Greenhouse gas emissions in US beef production can be reduced by up to 30% with the adoption of selected mitigation measures

The United States is the world's largest beef producer and fourth largest exporter, processing approximately 33 million head of cattle annually to produce over 12.3 million tonnes of beef. While a crucial food source and significant employer, this industry generates 201 Mt of greenhouse gas (GHG) emissions yearly—3.3% of total US emissions. Despite efficiency gains over the past 50 years and a growing commitment from industry actors to reduce GHG emissions, identifying optimal intervention strategies remains a challenge. This is partly because emissions vary spatially and by production context, making it difficult to determine where mitigation efforts will be most effective. The US beef supply chain is exceptionally complex, lacking transparency that hinders effective GHG emission reduction. The movement of cattle and feed isn't currently traceable, necessitating models to estimate subnational commodity flows and regional impacts. Existing life cycle assessment (LCA) models aggregate impacts by commodity categories, failing to connect subnational flows to spatially explicit environmental impacts. This limits their ability to assess the reduction potential of regionally specific practices and the spatially variable impacts in downstream supply chain stages. This research addresses this gap by providing a spatially explicit, fine-scale ‘cradle-to-gate’ assessment of GHG impacts and mitigation opportunities in the US beef supply chain. The study aims to identify emission hotspots, quantify individual and combined reduction potentials from applying different interventions across locations and supply chain stages, and ultimately inform decision-making for prioritizing emission mitigation strategies. The study acknowledges that its results represent a high-end estimate under ubiquitous adoption assumptions, with other feasibility constraints requiring further research. The selected mitigation strategies include those that directly reduce emission sources and those that increase carbon sequestration potential of working lands; it is not an exhaustive list but rather a selection of promising opportunities.

Existing literature highlights the significant environmental footprint of beef production, particularly concerning GHG emissions. Studies such as Rotz et al. (2019) have quantified the environmental footprints of beef cattle production in the US, providing baseline emission data. However, these studies often lack the spatial resolution needed to pinpoint effective mitigation strategies. Other research (e.g., Herrero et al., 2015; Poore & Nemecek, 2018) emphasizes the need for more precise assessments to guide targeted interventions. The complexity of the US beef supply chain, highlighted by studies like Suszkiw (2019) and Drouillard (2018), underscores the challenges of tracking commodity flows and their environmental consequences. The lack of transparency, discussed by O’Rourke (2014) and Castonguay et al. (2023), prevents effective targeting of emission reduction efforts. Previous LCA models often aggregate impacts, neglecting the regional variations in emission intensities and the potential for regionally specific mitigation strategies. This study builds upon this existing literature by incorporating spatially explicit data and a comprehensive supply chain model to overcome these limitations. The research acknowledges and incorporates findings from prior studies on enteric methane mitigation (Beauchemin et al., 2022) and adoption of conservation practices (Ranjan et al., 2019; Prokopy et al., 2019) to provide a more comprehensive and contextually relevant assessment.

This study utilizes a spatially explicit, fine-scale ‘cradle-to-gate’ life cycle assessment (LCA) to quantify GHG emissions and mitigation opportunities within the US beef supply chain. The methodology integrates a spatially determined impact assessment of production across the entire supply chain with a transport cost-minimization model. This model connects subnational agricultural commodity flows (feed and cattle) and individual beef processing facility demand. This approach bridges a critical information gap, enabling prioritization of emission mitigation strategies. The model considers various stages: crop production (corn, soybeans, alfalfa, etc.), grazing, intermediate feed processing, feedlots, dairy cattle production, and beef processing. Spatially explicit parameters include yields, land use change, and US averages for other inputs and outputs. The supply chain model employs linear programming to minimize total impedance, considering county- and facility-scale feed and animal supplies and demands. The USDA 2017 census provided data on livestock supplies and demands at the county level, scaled to total commercially slaughtered beef quantities. Baseline GHG emissions were estimated for each stage, incorporating data from the US EPA and other sources. County-level average GHG estimates of feed ingredients were updated to account for carbon sequestration from conservation practices. Emissions from on-farm livestock production (enteric fermentation, manure management, energy use) were estimated, considering regional differences in diets, operations, and growth phases. Processing stage emissions included fuel/electricity use (from eGRID data), and embedded emissions from upstream cattle production. The model also incorporated the proportion of different cattle types supplied to each processing facility. The study then examined various GHG mitigation opportunities across supply chain stages, considering the existing adoption of conservation management strategies (e.g., cover cropping, nutrient management). Where COMET-PLANNER estimates differed significantly from other literature, the more conservative estimate was used. The analysis involved 42 mitigation strategies categorized by supply chain stages and considered a variety of practices including cover crops, conservation tillage, nutrient management, irrigation improvements, telemetrics, land use change moratoria, prescribed grazing, riparian restoration, rangeland planting, silvopasture, adaptive multi-paddock grazing, feed additives, manure management, and energy management in processing. The results present a high-end estimate of mitigation potential, assuming widespread adoption and overcoming feasibility constraints.

