Policy implications of potential conflicts between short-term and long-term efficiency in CO2 emissions abatement

This paper shows that, under certain conditions (including path dependence and lock-in), policies and measures leading to a cost-effective GHG emissions mitigation in the short term may not allow reaching long-term emissions targets at the lowest possible cost, that is, they might not be cost-effective in the long term. The reason is that, in a situation where currently expensive technologies have a large potential for cost reductions through learning effects and R&D investments, the implementation of incentive-based mitigation policies such as taxes or tradable permits will encourage the adoption and diffusion of currently low-cost abatement technologies, but might not be enough to make attractive the diffusion of expensive ones, which is a necessary condition for these technologies to realise their cost-reduction potential through the aforementioned effects. A simple model and a numerical simulation are provided to show this possible conflict between static and dynamic efficiency, which points out to the need to combine different instruments, some aiming at short-term cost-efficiency (such as incentive-based environmental policy) and others at encouraging dynamic cost reductions (such as technology/innovation policy).