Article 6 of the Paris Agreement introduces provisions for using international carbon market mechanisms to fulfil nationally determined contributions (NDCs). One of these includes the use of internationally transferred mitigation outcomes (ITMOs) under Article 6.2. One possibility for implementing Article 6.2 is that countries could use existing carbon markets – e.g. existing crediting schemes and emissions trading schemes (ETSs) – as the basis for certifying the mitigation outcomes that are traded internationally. Fundamental to the success of these cooperative mechanisms is the concept of environmental integrity, implying that the use of cooperative mechanisms should not result in increased global emissions compared to a scenario without such cooperation.

This paper addresses the question of unit quality for carbon offset credits. Unit quality is defined to mean that the issuance or transfer of one unit, expressed as 1 tCO2e, is associated with an emission reduction of at least 1 tCO2e in the transferring country, compared to the situation in the absence of the carbon market program.

The authors propose a framework for evaluating the standards and practices of crediting schemes and presents the preliminary results from applying this framework to six existing schemes.