Critics of carbon mitigation often appeal to what Jonathan Glover has called ‘the argument from no difference’: that is, ‘if I don’t do it, someone else will’. Yet even if this justifies continued high emissions by the industrialised countries, it cannot excuse business as usual. The North’s emissions might not harm the victims of climate change in the sense of making them worse off than they would otherwise be. Nevertheless, it receives benefits produced at the latter’s expense. This enrichment is unjust; unjustly-enriched agents ought to make compensation. The best form of compensation is vigorous action against climate change.