Uncertainty estimates are an important component of a national inventory. Their purpose is to help improve the accuracy of inventories over time by helping to guide decisions on methodological choice and priorities for inventory improvement. Uncertainty estimates are not used to question the validity of emissions estimates in the national inventory. These assessments are made through the review of technical assessment process. Estimating and communicating uncertainty must be both practical and scientifically defensible. For example, a practical approach recognises that producing quantitative uncertainty estimates will rely upon statistically quantified uncertainties as well as expert judgment.
Identifying the sources of uncertainty is the first step in estimating uncertainty. These sources are typically disaggregated into uncertainties related to emissions and removals (e.g. initial biomass, growth, turnover, and decomposition rates) and uncertainties related to activity data (i.e. the area on which the emission has occurred). The INCAS framework has been designed to use the best available data for each input. Every effort has been made to reduce uncertainty for each input variable and modelling step through quality control and quality assurance processes.
Full details of the INCAS Uncertainty Analysis are available in the INCAS Standard Methods publication here.