Climate Justice: An Issue of Morality, Legality and Egality
Q&A with Cass Sunstein
Credit: Rose Lincoln
Following the publication of Climate Justice, What Rich Nations Owe the World – and the Future (The MIT Press, February 2025), Keith Forman, ALI Fellow 2020, sat down with author Cass Sunstein to discuss the book and motivations behind its creation. Cass Sunstein is currently the Robert Walmsley University Professor at Harvard. He is the founder and director of the Program on Behavioral Economics and Public Policy at Harvard Law School.
Keith Forman: Cass, one thing I've always admired about you is your interdisciplinary approach to tackling the world’s problems. You have a background in law, economics, social science, and behavioral science, you’re a walking interdisciplinary interdisciplinarian. How did you come to author a book on the topic of climate justice?
Cass Sunstein: Thank you for the kind words. I've been working on the topic of climate justice since approximately 2004. I was but one of the people on a very large train, because the international negotiations about climate involve contests between wealthy countries, saying, “Let's do something”, and poorer countries saying, “Yes, let's do something, and please help us pay for it”. The question was one of corrective justice and distributive justice, and who was right on that?
That was something I struggled with for a few years between roughly 2004 and 2009, and then in the U.S. Government when I became a bureaucrat from 2009 to 2012. That issue was front and center in a lot of our work. Justice issues became day-to-day practical issues of governance.
Forman: Were they referred to as justice issues at that time, or in the context of cost benefit?
Sunstein: Well, I worked on cost-benefit analysis as a lawyer as early as 1981, when I was a kid lawyer in the Justice Department, and there you're absolutely right. The environmental issues were focused, first and foremost, through the lens of cost-benefit analysis.
In 2009 we worked toward developing a social cost of carbon, which was the damage done by a ton of carbon emissions. There are lots of ways to think about that damage. One issue that was very much at the center of our deliberations was, do you use the global number or the domestic number?
So, if the United States contributes some number of tons of carbon in a year, is the damage done to just Americans living within the territorial boundaries of the United States? Or is the damage the total damage done to the world? You can see that as in part an issue of justice, and we certainly did.
Forman: Let’s discuss the social cost of carbon and its inputs. Are the costs the illnesses caused by poor air quality, extreme heat, etc.? Or does it look prospectively to consider issues such as accelerating desertification, lower crop yields, and more hunger? Or the costs of rising sea levels and the displacement of millions of people creating a migration crisis? Or rising deaths from more frequent and more intense storms or fires?
Sunstein: All of the above. If there's damage done from climate change in the sense that people are going to die from extreme heat, or if there's damage done from climate change in the sense that there's going to be flooding, which is going to cause property damage that certainly counts. If there's morbidity, short of mortality, where people are going to get sick that counts. It's basically everything that we can measure in terms of damage.
So, I think everyone will agree with what I just said. The social cost of carbon involves all of those things. The question that the Trump and Obama administrations disagreed about, and now the Biden and Trump administrations disagree about is, do we consider the domestic damage, or instead, the global damage done by a ton of carbon emissions? That really matters. Under Biden, the number was most recently in the vicinity of $190 per ton, and under Obama, it was $51 per ton. Under Trump 1.0 it was in the vicinity of $6 per ton. These striking variations between Trump on the one hand, and Biden and Obama on the other, are driven in large part because Trump chose the domestic damage, while Obama and Biden chose the global damage. There are other issues, but that is a really central one.
Forman: One of Biden’s first executive orders was to revert to the Obama $51 per ton. Later in his term with a broad consensus of inputs the number rose to $190 per ton effective February 2023. The benefits of this new assessment were in place for only the last year and a half of his term.
Sunstein: True. The EPA had the lead and the number came from the EPA. It was an internal government effort, of course, with attention paid to expertise outside of the government. The real work came from EPA, and of course, OIRA (the Office of Information and Regulatory Affairs), my old office also had a role in it.
The Obama administration number is based on three models of the damage done by climate change, and those were the best available models as of 2009, 2010, and 2011. There was an effort to use all of them, and not to play favorites, not to do one's own science. The number of $51 came out in 2015, and that was used throughout the remainder of the Obama administration. In the Biden Administration, as you say, the initial judgment was to go with the Obama number, not the Trump number, because of a theory that the Obama number was preferable both as a matter of science and better as a matter of what I’d call sound practice, that is to use the global damage, not the domestic damage.