The study found that the US beef industry emits 257.5 Mt CO₂e yr⁻¹ (Fig. 2), with 15% from feed production, 64% from grazing, 19% from confinement, and 3% from processing. Fed beef, culled beef, and culled dairy cows have average emission intensities of 32.6 kgCO₂e kg⁻¹, 30.0 kgCO₂e kg⁻¹, and 14.5 kgCO₂e kg⁻¹ boneless beef, respectively. Emissions from feed production and confinement are concentrated in the Great Plains and Midwest, while grazing emissions are more evenly distributed across the western US (Fig. 3). The model demonstrates that up to 30% of baseline GHG emissions could be mitigated through the implementation of various alternative practices (Tables 1, 3). This represents 20 Mt CO₂e reduced and 58 Mt CO₂ sequestered annually. The majority (19%) of the mitigation potential is in the grazing stage, primarily through short-term carbon sequestration (Fig. 2). Feed production mitigation could reduce emissions by 54% (20.6 Mt CO₂e), while feedlot emissions could be reduced by 12% (4.7 Mt CO₂e) using feed additives (Fig. 4). Dairy production interventions could reduce emissions by 42% (3.5 Mt CO₂e), and processing stage emissions could be lowered by 26% (1.8 Mt CO₂e) through energy management. Silvopasture, applied across eligible grazing land, reduces cradle-to-gate emissions by 13% via carbon sequestration. Mitigation opportunities are unevenly distributed geographically, with hotspots in the Northern Great Plains and Southeast (Figs. 5, 6). These regions offer significant potential for carbon sequestration through practices like silvopasture and wetland restoration. Hotspots for feed production mitigation coincide with concentrate feed sourcing regions. Increasing cover crop adoption, nutrient management, and farm energy efficiency can significantly reduce emissions (Fig. 6). Reducing land use change for feed production is also highlighted as a crucial mitigation strategy.

The findings demonstrate a substantial potential for GHG emission reduction in the US beef industry, emphasizing the importance of spatially explicit LCA modeling for identifying key leverage points across regions and supply chain stages. While the study provides a theoretical upper-bound estimate of mitigation potential, the identification of specific hotspots for mitigation strategies in different regions and supply chain stages provides valuable insights for targeted interventions. The significant potential for carbon sequestration through practices like silvopasture and riparian restoration highlights the role of land-based strategies in addition to direct emission reduction measures. The unequal spatial distribution of mitigation opportunities underscores the need for regionally tailored strategies. While the study acknowledges the existence of economic and socio-cultural constraints on the adoption of these practices, the high-end estimate highlights the transformative potential of these strategies under favorable conditions. Future research should investigate the economic and social feasibility of implementation, considering potential trade-offs with other environmental, social, and economic outcomes. The methodological approach of this study serves as a valuable model for other agricultural sectors and countries aiming to effectively address climate change and achieve climate commitments.

This study demonstrates the significant potential for mitigating greenhouse gas emissions in the US beef industry, estimating a 30% reduction achievable through a combination of emission reduction and carbon sequestration strategies. Spatially explicit analysis reveals hotspots for mitigation, highlighting opportunities for targeted interventions. The research emphasizes the importance of integrating land-based carbon sequestration strategies alongside direct emission reduction measures. While implementation faces challenges, the findings provide a roadmap for the industry, policymakers, and stakeholders to prioritize mitigation efforts and achieve climate goals. Future research should focus on evaluating the economic and social feasibility of the identified strategies, along with exploring additional mitigation opportunities and incorporating more refined emission metrics.

The study's results represent a high-end theoretical potential for mitigation, based on assumptions of ubiquitous adoption of various practices and overcoming economic, social, or other feasibility constraints. Actual adoption rates may be lower due to various factors. The selection of mitigation strategies was not exhaustive, and other important opportunities, such as changes in feed diets and selective breeding, were not included in the analysis. The study primarily used data from 2017, and more recent data could provide a more current and accurate assessment. The spatial resolution of the data used may affect the precision of the results. Finally, uncertainties and data limitations, particularly regarding long-term carbon sequestration rates, can impact the overall accuracy of the estimates.