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 CO 2 e/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.

中文翻译：

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替代牛肉生产系统对气候的影响取决于所使用的功能单位：重量或货币价值


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。美国和加拿大约占世界牛肉供应量的四分之一。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几乎翻了四倍，从 10.2 到 37.6，平均21.4千克二氧化碳2 e/kg 胴体重量 (CW)。考虑土壤碳封存 (C-seq) 的研究报告显示，温室气体排放的缓解潜力最高 (80%)，其次是生长促进技术 (16%)、饮食调整 (6%) 和放牧管理改进 (7%)。我们的研究强调了使用每项经济活动的碳强度（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（每公斤水的温室气体排放量）进行比较的影响，以比较不同的肉牛产品。虽然草原上的寿命比例与传统的基于体重的指标之间存在正相关关系，但发现草成品牛肉的每项经济活动的碳强度低于饲养场成品牛肉。我们的研究强调需要将土地利用和管理影响以及土壤 C-seq 纳入牛肉温室气体排放和缓解评估的基本方面。