruise ships, airplanes, et cetera?

PATRICK: That’s really interesting. I mean, there are—there are proposals right now to put—it’s less to spread—(audio break)—or other material in the stratosphere, but more to sort of put monitoring equipment and analysis equipment on some airliners, or freight airlines, that you could actually—while the plane was up there, they could actually be measuring the state of the stratosphere, which would seem to kind of make sense, right, with the atmosphere.

With respect to, you know, the—I think that any—at least the planes for deployment of this sort of thing, if you didn’t do it by balloons, which is one possibility. Another way you could even use sort of the equivalent of artillery shells, in a sense, to sort of place some of this material up in the—up in the atmosphere. But the planes would be sort of specially modified, relatively higher altitude airplanes, to go about this. Yeah. And it’s—you know, the same—the same thing has been suggested for cruise ships and other sort of oceangoing vessels, which presumably could serve also as platforms for actually deploying some of this. Already, as I mentioned, you know, pollution creates a certain amount of brightness in clouds. And that includes low-lying marine clouds.

We’ve talked about chemtrails before, but—which, you know, the vapor trails basically from airlines. You get a similar thing if you look at, from down at the ocean front, satellites. You can see so-called ship tracks. And that’s basically ship pollution that has gone up into the air. And it actually brightens marine clouds. And so those things are already going on. But you could imagine trying to piggyback on some of the existing sort of merchant fleets that we have around the world, to try to do this. I haven’t seen much written about that, but they have talked about platforms and ships as being a place that—a way that you could actually do this.

FASKIANOS: Great. So I’m going to take the final question from Renee Suwaneski, who’s from Bartlett Village, Illinois.

And if you could, you know, react to her question and also any parting thoughts, because we are coming to the end of our time. So we’ll first go to you Stewart, and then to Rob. So, Stewart, you mentioned winners and losers when answering the question of food shortages. How would those winners and losers be determined? And, you know, if you could tack onto that any closing thoughts you would like to leave us with.

PATRICK: Yeah. No, I mean, it’s a huge issue because, you know, one could imagine losers—and this would be quite politically—geopolitically sensitive. You can imagine losers being Russia, right? It’s been interesting, we tend to think of the geopolitical rivalry between the United States and its Western partners on the one hand and increasing and maybe even a Cold War against the sort of two big authoritarian players.

But what’s interesting with respect to climate change is that, you know, the Chinese are very worried about water security. And so they would conceivably be winners if they had a little bit less heat to worry about. Whereas, in Russia there’s been much less—they’re kind of much more easy come easy go when it comes to climate change because, you know, their wheat belt is moving north in Siberia at quite a clip. And so they may see this—and, you know, obviously the northern sea route between Europe and Asia. So they may see this as a way to be winners. You know, determining all of these things is really going to have to depend on an incredible, much more detailed, sort of map of vulnerabilities and benefits. And that probably would have—there would have to be some international regime eventually to have some level of compensation.

The last point I’ll just make with respect to just a general point, which is that I do want to reiterate that this is not a solution to climate change. I also want to reiterate that I’m not advocating for its deployment, just its—at this stage—just its study. Whatever happens, it’s very important that we think about how these different—these four arrows in our so-called quiver of managing climate risk, actually relate to one another and actually complement and reinforce one another, rather than having one being seen as the silver bullet. Because, as Rob mentioned, one of the priorities with respect to managing your portfolio, stock or otherwise, is to diversify.

FASKIANOS: Rob, over to you.

LEMPERT: Yeah. No, very interesting question. And I think you have to separate into can we—how well can we predict who the winners and losers might be, and then how, well, if we ever did this sunlight reflection and it, in fact, created winners and losers, could we tell? And so on that second question, the science of what’s called attribution, being able to attribute particular storms, droughts, or heat waves to the effects of climate change has gotten much, much better in the last couple of years, which I think will have a lot of implications across the board.

But in this particular one, we probably would be able to tell—you know, have a pretty good ability to tell if there was a major climate intervention and there was, say, a big drought or a lack of monsoon in a particular place. We’d probably be able to do a pretty good job of attributing it to an action that some country or, you know, entity had taken. And then, as Stewart said, that that would work a lot better if there were ways to think about compensation beforehand, as opposed to after the fact. Predicting what the effects of a climate intervention might be is—you know, we’re a long, long way from that. And part of the research agenda that, you know, Stewart’s outlined would be to improve our ability to do that.

And, yeah, as parting thoughts, just to thank everybody for their interest and just to, again, reiterate that, you know, addressing climate change, there is no silver bullet and it’s really something where we need to work across the board on a diverse portfolio of solutions, and ones that are, you know, customized for each particular location and state and locality. And, yeah. Thanks, all.

FASKIANOS: So I’m going—I’m going to ask one last question from Amy Cruver, because I think it is important. What effect does the war in Ukraine—is it having on our efforts to go carbon neutral or net zero? Like, in terms of how much is this going to set us back, the war and what’s happening there? Not fair to end on this, but I just thought if you could give a quick prediction.

PATRICK: Yeah, I just—I think it’s set it back quite significantly, at least in the medium-term—short and medium-term, because it’s put an emphasis on, you know, energy security. And I think that there’s a long-term way of thinking about energy security, which is going really more towards the renewables. But I think that at least in the short term it’s definitely put the emphasis on, you know, fossil fuel extraction. And even removal of things like gas taxes and things like that at the pump. But Rob may have other views.

LEMPERT: Yeah, no, no, I agree with that. I mean, it also has highlighted the—some of the dangers of dependence on fossil fuels. And so I would just offer that, you know, as sort of a general guideline, perhaps the best way to respond to this crisis is trying to, you know, enhance use and production of current fossil fuel assets, but direct investments—any new investments towards other types of energy might, in the long term, be a productive way to respond to the crisis.

FASKIANOS: There’s a theme here. Diversity. (Laughs.) Diversify and try to put—use as many tools as possible at our disposal to come into play.

Well, thank you both. This was really, really great. We really appreciate your being with us, to you, Stewart, for authoring this report. Again, you all should, if you haven’t already, take a look at it. We will send out a link to the recording and transcript. You can follow Stewart Patrick on Twitter at @stewartpatrick and Rob Lempert at @robertlempert. So go there. You can also sign up for Stewart’s blog on CFR.org, The Internationalist. So I encourage you to do that. And as always, visit CFR.org, ForeignAffairs.com, and ThinkGlobalHealth.org for more expertise and analysis on these issues, and more. And do email us, [email protected], to let us know how we can support the work that you are doing in your communities. We appreciate all your efforts.

Hope you all stay safe and well. And we look forward to having you join us for the next webinar. So take care.

LEMPERT: Thanks, all.

PATRICK: Thanks.


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