Forman: In your book, you say judgment should not be political, the law and science matter, and you keep returning to that tenet throughout the book. On this issue of global versus domestic, you posit four different arguments. One is reciprocity. One is a John Rawls “do unto others” argument. You seem to side with the concept of global cosmopolitanism. Can you help me with that?
Sunstein: Yes, completely. How should we decide whether to use the global number or the domestic number? For one thing, the practical stakes are super high. The damage done to Americans by climate change is a fraction of the damage done to the world, so the social cost carbon is going to be a lot less. If you use the domestic number, it is not suggestive of the high stakes. If the number is little, then the benefits of regulations that reduce climate change are also little, that means it's going to be hard to justify stringency because you're not getting big benefits. So, the stringency of regulations, designed, let’s say, to reduce greenhouse gas emissions from cars and trucks and power plants, turns in significant part on the damage done by greenhouse gas emissions. And the damage done is a lot lower if we use the domestic number.
There are four arguments out there for using the global number. I think two of them are forceful, and two of them not so much so. The Trump administration, was correct to reject two of them; but the Trump administration was not correct to reject the two others.
So, the first of the incorrect arguments is that it's really hard to know what the domestic damage is. The science gives us more clarity on the global damage and it’s difficult to disaggregate and say this is the damage done to the US, this is the damage done to Canada etc. Given the current state of the science that's fair, but it doesn't justify use of the global number. Whatever the domestic number is, it's going to be some fraction of the global number, and we might use GDP or population or something to have an approximation. The fact that we don't know with clarity what the domestic damage done by a ton of carbon emissions doesn't justify using the global number, that would be overshooting the mark.
The second argument, and this is also an unpersuasive argument in my view, is that everything's interconnected, so that there are lots of Americans who don't live in the United States, and there are lots of American interests abroad, economic interests, security interests, etc. If the impacts of climate change get really bad there's going to be more migration, more pressure on the United States immigration system. And that suggests that using the domestic number will be too small because of the interconnectedness of the world. There's something truthful in that, which is we need an inclusive domestic number which includes the full range of damages done by climate change. But to say that is not to justify using the global number, because whatever the inclusive or appropriate domestic number is, it's a fraction of the global number. The argument for interconnectedness doesn't justify using the global number, though it does justify using a domestic number that attends to the full range of harms done by climate change to Americans.
Now to the two stronger arguments for using the global number. One speaks in terms of morality, and the other speaks in terms of national self-interest.
The one that speaks in terms of morality says, “Look, if Mexico emits pollution that kills people in Texas. It should take that on board, because people in Texas matter and for Mexico to be indifferent to the harm it's doing to people in Texas is morally wrong. If Canada is hurting people in Vermont, that should be stopped because people in Vermont matter and Canada should consider that. Consider this argument for the global number a matter of moral cosmopolitanism. It says, American economic activity that hurts people in other countries is a real hurt, even if the people live abroad, and we should consider that in deciding how much to scale back. That's the moral argument. I think it has a lot of force.
The fourth and final argument is about domestic self-interest. Here the idea is, if every country used the domestic number, then everyone's going to lose. If China just considers the harm done to China by its climate emissions, then Americans and Canadians and Italians and Germans are going to be hurt. What we need is an effort by the world to take on board the harm each of us does to people elsewhere. That's the only way for each of us to be protected against the risks associated with climate change. America's use of the global number is justified here, not on moral grounds, but on grounds of domestic self-interest, that we fuel and accelerate a process by which other countries take on board the harm they do to us, and that's something which Americans in the long run, and probably the short run, too, will benefit from.
Forman: Let’s touch a little bit on discount rates. Your premise in the preface of the book is the following statement “Here is my starting point. Each person should be counted equally, no matter where they live, and no matter when they live, and that you should respect and value the people of the future as much as you value them now.” I guess this is where the discount rate discussion gains relevance?
Sunstein: Completely. That's a very incautious statement by this particular author but I'm going to stand by it and not retreat from it. If you're born in Bangladesh, you don't matter less than if you're born in Los Angeles. And if you're born in 2060, you don't matter less than if you’re born in 1997. So that's the moral part of the book.
