New emissions trading systems have been and still are emerging around the world. Without implementing international structures, trading certificates generated from project-based mechanisms as the CDM will become more and more difficult. In this discussion paper on behalf of the German Emissions Trading Authority within the Federal Environment Agency, adelphi's experts on emissions trading, Aki Kachi and Dennis Tänzler, together with Wolfgang Sterk of the Wuppertal Institute, analyse options for a further development and the future potentioal of the CDM.