Joint implementation and uniform mixing

Joint implementation is a hotly debated issue in the context of the Framework Convention on Climate Change. The main argument for joint implementation is that, since it does not matter where greenhouse gas emissions are reduced (as these gases mix uniformly in the atmosphere), it is better to do it where abatement is cheapest. Many objections to joint implementation exist. Here we add one that argues against the uniform mixing property. Although in the long run the global climate is insensitive to the place where abatement is undertaken, in the short run the regional climate changes with the induced changes in the albedo. Indeed, reduction of the atmospheric load of sulphate aerosols and albedo changes associated with land cover change may well lead to accelerated warming in the region of abatement. This is undesirable as the rate of climatic change is a major determinant of the damage done. Hence, the discussion on joint implementation is further complicated.