Strategies for mitigating greenhouse gas emissions from US dairy farms toward a net zero goal

Authors: Rotz, Clarence; BRIGGS, KAITLYN - Consultant; HRISTOV, ALEXANDER - Pennsylvania State University; Leytem, April; Young, Eric; HAGEVOORT, ROBERT - New Mexico State University; MULLINAX, DENISE - California Dairy Research Foundation

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2025
Publication Date: 7/8/2025
Citation: Rotz, C.A., Briggs, K., Hristov, A., Leytem, A.B., Young, E.O., Hagevoort, R., Mullinax, D. 2025. Strategies for mitigating greenhouse gas emissions from US dairy farms toward a net zero goal. Journal of Dairy Science. 26392. https://doi.org/10.3168/jds.2025-26392.
DOI: https://doi.org/10.3168/jds.2025-26392

Interpretive Summary: To counter the threat of global warming and related changes in climate, the US dairy industry, along with many industries relying on dairy products, has set a goal for net zero greenhouse gas (GHG) emissions or GHG neutrality. Because most of the emissions for the dairy industry are associated with milk production, mitigation must begin at the farm. Up to 24 mitigation strategies were assessed individually and in combination for use on farms in the major dairy regions of the US. Considering plausible scenarios, GHG emission reductions with individual mitigation strategies ranged from 0.3 to 20% and practical combinations reduced emissions over all farms by 46%. With less plausible, more extreme assumptions on mitigation potentials, GHG emissions could be reduced by up to 70%. Thus, mitigation strategies have the potential for providing large reductions in GHG emissions from dairy farms, but achieving long-term GHG neutrality over all US dairy farms appears improbable.

Technical Abstract: The US dairy industry has set the goal of attaining greenhouse gas (GHG) neutrality by mid-century. Reaching this goal requires the implementation of multiple strategies for mitigating and offsetting GHG emissions. A large range of animal feeding, manure handling, cropping and energy saving strategies were evaluated alone and in combination to quantify their potential for reducing the farmgate life cycle carbon (C) footprint of milk production. Representative dairy farms in Pennsylvania, New York, Wisconsin, Idaho, California, Arizona and Texas were simulated without and with various mitigation strategies using the Integrated Farm System Model (IFSM). The benefit obtained was quantified as the change in milk C footprint with a given strategy or combination of strategies compared to that of the base farm. Assumptions were made for plausible and maximum possible reductions with the strategies. For plausible scenarios, milk C footprint reductions achieved with individual strategies ranged from 0.3 to 20%. Strategies with the largest benefit included anaerobic digestion of manure, a covered manure storage using a flare for methane destruction, an enclosed barn with destruction of the methane in exiting ventilation air, and the use of a feed additive for mitigating enteric methane. A combination of appropriate strategies provided an average reduction in the milk C footprint over all farms of 46%. Potential offsets that might be achieved on a few farms through soil carbon sequestration or use of food waste in anaerobic digestion provided additional reductions of 7 and 4.9%, respectively. With the use of less probable maximum mitigation strategies, individual reductions in GHG emissions ranged from 0.3 to 32% with a combination of appropriate strategies averaging 70% over all farms. Considering alternative metrics for quantifying the global warming effects of methane as a short-lived gas in the atmosphere provided a possible short-term solution for demonstrating climate neutrality of US dairy farms. If implementation of mitigation strategies over the next several years could reduce total methane emissions from all farms at a rate greater than 1% per year, metrics such as GWP* would predict no effect on global temperature. Following life cycle assessment procedures, mitigation strategies have the potential for providing large reductions in GHG emissions but achieving long-term GHG neutrality over all US dairy farms appears improbable.