The calculation of methane emissions from enteric fermentation can be performed according to three different levels of complexity (Tiers), see [IPCC(2006)](https://git-dmz.thuenen.de/vos/EmissionsAgriculture2023/-/wikis/9%20Literature#ipcc-intergovernmental-panel-on-climate-change-2006)-10.24 ff. For details of the procedures applied see the respective animal category chapters. The choice of the complexity level depends on whether the animal category under consideration is considered a key source with respect to methane emissions from enteric fermentation. If this is the case, a Tier 2 or Tier 3 method has to be used.
The calculation of methane emissions from enteric fermentation can be performed according to three different levels of complexity (Tiers), see [IPCC(2006)](https://git-dmz.thuenen.de/vos/EmissionsAgriculture2023/-/wikis/9%20Literature#ipcc-intergovernmental-panel-on-climate-change-2006)-10.24 ff. For details of the procedures applied see the respective animal category chapters. The choice of the complexity level depends on whether the animal category under consideration is considered a key source with respect to methane emissions from enteric fermentation. If this is the case, a Tier 2 or Tier 3 method has to be used.