Cass R. Sunstein is a Bloomberg Opinion columnist. He is the author of “The Cost-Benefit Revolution” and a co-author of “Nudge: Improving Decisions About Health, Wealth and Happiness.” Read more opinion SHARE THIS ARTICLE Share Tweet Post Email

Photographer: Munir Uz Zaman/AFP/Getty Images Photographer: Munir Uz Zaman/AFP/Getty Images

There is unprecedented momentum for a real international agreement at the Paris climate talks in December: The U.S. is on track to make significant cuts in greenhouse-gas emissions, China has announced a cap-and-trade program and many others have made commitments of their own.

The biggest obstacle? Justice -- or at least two ideas about justice.

QuickTake Climate Change

The first involves redistribution. As part of any agreement, poor nations, such as Brazil and India, want wealthier countries to pay them a lot of money, both for scaling back their emissions and for adapting to a warming climate.

Their argument has traction. Wealthy nations have agreed, in principle, to provide $100 billion by 2020 to the United Nations’ Green Climate Fund. Last year, President Barack Obama pledged to give $3 billion. (Disclosure: My wife, Samantha Power, is the U.S. ambassador to the UN.) Recently China announced that it would give another $3.1 billion, and Prime Minister David Cameron said that the U. K. would give $8.8 billion. But both Obama and Cameron face significant opposition from their national legislatures -- and in Paris, poor nations seem poised to demand far more, perhaps even trillions.

Are those demands justified? Rich countries have a lot of poor people too, and they face multiple demands on their budgets. Though developed nations can be spectacularly generous, they are likely to resist giving many billions of additional dollars in foreign aid. And if the real goal is to help poor nations, the argument for specific funds to combat climate change seems weaker than the argument for a general cash grant, which poor countries could use however they like (for example, to combat malaria).

But poor countries have a second and perhaps more compelling idea: corrective justice. In particular, they call for “reparations,” a term used over the weekend by Indian Environment Minister Prakash Javadekar.

Their contention is that rich nations, which created the problem of climate change, have an obligation to fix it, not least by providing compensation for the high costs that, in their view, global warming has already imposed. Their argument adds that rich countries have gotten rich as a result of cheap energy (mostly coal); poor countries should be paid if they are to be deprived of the same opportunity.

That isn't entirely crazy, but like other arguments for reparations, it runs into serious objections. For one thing, it depends on notions of collective responsibility. Most people in wealthy nations -- whether rich or poor, or whether American or British or German -- did not intend, and are not personally responsible for, the harms faced by citizens of India. Are they nonetheless obliged to pay reparations?

The corrective justice argument also conflates current generations with past generations. Much of the current “stock” of greenhouse gas emissions was produced by the actions of people who are now dead. The median American was born in 1979. How, exactly, does he or she owe reparations to people now suffering from warmer climates in India, Vietnam or Bangladesh?

There is a subtler problem. Through industrial activity, trade, and technology, rich countries have conferred big benefits on poor ones, not least in the form of improved health and opportunity. Consider the recent response to the Ebola crisis, life-saving medical innovations or the dissemination of cell phones throughout the world.

A full accounting might require poor countries to pay the rich ones back for those benefits. No one in rich nations is asking for any form of restitution. (And they shouldn’t.) But if we are really interested in measuring who has helped and hurt whom, a claim for reparations puts the issue on the table.

Some poor countries might respond that they are facing a catastrophic threat against which they cannot easily protect themselves and for which they are not responsible. They might add that even if people in wealthy nations didn't intend to harm anyone, their own standard of living is a direct product of the coal and oil used to build national economies.

That’s not the worst response. But the causal chains here are difficult to untangle; which acts of which nations are responsible for what kind of harm, exactly? At the very least, the ordinary framework for corrective justice (one person injures another, and so must pay) doesn't quite apply.

It is possible, of course, to combine arguments from redistribution and corrective justice in support of the conclusion that as part of a climate change agreement, wealthy nations should be prepared to meet their $100 billion pledge, or even to add to it. Because emissions from poor nations (including India) are rapidly growing, and because a worldwide agreement requires broad participation, wealthy nations have their own incentive to sweeten the pot.

Whether or not the moral arguments of poor nations are convincing, there is a cruel irony. If the economic demands of those nations are exorbitant, they will present serious obstacles to an effective agreement -- and if such an agreement cannot be reached, the world’s poorest nations will be the world’s biggest losers.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

To contact the author of this story:

Cass R Sunstein at csunstein1@bloomberg.net

To contact the editor responsible for this story:

Christopher Flavelle at cflavelle@bloomberg.net