That's the foundation for morally upright thinking about the climate problem. With respect to the discount rate, it has the following implication, that if we do something that has, let's say severe negative effects on people in 2040, that's not less bad than if it had severe adverse effects on people in 2027. People in 2040 matter as much as people in 2027. That suggests we don't discount future harms on the ground that the people either aren't born yet or are young now, they count equally. We still should have a discount rate, I suggest, because most of us would rather have a dollar today than a dollar in 10 years, because we can invest that dollar and watch it grow.
The reason to discount future resources is that they're less valuable than current resources. And then there's a whole apparatus that helps us figure out the appropriate math. But the basic intuition is simple. We discount money because money in the future is worth less than money now. But we don't discount people because a person in the future is not worth less than a person now.
Forman: Let's shift over to a couple of the more prescient topics in the global context of climate change and nationalism as they manifest themselves every autumn in the Conference of the Parties (COP). We just had COP 29 in Azerbaijan last year, and the year before it was in Dubai. One of the most important topics at these two COPs was that of “loss and damage”.
I think most of our readers will understand the issue of stocks and flows (in the context of climate change), and that the stocks of GHG’s, have mostly come from the United States, with China the world’s largest current emitter soon to catch the United States on a cumulative basis as well. The most vulnerable societies of increased global warming are the least responsible for these harmful emissions. How would you like to address this disparity? In chapter 3, you suggest ways to remediate, or to look at this issue through the lens of corrective justice. How do we fix this problem?
Sunstein: Okay, let's start with the thought that if one person harms another that person owes the harmed person compensation for the wrong done, and cessation of the wrong being done. If someone is emitting pollution that’s causing health problems or property damage, the person should stop and the person should pay to compensate.
Now the insinuation that nations are similar to persons in the end, I think, is correct but it's complicated. This part of the book fusses a fair bit over the complications. Let me bore you a little bit with some of the fussing.
To think of who's the wrongdoer in the case of a nation is a little challenging, because some of the people who are responsible for the negative effects are dead; like my parents, regrettably, but they are dead. And they aren't going to be paying for the harm that they contributed. Now I'm continuing the fussing. Were they innocent in terms of their state of mind? They didn't intend to harm anybody. They didn't even know they were harming anybody. It's not as if someone is intentionally or knowingly imposing harm on people.
Some of the victims of climate change are people who have benefited enormously from American technological advances, perhaps those involving, health and economic growth.
Now America has benefited in part from the fact that they've bought those things. But some of the benefits have been given away for free, and some of the benefits haven't been paid for fully by the people who benefited. In principle, you'd want to subtract the benefits that we've given from the cost that we've imposed. I want to stop fussing and say that the basic assessment that when China imposes massive greenhouse gas emissions on vulnerable nations, it should pay and reduce; that intuition is correct. And it's also correct for the United States, which is the principal contributor to the stock, though not anymore to the flow.
Now, what exactly the right amount to pay gets very, very complicated, but I think what we want to start with is a moral judgment that those who are responsible for inflicting harms on others should help deal with the harms that they have caused.
Forman: We've come to the topic of common but differentiated responsibilities, which is a UN term. Would you like to talk about that for a second?
Sunstein: Yes. So, the idea of common and differentiated responsibilities is a bit of a of a political compromise. The idea is that “common” means we all have a responsibility to scale back. “Differentiated” means that how much we scale back is informed by the fact that some countries are a lot wealthier than others and some countries are a lot more responsible than others.
So, if you have a country that is poor and needs some use of coal to escape from poverty. What it is obliged to do is different from a country that, is wealthy and able, without extreme hardship, to shift from coal to greater reliance on solar and wind.
Common but differentiated responsibilities recognize differences in wealth, and differences in degree of development and recognize those things as relevant to what a nation should be required to do.
Forman: You have a very forceful end to this chapter. To quote: “But the fundamental point remains. Wealthy countries are more morally obliged to help poor countries manage climate-related risks. Substantial sums are in order to assist with emissions reductions, to promote adaptation, and to provide compensation for harms.” Very succinct and well-said, something I'm going to memorize.
