Where this document refers to “countries” or “governments”, it is also intended to include “regional economic organisations”, if appropriate. The authors would like to acknowledge helpful comments from OECD and IEA colleagues Jane Ellis, Simon Buckle, Christina Hood, Raphael Jachnik, Lauren McNicoll, Mariana Mirabile, Andrew Prag, Guillaume Simon and Manasvini Vaidyula. The authors would also like to thank delegates to the September 2017 CCXG Global Forum on the Environment and Climate Change for their comments on earlier versions of this paper, in particular delegates and experts from the following countries and organisations: Australia, Brazil, Chile, Moldova, Mexico, Indonesia, Japan, Republic of Korea, Singapore, CITEPA, ICAT, ODI, UNDP and UNFCCC Secretariat.