We examine international cooperation on technological development as a supplement to, or an alternative to, international cooperation on emission reductions. R&D should be increased beyond the non-cooperative level if (i) the technology level in one country is positively affected by R&D in other countries, (ii) the domestic carbon tax is lower than the Pigovian level, or (iii) the domestic carbon tax is set directly through an international tax agreement. A second-best technology agreement has higher R&D, higher emissions, or both compared with the first-best-outcome. The second-best subsidy always exceeds the subsidy under no international R&D cooperation. Further, when the price of carbon is the same in the second-best technology agreement and in the case without R&D cooperation, welfare is highest, R&D is highest and emissions are lowest in the second-best R&D agreement.
climate policy international climate agreements R&D policy technology spillovers