Quantifying Greenhouse Gas Emissions and Carbon Footprint of Sheep Production Using the IPCC Tier 2 Approach

Livestock production significantly contributes to greenhouse gas (GHG) emissions, particularly methane (CH₄) and nitrous oxide (N₂O) originating from enteric fermentation and manure management. This study quantified the GHG emissions and cumulative carbon footprint of four commercial sheep farms (SF1, SF2, SF3, and SF4) in the Bursa region of Türkiye, with flock sizes of 200, 500, 150, and 800 adult Merino sheep (mature ewes and breeding rams), respectively. Using the IPCC Tier 2 methodology, the biogenic carbon footprint was estimated at 15.6 kg CO₂-eq per kg of boneless sheep meat. However, when indirect inputs were included, the cumulative carbon footprint reached 28.8 kg CO₂-eq for ewes and 32.3 kg CO₂-eq for breeding rams. These results indicate that indirect emissions from feed production account for the primary environmental load (49.8%), while on-farm energy-related emissions represent a minor portion (0.3%) of the total impact. The results demonstrate that while enteric fermentation (32.5%) remains a critical biological factor, the environmental burden of the feed supply chain is equally significant in intensive systems. These findings highlight that excluding indirect inputs leads to a substantial underestimation of the climate impact, suggesting that mitigation strategies must integrate nutritional optimization with enteric methane reduction to decarbonize sheep production effectively.