Decentralized voluntary agreements do not reduce emissions in a climate change experiment

Can climate accords based on decentralized and voluntary agreements successfully reduce carbon emissions? We designed an economic experiment to study the effectiveness of the best-known mechanisms to foster international cooperation on climate change mitigation: climate pledges, financial penalties, and peer evaluation. We test each mechanism both separately and together. In the climate pledge treatments, participants could pledge their desired emissions target, approved by majority vote. In the treatments with financial penalties, failure to meet pledges triggered monetary sanctions. In the peer evaluation treatments, participants could evaluate each other, which determined who would receive an additional nonmonetary environmental prize. We find that most participants joined climate agreements and met their pledges, but pledges were insufficiently ambitious. As a result, neither pledges, financial penalties, nor peer evaluation reduced emissions. These results question the effectiveness of decentralized and voluntary climate agreements, such as the Paris Agreement.