The European Union has been a pioneer in combating global climate change through its emissions trading system (ETS), which puts a price on greenhouse gas emissions by assigning emissions allowances that can be traded within the EU. But most other large countries do not price carbon, thereby placing EU industry at a disadvantage. A new study carried out by a team of CEPS experts in trade and climate change, led by Daniel Gros and Christian Egenhofer, explores the question whether it would make sense for the EU to impose a ‘carbon border tax’?