In this chapter we first discuss the main principles of justice and note the standard objections to them, which we believe necessitate a hybrid approach. The hybrid account we defend is primarily based on the distributive principle of sufficientarianism, which we interpret as the idea that each country should have the means to provide a minimally decent quality of life for each of its citizens. We argue that sufficientarian considerations give good reason to think that what we call the ‘ability (...) to pay objection’ should be taken much more seriously in this debate. Following this, our account emphasises what we believe are the two most important moral desiderata in any attempt to distribute responsibility for dealing with climate change: the ability to mitigate the problem and the making of culpable contributions to the problem. After noting that our proposal includes enough detail to be a useful start for policy makers, we defend our account against some potential objections. (shrink)