ABSTRACT
This chapter presents the unit of measurement for carbon accounting, the tonne of CCX-equivalent. It examines two particular cases: accounting of use, storage or destruction of biomass, and second, radiative forcing in the aviation sector. The chapter introduces the basic rules and principles of carbon accounting. Carbon accounting makes a distinction between fossil carbon and carbon from living matter. The boundaries of greenhouse gas (GHG) emissions accounting and reporting should be defined appropriately. Boundaries are chosen on the basis of the entity under study, the reason for gathering information on GHGs and users' needs. Given the significant number of sources of GHG emissions and their very low concentration in the atmosphere, it is rarely possible to measure GHG emissions resulting directly from a particular action. The revision of global warming potentials can be mostly explained by two main factors: change to the inclusion and strength of indirect effects, and changes in concentration of other GHGs.
