Emissions trading systems (ETSs) are operating and developing in many regions and countries. Doubts have been raised about their effectiveness, but the global picture has many nuances, as the contributions to this thematic issue on carbon markets show. The cases examined in this special issue include carbon markets rules under the Paris Agreement, the reform of the EU ETS and the proposed expansion of its sectoral coverage to shipping, and emissions trading initiatives in China, the USA, and New Zealand. The evidence indicates that, despite uncertainties related to future developments, carbon markets are continuing to evolve and expand around the world.