2.2. Concept of carbon categorization
This study follows the CBM concept which has already been applied to the works of Patthanaissaranukool et al. (2013) and Polprasert et al. (2015). With its concept, not all C emitted to the
atmosphere is considered to cause harmful effects of global warming. It is because a certain amount of C needs to be circulated between earth's atmosphere and lithosphere so as to sustain lives living in the biosphere. Therefore, C in the CBM is classified based on movement pathway and usefulness into three groups-emission, fixation, and reduction.