Can voluntary carbon emission reduction pledges, such as the nationally determined contributions under the Paris Agreement, result in significant emission reductions? According to prominent experts such as Nordhaus (2015), Barrett (2005), and Weitzman (2019), free-riding is unavoidable in cooperative situations based on voluntary agreements. If their assessments are correct, each country’s nationally determined contribution is unreliable. Countries will strategically promise large cuts while making only minor emission reductions.