There is agreement internationally that responsibility for reducing emissions should be equitably shared, but debate about the principles for determining equitable shares frequently focuses on the distribution of emissions rights. This shift of focus from responsibilities to rights is not necessarily conducive to reducing emissions. There is reason for caution, particularly, regarding suggestions that emissions rights should be assimilated to human rights. Concerns about the situation of the worst off globally have led to calls for recognition of a human right to some baseline amount of emissions per capita in order to secure subsistence. However, given the reasons to support a human right to an adequate environment, it would be a mistake to recognize any human right to pollute. What the worst off have a right to is secure access to the means to a decent life. Arguing that issues of both emissions and subsistence should be comprehended within a single framework of justice, the proposal here is that this broader framework be developed by reference to the idea of “ecological space.” An equitable distribution of rights to ecological space would in principle ensure an equitable distribution of welfare goods without sanctioning any excess use of natural resources or environmental services, including the planet’s capacity for absorbing carbon.