Supplementarity

'Supplementarity', also referred to as 'the supplementary principle', is one of the main principles of the Kyoto Protocol. The concept is that internal abatement of emissions should take precedence before external participation in flexible mechanisms. These mechanisms include emissions trading, Clean Development Mechanism (CDM), and Joint Implementation (JI). 'Supplementarity', also referred to as 'the supplementary principle', is one of the main principles of the Kyoto Protocol. The concept is that internal abatement of emissions should take precedence before external participation in flexible mechanisms. These mechanisms include emissions trading, Clean Development Mechanism (CDM), and Joint Implementation (JI). Emissions trading basically refers to the trading of emissions allowances (carbon credits) between one regulated entity and a less pollutive entity. This trading of permits results in a marginal economic disincentive to the buyer and a marginal economic incentive the abater. CDM and JI are flexible mechanisms based on the concept of a carbon project. These projects reduce GHG voluntarily (outside the capped sectors) and therefore can be imported into the capped sector to aid in compliance.