ABSTRACT
The ideal response to the considerations on the part of sub-national communities would be to play their assigned roles in an adequate national-level response to climate change. A national-level response of this sort would almost certainly be fairer and more effective than unilateral action at the sub-national level. This chapter briefly and informally recapitulates the positive case – set out in detail in Umbers and Moss – in favour of the claim that many sub-national political communities have duties to take unilateral steps to reduce their emissions, where the states to which they belong fail to adopt adequate national-level emissions-reduction policies. It is uncontroversial that many nations have duties to reduce their emissions to help mitigate the threat posed by climate change. Theorists who have discussed unilateral climate action at the sub-national level – including those generally supportive of such action – often point out that such policies also risk causing carbon leakage.
