Carbon markets are considered a key policy tool to achieve cost-effective climate mitigation1, 2. Project-based carbon market mechanisms allow private sector entities to earn tradable emissions reduction credits from mitigation projects. The environmental integrity of project-based mechanisms has been subject to controversial debate and extensive research1, 3, 4, 5, 6, 7, 8, 9, in particular for projects abating industrial waste gases with a high global warming potential (GWP).

This study systematically evaluates the environmental integrity of Joint Implementation (JI) in the first commitment period of the Kyoto Protocol. Analysis indicates that about three-quarters of JI offsets are unlikely to represent additional emissions reductions.

This Technical Note provides a summary of the key elements and design features of 11 different carbon offset programs. It discusses the essential differences and similarities between programs, and discusses how these programs address key issues, such as: efficiency, environmental integrity, applicability, and transaction costs.