Sunstein: Thank you for that. I can say parenthetically, and it might be useful for me to say that I reached that conclusion reluctantly. So, when I was initially writing the book I expected to say what I'd said in academic articles before, which was actually the contrary position that the corrective justice idea just didn't suit the climate change problem. It's too complicated. But I couldn't write with self-respect the view which I had formerly held. So, the sentences which I'm grateful for your mentioning, those sentences were kind of the product of an internal battle which I basically lost.
Forman: Thankfully. When thinking along the lines of how richer perpetrators of the climate crises can compensate the lower emitting “victims”, should we use the realities of United States ‘foreign aid’? Of course, this aid is now under attack, no greater victim than that close to home in the case of USAID.
Foreign aid in many instances takes the form of providing nations with arms, food stuffs, medicines, farm equipment, etc. most manufactured in our country. In essence an indirect subsidy of our manufacturers, farmers and industrial labor force. There is a circular flow of capital. I don't see this thinking in the case of climate assistance. Instead, when the topic of loss and damages comes up, the West or the United States take defensive postures.
Why isn’t the thinking, “We should send 100 billion dollars of United States manufactured green power generating assets or technologies such that these nations can bypass our hydrocarbon cycle and go straight to the less carbon intensive future we aspire to?”
Sunstein: It's a great question. So, you might think that USAID and its analogs in the U.S. Government are basically foreign aid providers. And you can celebrate that, or you can lament that, or you might think that some of what they do is a response to harms we've caused or that we've contributed to, rather than a matter of foreign aid. With respect to climate, in particular, the efforts to help nations adapt or become resilient against weather-related risks are best understood, not as a matter of foreign aid, but as a matter of corrective justice.
I think that's an important distinction. The United States has not been oblivious to the distinction and some of its policies with respect to mitigation, which means scaling back, or adaptation and resilience which means giving things that help countries be prepared have been done as a matter of pragmatism and prudence. I love your question. I should say that if we help countries use technologies that help them contribute less to the climate change problem, then we're helping them and we're helping the rest of the world as well. Because if the developing world is using less coal and more in the way of solar and wind, that's good for the world. That's a strong point in its favor. When we send technologies, or money that help them deal with extreme heat, some of which might be extremely simple such as nature-based solutions like tree planting and cooling centers; they don't help the world, it helps them.
How you provide the assistance, or redress, is again something where we would want the nation, the recipient nation, to be deeply engaged in, because they would probably know best. It’s best to be perceived not as a matter of foreign aid, but as having at least an element of corrective justice that can inspire. Something which is not charity, but a matter of desert.
Forman: Mentioning the word “adaptation” in a climate context used to result in a derisive accusation of one being a fossil fuel apologist, etc. This is a 1.5-degree warmed world headed to 2.5 degrees or more of warming, and we can model increasingly intensive storms, sea level rises, and the like. It would be unconscionable not to help people adapt to that.
Sunstein: Yes, thank you for that. I worked in the U.S. Government until November 2024; some full time, some part time. My role included climate, adaptation and resilience within the United States. I worked at the Department of Homeland Security, and one of my tasks was to help oversee and coordinate weather related adaptation and resilience. Now there's a government website with the National Risk Index. Last night I checked, and the site was still up.
I’m looking at the site right now, and I’m proud of our work. This type of resource shouldn't be something that Democrats and Republicans disagree about. It's about national hazard risk, and it provides information about where climate related risks are most severe and where the expected loss is. It allows you to distinguish among places where extreme heat is a big problem, places where tornados are a problem, places where flooding is a problem. It's a really helpful tool that provides people in the United States information such that they can adapt.
It is a tool that would be very useful on a global scale. So that if you live in, someplace in Pakistan or Somalia you’ll know where the risks are, and while forewarned isn't completely forearmed, if you don't have the resources to be forewarned, it’s tough to be forearmed.
And that is just one thing, getting people information. Another thing is getting people’s resources, including technology. There are some places in the world where it gets really, really, hot, and people don't die; places and people that have adapted to extreme heat. People just know what to do. If people in India could have the benefit of information and resources that could save many lives. So that in a harder world, a more volatile world in terms of weather, is not a more dangerous world. That sounds very ambitious. But let's just say that should be our goal.
Forman: Do we have an obligation to only invest in green energy infrastructure in poor countries, under the theory that we should encourage them not to replicate our “mistakes” with regard to emissions?
