Putting a price on carbon is critical for climate change policy. Increasingly, policymakers combine multiple policy tools to achieve this, for example by complementing cap-and-trade schemes with a carbon tax, or with a feed-in tariff. Often, the motivation for doing so is to limit undesirable...

The three Kyoto flexible mechanisms emissions trading, the clean development mechanism (CDM), and Joint Implementation (JI) have always been controversial. Proponents saw the mechanisms as clever tools to ensure environmental outcomes were achieved at least cost. Reducing the costs of...