This paper deals with global mitigationstrategy. More specifically the main purpose is to addressthe question of whether growth in the developing world isconsistent with long?run climate change objectives. Thefirst part of this paper lays out time paths for emissionsfor countries in various categories. These paths areconsistent with countries' growth objectives, incomes,and capacity to absorb mitigation costs. The intent is toshow that while global emissions are likely to remain flator even to rise as a result of the combined effect ofmitigation undertaken by advanced countries and growth inthe developing world, eventually reasonably safe global percapita levels can be reached on a 50?year time horizon. Thesecond part of this paper discusses countries' roles inrelation to different categories and mechanisms that willsupport the achievement of safe emissions paths. Thesemechanisms create incentives and deal with the absorption ofcosts. In particular, the paper argues that a carbon credittrading system in the advanced countries, combined with aneffective cross?border mechanism and a'graduation' criterion for developing countries tojoin the advanced group, will create strong incentives,achieve a fair pattern of cost absorption, and support thedynamics described in part one. One point emerges clearly:the cross?border mechanism (or international offsets) isessential in dealing with both the efficiency and the costabsorption and equity challenges of a global mitigation strategy.