Climate change must deal with two market failures: global warming and learning by doing in renewable use. The first-best policy consists of an aggressive renewables subsidy in the near term and a gradually rising and falling carbon tax. Given that global carbon taxes remain elusive, policy...

Economic theory suggests that with a pollution externality and learning spillovers related to renewable energy technologies, the optimal climate policy mix includes an emissions policy and an output subsidy to the learning industry. Instead of output subsidies, feed-in tariffs are often...