Enteric methane emission estimates for cattle in Ethiopia from 1994 to 2018

The objective of this study was to estimate enteric methane emissions of the Ethiopian cattle population using the Intergovernmental Panel on Climate Change (IPCC) Tier 2 approach. A comprehensive literature review was undertaken to obtain country-specific livestock activity data required to estimate emission factors using the Tier 2 method. Indigenous multi-purpose breeds in the mixed crop-livestock and pastoral/agro-pastoral production systems represent more than 96-97% of the cattle population, and the remainder are specialized dairy breeds. Mean enteric emissions factors from 1994 to 2018 for cattle sub-categories ranged from 3.4 kg to 74 kg methane/head/year for calves older than six months and adult cows in production systems, and from 5.2 kg to 57 kg methane/head/year and 6 kg to 64 methane/head/year for calves less than six months and adult cows in the mixed crop-livestock and pastoral/agro-pastoral production systems,. The national average emission factor for dairy and multi-purpose cows was 74 kg methane/head/year- and 60 kg methane/head/year, across the time series. The current study is the first of its kind for Ethiopia, relying on country-specific animal performance data. It is expected to contribute to an improved national greenhouse gas inventory and provide a basis for better quantification of mitigation targets. Uncertainty of enteric methane emission estimates could be further reduced in the future with more complete data on cattle populations, animal performance and feed characterization.