This article analyses the implementation of emissions trading systems (ETSs) in eight jurisdictions: the EU, Switzerland, the Regional Greenhouse Gas Initiative (RGGI) and California in the US, Québec in Canada, New Zealand, the Republic of Korea and pilot schemes in China. The article clarifies what is working, what isn't and why, when it comes to the practice of implementing an ETS. The eight ETSs are evaluated against five main criteria: environmental effectiveness, economic efficiency, market management, revenue management and stakeholder engagement. Within each of these categories, ETS attributes − including abatement cost, stringency of the cap, improved allocation practices over time and the trajectory of price stability − are assessed for each system. Institutional learning, administrative prudence, appropriate carbon revenue management and stakeholder engagement are identified as key ingredients for successful ETS regimes. Recent implementation of ETSs in regions including California, Québec and South Korea indicates significant institutional learning from prior systems, especially the EU ETS, with these regions implementing more robust administrative and regulatory structures suitable for handling unique national and sub-national opportunities and constraints. The analysis also shows that there is potential for a 'double dividend' in emissions reductions even with a modest carbon price, provided the cap tightens over time and a portion of the auctioned revenues are reinvested in other emissions-reduction activities. Knowledge gaps exist in understanding the interaction of pricing instruments with other climate policy instruments and how governments manage these policies to achieve optimum emissions reductions with lower administrative costs. Key policy insights. Countries are learning from each other on ETS implementation.. Administrative and regulatory structures of ETS jurisdictions appear to evolve and become more robust in every ETS analysed.. A 'double dividend' for emissions reductions may also exist in cases where mitigation occurs as a result of the ETS policy and when auction revenues are reinvested in other emissions-reduction activities.

Carbon pricing is a key policy instrument used to steer markets towards the adoption of low-carbon technologies. In the last two decades, several carbon pricing policies have been implemented or debated at the state and federal levels in the US. The Regional Greenhouse Gas Initiative and the California cap-and-trade policy are the two regional policies operational today. While there is no federal policy operational today, several carbon pricing proposals have been introduced in Congress in the last decade. Using the literature on interest group politics and policy entrepreneurship, this article examines the carbon pricing policies at the subnational and federal levels in the US. First, the article explores the evolution of two main regional carbon pricing policies, the Regional Greenhouse Gas Initiative and California cap-and-trade, to identify how interest groups and policy entrepreneurs shaped the design and implementation of the respective policies. Second, the article details the federal carbon pricing policy proposals and bills discussed in the last decade. Third, it examines the factors that limit the prospects of realizing an ambitious federal carbon price for pursuing deep decarbonization of the US economy. The article finds that federal carbon pricing in the US suffers from the lack of any natural and/or consistent constituency to support it through policy development, legislation, and implementation. While interest group politics have been mitigated by good policy entrepreneurship at the subnational level, the lack of policy entrepreneurship and the changing positions of competing interest groups have kept a federal carbon pricing policy from becoming a reality.