This paper explores the interactions of international policy architecture and technology availability on the limitation of atmospheric CO2 concentrations to 500 ppm in the year 2095. We find that technology is even more important to reducing the costs of emissions mitigation when international policy structures deviate from immediate and full participation. We also find that the international diffusion of climate technology may be as or more important to domestic mitigation cost containment as domestic technology diffusion. We observe that near-term carbon prices reflect in a very direct way expectations about technology a half century and more into the future. We find that the policy architecture has a relatively modest effect on global emissions limitation pathways when compared with the impact of technology availability and observe that more rapid technology improvements reduce the relative influence of the policy architecture. Finally, we consider the implications combining CO2 capture and storage technology with bioenergy production, namely electricity production with negative carbon emissions.