Climate change and its harmful effects are widely accepted. A common approach is to argue along the lines of Mill's ‘harm principle’: if we contribute to climate change, then we are likewise responsible for harming others and we have a negative duty to reduce our carbon emissions. This article argues that a negative duty leads to a philosophical fork in the road which does not necessarily entail carbon emissions reductions. Arguments for such reductions require further supplementation to close off possible non-conservationist alternatives.