Sunstein: No. Consistent with the idea of common and differentiated responsibilities, telling people in poor countries they have to rely on more expensive or less effective forms of energy than we have relied on is much, too simple to say. We cannot say “We'll only help you with solar and wind to meet your energy demands.” The good news is that in many places in the world more nations see that less reliance on coal is economically sensible, and the hope is that in the not very long run that's going to be a general truth.
Forman: At the end of the book, you get back into familiar “Nudge” territory, or “Nudge 2.0” with the topic of choice engines. Can we change or influence the behaviors of consumers at scale to lead the way to a greener world? We're seeing a little bit of that now in insurance markets. We've also seen the success of financial incentives on electric vehicle sales and heat pump installations.
Sunstein: The general thought, and thank you for the connection with Nudge, is that what we buy is a function of what we know, and what we know isn't complete. If you learn, for example, that you can buy a refrigerator or microwave oven that is environmentally better, that's interesting to know. And if you learn that it's not only environmentally better, but it'll save you money over the course of the next 3 years, because it's energy efficient, that's also interesting to know.
So many of our choices with respect to what to eat and what to use in our home, we choose with imperfect information, so we just make a guess. And you can imagine the choice engines that are increasingly available. Large language models can be used as certain choice engines. They can help us make decisions. You can imagine, if one were a little bit concerned about climate, not a lot, one might want a choice engine that will tell you something about that. Or you could imagine that you're keenly interested in climate. And while you're not going to sacrifice your entire wallet for the sake of reducing greenhouse gas emissions, you'll sacrifice something. Or maybe you'll be in search of something that is not going to cost you but is just better in terms of climate.
Maybe it's a product that's new and you didn't know about it. The fact is that you can imagine neutral “just the facts, ma'am”, choice engines that can help people save money and be a little cleaner, or you can imagine more. Let's say, directive choice engines that will give you clarity about the environmental consequences and kind of trigger your conscience. The fantastic thing is that while each of us makes choices that don't affect the whole planet, if you get a lot of people in India or in France making decisions that are a little bit better environmentally, then the reduction of greenhouse gas emissions can be very significant. All because of the large number of people who are making small climate, friendlier choices nudged by choice engines. I'm hoping this is a wave of the future and will be a way to help people save a little money and also be a little better to their grandchildren.
Forman: In conclusion, I just want to commend you. There are, if you Google it, over a hundred books, with the name, or sub-title, “Climate Justice” in one shape or form. The subtitle of this book is “What rich nations owe the world and the future”. This aspect of climate justice is not often broached. There are climate justice issues with respect to societal socioeconomic differences. There are indigenous persons climate justice issues. Mary Robinson, the former Prime Minister of Ireland had a famous Climate Justice book published in 2019. Your book gets into the nuts and bolts, and the complexities of the nation/state level issues. It's well-footnoted and researched. Facts do matter.
Sunstein: Well, thank you for that. It was a book of art and head, and it took me longer than I could possibly have imagined. It took me roughly 20 years.
Forman: Marshall Ganz would be proud of you as it is a “story of self”. You took a journey, and you came out where you didn't think you would. As I remember, you mention at the beginning of this book another book that you were going to co-author in 2008 or 2009. The incoming Obama Administration said, we don't want your name on that book because it's counter to what we are trying to do policy wise. The book was published without your name, and then you undertook the evolution to this book. I believe you disavow a lot of the conclusions made in that original book.
Sunstein: That is completely right, and I'm going to try not to be embarrassed by the errors of my younger self.
Forman: Right, your youthful indiscretions. We're all allowed those Cass, and thank you so much, and keep up the good work and continued evolution. This is the most challenging environment that we've had in a long time. We need people like you to help us, show us pathways to a better, more just world. Thank you.
Sunstein: It feels a little like doing a book on folk music, two weeks after Dylan went electric. I hope this is not the book’s legacy.
About the Author
Keith Forman is a 2020 Harvard Advanced Leadership Initiative Fellow with over four decades of experience in leadership positions in the energy industry. He currently serves as the Chairman of Capital Clean Energy Carriers, a shipping company based in Greece. Over the years, he has advised global infrastructure and private equity funds on midstream energy investments, served as the CEO for renewable energy companies, and held positions as a senior financial executive in large midstream energy companies.
This Q&A has been edited for length and clarity.
Cover Photo Credit: By Freepik