Carbon sequestration projects in the context of the Clean Development Mechanism (CDM) suffer from the stigma of permanence risk. The risk that carbon reduced or sequestered in forestry projects is release further down the road is in fact undeniable, whoever bears the onus. The merit of the so-called "ton/year approach" is to destroy the fiction of infinity when talking about permanent sequestration. The merit of the "Columbian proposal" is to destroy the fiction of comparability between technological emission reduction and sequestration in natural systems. Yet, both approaches are discussed as more or less unrelated alternatives. By making use of both methodologies and providing a link between both proposals on permanence in CDM forestry, the present article puts forward the proposal of leasing reduction certificates.