Europe is providing a test of whether weak governments can enact strong policies. It has set firm goals to reduce carbon emissions by at least 55% by the end of the decade, before becoming carbon-neutral by 2050. European Union governments have agreed on the strategy, but they tend to paper over the short-term economic costs of the green transition. If they don’t come clean to public opinion, and explain how these costs will be shared, they may face crippling populist protests that will compromise their end goals.