Carbon accounting for sinks in the CDM after CoP-9
The role of sinks in the clean development mechanism (CDM) has been a subject of controversy for several reasons; one being that temporary carbon storage in forests appeared to prevent any opportunity to use them as an option to reduce permanent greenhouse gas (GHG) emissions. In Milan (December 2003), the Conference of the Parties (CoP) decided to address this problem by introducing two types of expiring units: temporary CERs (tCERs) and long-term CERs (lCERs). Countries committed to emission reductions may acquire these units to temporarily offset their emissions and thus to postpone permanent emission reductions. As further decided by the CoP, baseline emissions of GHGs and the enhancement of sinks outside the project boundary will not be accounted for in the calculation of tCERs or lCERs. The contribution of CDM-sink projects to GHG emissions abatement will therefore be greater than what will be credited to them. On the other hand, permanent GHG emissions that may result as a consequence of the implementation of sink project activities are treated as non-permanent. If these emissions are above avoided baseline emissions, CDM-sinks will result in net increases of GHG emissions into the atmosphere. After briefly reassessing the non-permanence problem, this article explains how tCERs and lCERs should be quantified according to Decision 19/CP.9 of CoP-9 and how calculations are implemented in the forthcoming software CO<sub>2</sub> Land. Using a simple numerical example, it illustrates how the GHG accounting rule adopted at CoP-9 may result in net increases of GHG emissions. In the conclusion, a possible solution to this problem is proposed.
