Climate change is an ethical issue, because it involves the distribution of a scarce resource-the capacity of the atmosphere to absorb our waste gases without producing consequences that no one wants. Various principles might be used to decide what distribution is just. This commentary argues that on any plausible principle, the industrialised nations should be doing much more than they are doing now, and much more than they are required to do by the Kyoto protocol, to reduce their greenhouse gas emissions. The commentary also responds specifically to some issues raised by MacCracken, Toman and Gardiner, including feasibility, the discount rate, and grounds for pessimism.
