A harmonized worldwide carbon tax, implemented at regional or national level, can be enforced only with an international collective action which takes into account inherent interests of all countries. The purpose of this study is to assess the impact ofthe implementation of such a tax by means of different scenarios based on realistic assumptions. We endeavor to design a world tax on anthropogenic greenhouse-gases emissions which can be politically acceptable and technically feasible. To do so, we also address international equity through lump-sum transfer and transfers based on countries’ financial capacity. Part of the Report 'The Feasibility of a World-wide Tax on Anthropogenic Emissions of Greenhouse Gases' for the Federal Office of the Environment