Nations are regularly considered the main bearers of responsibility for climate change. Accordingly, the differences between nations are crucial in understanding how responsibilities should be distributed. In this account, I examine the relevance of differences in type of political regime to this end. The claim defended here is that democratic institutions are constitutive of the conditions for when members of nations can be held responsible as a collective for the outcomes affecting the climate. The implications of this account are demonstrated, first, in relation to claims of historical responsibility and, second, in relation to the burdens assigned to Annex I countries by the UN Framework Convention on Climate Change. The analysis shows why democratic institutions – at present and in the past – are essential in order to conclude that the members of a nation share responsibility for the harm caused by the aggregate greenhouse emissions of their nation. In connection to this analysis, we also show why responsibility for the costs of climate change is sometimes justly placed on authoritarian nations.