Climate Justice in Theory and Practice

Everyone knows, or should know, that climate change is helping to create horrors: flooding, wildfire, extreme heat, drought, and much more. What such words do not adequately capture are the concrete harms: deaths; illnesses; losses of jobs, income, and opportunity; fear, stress, and sometimes terror.

While no one is immune from the risks of climate change, some people, and some nations, are far more vulnerable than others. People in Pakistan face greater risks than do people in Canada. People in Afghanistan are much more vulnerable than are people in Sweden. People in Chad are much more vulnerable than are people in Germany. People in Somalia, the Democratic Republic of Congo, Nigeria, and Ethiopia are much more vulnerable than are people in France, Denmark, and the United States.

It is also clear that some nations have contributed far more to the problem of climate change than others. The United States wins the prize for all-time greatest contributor. China is, by far, the greatest annual contributor. It follows that people in some countries will experience untold suffering and that people in other nations are largely responsible for that.

As of this writing, the world’s top five emitters are the United States, China, Russia, Brazil, and India. Since 1990, their emissions have been estimated, on one account, to have produced a staggering $6 trillion in income losses, which is comparable to 11 percent of the annual global gross domestic product. Let us pause over that estimate without necessarily crediting it. Whatever we think of any particular set of numbers, no one doubts that the largest emitters are mostly responsible for the losses. Importantly, the distribution of those losses is highly unequal. A disproportionate amount is borne by low-income, low-emitting countries. The high-emitting countries have gained a lot from their emitting activities and have lost relatively less.

How should we think about that?

Here is my starting point: each person should be counted equally, no matter where they live, and no matter when they live. That claim, appropriately qualified, has implications for an assortment of concrete policies related to climate change.

I take my inspiration here from John Stuart Mill, who emphasized that utilitarianism, his preferred approach to ethical questions, does not call for selfish behavior and indeed does not even authorize it. In Mill’s account, the “utilitarian standard of what is right in conduct, is not the agent’s own happiness, but that of all concerned.” Having said that, Mill started to soar: “As between his own happiness and that of others, utilitarianism requires him to be as strictly impartial as a disinterested and benevolent spectator. In the golden rule of Jesus of Nazareth, we read the complete spirit of the ethics of utility. To do as you would be done by, and to love your neighbour as yourself, constitute the ideal perfection of utilitarian morality.”

In the context of climate change, it is probably too much to expect people to “love” their neighbors as themselves. But it might not be too much to ask people to aim to do as they would be done by. (I have not mentioned nonhuman animals, but they matter too. On that one, let’s stomp our foot a bit. Harms to nonhuman animals must be counted in the overall assessment of the welfare effects of climate change, though I will not have much to say on that important topic here.)

There are cautionary notes, of course—some of them involving self-interest, some of them involving people’s moral intuitions, some of them involving what is practical. Most important, perhaps, is nationalism. I love the United Kingdom, for example, and I am lucky enough to have an affiliation with one of its great universities, but the people of that admirable nation do not think that their responsibility to the people of Ethiopia is equivalent to their responsibility to the people of the United Kingdom. Nationalism raises a host of hard questions, and we shall explore some of them here. For the record: I do not oppose nationalism as such. Still, the ethics of nationalism is inconsistent with the spirit of the ethics of utility and with the golden rule of Jesus of Nazareth.

Ethical issues are closely intertwined with strategic issues. When rich countries ask poor countries to do more to reduce their emissions, poor nations might well say: “If you want us to do that, you will have to pay us.” Or: “You caused the problem, and got rich in the process, and now you want us to solve the problem? Wow. How much is that worth to you?” Rich countries might well respond: “We are all in this together, and you are more at risk than you think. Actually, you are more at risk than we are. Let’s find a reasonable path, without your demanding massive subsidies, which will derail the whole effort!”

THEORY AND PRACTICE

My central conclusions are straightforward:

1. The nations of the world should use the global figure for the social cost of carbon, not the domestic figure. Moral cosmopolitanism, in the constrained form defended here, is sufficient to justify that view. If one nation harms another, it should take that harm into account in deciding what to do.
2. The argument from reciprocity appeals not to morality but to domestic self-interest; it emphasizes that if every nation used the domestic figure, all nations would lose. That argument is convincing. There are no guarantees, of course, that if the United States uses the global number, or if Sweden or Denmark does, other nations will follow suit. But a norm in favor of use of the global number is exceedingly important, and a nation that chooses to use that number can contribute to the creation of the necessary norm. It is worth noting that the argument from moral cosmopolitanism and the argument from reciprocity tend to converge.
3. On welfarist grounds, a degree of redistribution from wealthy nations to poor nations is an excellent idea. A central reason is that a given amount of money is worth a lot more to a poor person than to a wealthy one. If a poor person receives $10,000, it can make a massive difference; if a rich person receives $10,000, it might make no difference at all. It follows that when such redistribution occurs, poor nations are likely to gain more in terms of welfare than wealthy nations are likely to lose. Apart from that point, there is a good argument that a degree of redistribution is justified from the standpoint of distributive justice.
4. With respect to climate change, these points are complemented by a point about corrective justice. By emitting greenhouse gases, wealthy nations have imposed risks on poorer ones. It is true that in the context of climate change, there is an assortment of problems with both distributive justice and corrective justice arguments. Matters here are intriguingly more complicated than they seem. Even so, those arguments are more right than wrong. Rough justice is still justice.
   
5. People who are alive now do not deserve greater attention and concern than people who will be born twenty years hence, or forty years hence, or a hundred years hence. Nations should follow a principle of intergenerational neutrality. It is necessary to produce an appropriate discount rate. Discounting the costs and benefits of taking action to prevent climate change may initially seem like a technical, mathematical issue, but it turns out to be one of the central ethical issues in evaluating climate change. Seemingly small changes in the discount rate can lead to very large changes in estimates of the costs of climate change and the benefits of abatement. With a very high discount rate, the argument for immediate, aggressive action to reduce climate change seems weak. With a near-zero discount rate, that argument seems overwhelmingly strong. It does not follow, however, that the discount rate should be zero. Money can be invested and made to grow. If our ancestors used a zero discount rate, we would be a lot worse off than we are now. […] As of this writing, a discount rate in the general vicinity of 2 percent makes sense. If that seems a bit tedious, note well: this point cautions against a discount rate of 5 percent or 7 percent, which some people have advocated, and also against a discount rate near or below 1 percent, which other people have advocated. The stakes are very high.

My focus has largely been on theoretical questions and on matters of right and wrong. But everyone knows that there are limits to how much wealthy nations are willing to do, both in scaling back their emissions and in providing assistance for adaptation. The United States does not want to give a large percentage of its GDP for climate change adaptation, nor do China, the United Arab Emirates, France, Germany, and Canada. Insistence on what is right and what is wrong might derail agreements that are in the interest, above all, of the very nations that are most vulnerable to climate change. That is potentially tragic. International agreements and grants of foreign aid are a product of an unruly mixture of national self-interest and morality.

Still, no one should underrate the importance of ethical judgments, which provide the background against which public officials and negotiators do their work. Those judgments are sometimes a cloud, but they can also be a shining star.

Adapted from Climate Justice What Rich Nations Owe the World—and the Future by Cass R. Sunstein. Reprinted with permission from The MIT Press. Copyright © 2025.