Emission reduction targets and outcomes of the Clean Development Mechanism (2005–2020)

The Clean Development Mechanism (CDM) allows developing countries to earn carbon credit units by reducing greenhouse gas emissions. Here we assess the emission reduction outcomes of the CDM between 2005 and 2020. The analysis covers 3,311 CDM projects hosted by 79 countries and over 10,000 Monitoring Reports. We identify which host countries and project types departed from original forecasts more. Overall, the total amount of actual emission reductions was 16% below the targets envisaged by project proponents. Emission reduction projects consistently under-performed over the year, but performance varied between and within regions. Industrial HFCs and N2O projects exceeded their targets, whereas landfill gas and methane avoidance projects under-performed by larger margins. Economic gains were unevenly distributed. Estimated revenues relative to GDP were higher for larger emerging economies, and disproportionately smaller for the deprived members of the Global South. Four host countries (China, India, South Korea and Brazil) not only dominated the market, but also gained an advantage from the higher carbon prices before 2012. Least Developed Countries had their carbon credits issued in more recent years when prices were much lower. The results show an imbalance in economic outcomes and raise questions about the effectiveness and equity of this Kyoto mechanism. Weak targets under Paris Agreement could intensify these challenges.