Ecosystems Services and Management Program, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria.
Proc Natl Acad Sci U S A. 2014 Mar 11;111(10):3709-14. doi: 10.1073/pnas.1308044111. Epub 2014 Feb 24.
Livestock are responsible for 12% of anthropogenic greenhouse gas emissions. Sustainable intensification of livestock production systems might become a key climate mitigation technology. However, livestock production systems vary substantially, making the implementation of climate mitigation policies a formidable challenge. Here, we provide results from an economic model using a detailed and high-resolution representation of livestock production systems. We project that by 2030 autonomous transitions toward more efficient systems would decrease emissions by 736 million metric tons of carbon dioxide equivalent per year (MtCO2e⋅y(-1)), mainly through avoided emissions from the conversion of 162 Mha of natural land. A moderate mitigation policy targeting emissions from both the agricultural and land-use change sectors with a carbon price of US$10 per tCO2e could lead to an abatement of 3,223 MtCO2e⋅y(-1). Livestock system transitions would contribute 21% of the total abatement, intra- and interregional relocation of livestock production another 40%, and all other mechanisms would add 39%. A comparable abatement of 3,068 MtCO2e⋅y(-1) could be achieved also with a policy targeting only emissions from land-use change. Stringent climate policies might lead to reductions in food availability of up to 200 kcal per capita per day globally. We find that mitigation policies targeting emissions from land-use change are 5 to 10 times more efficient--measured in "total abatement calorie cost"--than policies targeting emissions from livestock only. Thus, fostering transitions toward more productive livestock production systems in combination with climate policies targeting the land-use change appears to be the most efficient lever to deliver desirable climate and food availability outcomes.
牲畜温室气体排放量占人为排放量的 12%。可持续集约化牲畜生产系统可能成为关键的气候缓解技术。然而，牲畜生产系统差异很大，使得实施气候缓解政策成为一项艰巨的挑战。在这里，我们提供了一个经济模型的结果，该模型使用了详细和高分辨率的牲畜生产系统表示。我们预计，到 2030 年，自主向更高效系统的过渡每年将减少 7.36 亿吨二氧化碳当量的排放（MtCO2e⋅y(-1)），主要是通过避免 1.62 亿公顷自然土地转化所产生的排放。一个针对农业和土地利用变化部门排放的适度缓解政策，其碳价格为 10 美元/吨二氧化碳当量（US$10/tCO2e），可能会减少 3223 MtCO2e⋅y(-1)的排放。牲畜系统的转变将贡献总减排量的 21%，牲畜生产的区域内和区域间重新安置将贡献 40%，而所有其他机制将增加 39%。如果政策只针对土地利用变化的排放，也可以实现 3068 MtCO2e⋅y(-1)的减排量。严格的气候政策可能导致全球每人每天的食物供应量减少多达 200 卡路里。我们发现，针对土地利用变化排放的缓解政策比仅针对牲畜排放的政策效率高 5 到 10 倍——以“总减排卡路里成本”来衡量。因此，促进向更高效的牲畜生产系统转变，并结合针对土地利用变化的气候政策，似乎是实现理想的气候和食物供应结果的最有效手段。
