2.2.3. Emission factors for methane from enteric fermentation
Tier 2 modelswere used to estimate the emission factors for dairy
and beef cows (see Penman et al., 2000).
We estimated the uncertainty in these emission factors bycalculatinghowthe uncertainty in
the variables used to calculate them propagated through the model.
We assumed that all of these variables were normally distributed.
Each is listed in Table 3 along with the source of the parameters for
the respective PDFs (see also Supplementary information).