Monitoring and verification of soil carbon changes under Article 3.4 of the Kyoto Protocol

Article 3.4 of the Kyoto Protocol allows forest management, cropland management, revegetation, and grazing land management to be treated as biospheric carbon sinks. Under conditions of strict verifiability, C sinks and sources must be monitored at the beginning and end of a commitment period. At its least stringent, verifiability would entail reporting of areas under a given practice and use of default values for a C stock change for each practice. A definition of verifiability between these extremes would allow simple methods to be applied for estimating changes in soil C.