Ness School of Management & Economics, South Dakota State University, Brookings, SD 57007.
Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX 77843.
Proc Natl Acad Sci U S A. 2024 Jul 30;121(31):e2321245121. doi: 10.1073/pnas.2321245121. Epub 2024 Jul 15.
Beef production has been identified as a significant source of anthropogenic greenhouse gas (GHG) emissions in the agricultural sector. United States and Canada account for about a quarter of the world's beef supply. To compare the GHG emission contributions of alternative beef production systems, we conducted a meta-analysis of 32 studies that were conducted between 2001 and 2023. Results indicated that GHG emissions from beef production in North America varied almost fourfold from 10.2 to 37.6 with an average of 21.4 kg COe/kg carcass weight (CW). Studies that considered soil C sequestration (C-seq) reported the highest mitigation potential in GHG emissions (80%), followed by growth enhancement technology (16%), diet modification (6%), and grazing management improvement (7%). Our study highlights the implications of using carbon intensity per economic activity (i.e., GHG emissions per monetary unit), compared to the more common metric of intensity on per weight of product basis (GHG emissions per kg CW) for comparisons across differentiated beef cattle products. While a positive association was found between the proportion of lifespan on grassland and the conventional weight-based indicator, grass-finished beef was found to have lower carbon intensity per economic activity than feedlot-finished beef. Our study emphasizes the need to incorporate land use and management effects and soil C-seq as fundamental aspects of beef GHG emissions and mitigation assessments.
牛肉生产已被确定为农业部门人为温室气体（GHG）排放的重要来源。美国和加拿大约占全球牛肉供应的四分之一。为了比较替代牛肉生产系统的温室气体排放贡献，我们对 2001 年至 2023 年间进行的 32 项研究进行了荟萃分析。结果表明，北美牛肉生产的温室气体排放量变化范围很大，从 10.2 到 37.6，平均值为 21.4 千克 COe/公斤胴体重量（CW）。考虑土壤碳固存（C-seq）的研究报告称，在温室气体减排方面具有最大的缓解潜力（80%），其次是生长增强技术（16%）、饮食修改（6%）和放牧管理改进（7%）。我们的研究强调了使用每经济活动的碳强度（即每货币单位的温室气体排放量）与更常见的基于产品重量的强度指标（每公斤 CW 的温室气体排放量）进行比较的意义，用于比较不同的牛肉产品。虽然发现寿命在草地上的比例与传统的基于重量的指标之间存在正相关关系，但发现草饲牛肉的经济活动碳强度低于饲养场饲养的牛肉。我们的研究强调需要将土地利用和管理效果以及土壤碳固存纳入牛肉温室气体排放和缓解评估的基本方面。
