[A-CG46] 陸域生態系の物質循環

[ACG46-03] Revisiting livestock greenhouse gas emissions in the Eurasian Drylands

*Banzragch Nandintsetseg¹、Kaiwen Guo²、Yasunori Kurosaki¹、Jinfeng Chang² (1.Tottori Univ., International Platform for Dryland Research and Education、2.Zhejiang Univ., College of Environmental and Resource Sciences, China)

キーワード：Greenhouse gas emissions, Livestock emissions, Eurasian drylands, Methane

Anthropogenic climate change poses a global challenge, with livestock systems accounting for 19.2–30.3% of global greenhouse gas (GHG) emissions, primarily methane (CH₄) and nitrous oxide (N₂O). In the Eurasian Drylands (EAD), livestock production is essential to local economies and livelihoods, particularly in vulnerable areas. Meanwhile, livestock is also a significant contributor to national GHG emissions in most EAD countries, necessitating urgent mitigation efforts. Therefore, assessing the magnitude and intensity of livestock GHG emissions in the EAD using refined and adaptive approaches is essential for effective climate strategies. This study applies the modified IPCC Tier 2 approach to assess long-term (1961–2023) livestock GHG emission patterns in six EAD countries—Mongolia, Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan—focusing on enteric fermentation and manure management. During 1961–2023, livestock numbers increased significantly, particularly after 1990 due to socioeconomic changes, with the highest populations in Uzbekistan, Mongolia, and Kazakhstan. Concurrently, livestock GHG emissions grew 1.6-fold, increasing by 60.1% since 1990 to reach 118.4 million tons (Mt) CO₂-equivalent (CO₂eq) in 2023 (CH₄: 94.2 Mt and N₂O: 24.2 Mt). By 2023, the top three GHG-emitting countries in the EAD were Uzbekistan (41.3 Mt CO₂eq), Mongolia (26.3 Mt CO₂eq), and Kazakhstan (22.7 Mt CO₂eq). Enteric fermentation was the largest CH₄ source, contributing 97%, while N₂O emissions were mainly from manure management. Compared to the UNFCCC inventories, which primarily use the Tier 1 method, our Tier 2-based estimates of livestock GHG emissions were higher. This difference stems from Tier 2 accounts for productivity variations (meat and milk) for gross energy calculations. Despite lower reported livestock emissions, the livestock sector remained the largest emitter in Mongolia (30.4% of total emissions) and a significant contributor in Uzbekistan (11%). These findings highlight the critical role of livestock in EAD GHG emissions, emphasizing the urgency for targeted mitigation strategies.
*These authors contributed equally