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Feeding the world's population while minimising the contribution of agriculture to climate change is one of the greatest challenges facing modern society. This challenge is particularly pronounced for dairy production where the carbon footprint of products and the mitigation costs are high, relative to other food stuffs. This paper reviews a number of mitigation measures that may be adopted by dairy farmers to reduce greenhouse gas emissions from their farms. A simulation model is developed to assess the cost-benefit of a range of mitigation measures. The model is applied to data from Ireland, a country with a large export-oriented dairy industry, for a range of farms including top, middle and bottom performing farms from a profitability perspective. The mitigation measures modelled included animal productivity, grass production and utilisation, better reproductive performance, early compact calving, reduced crude protein, decreased fertiliser N, protected urea, white clover, slurry tank cover and low emission slurry spreading (LESS). The results show that over half of the greenhouse gas abatement potential and most of the ammonia abatement potential were realised with cost-beneficial measures. Animal and feed-related measures that increased efficiency drove the abatement of GHG emissions. Low-emission slurry spreading was beneficial for the bottom and middle one-third of farms, while protected urea and reducing nitrogen use accounted for most of the ammonia abatement potential for the most profitable farms. Results showed that combining mitigation measures resulted in a decrease of 23%, 19%, and 12% in GHG emissions below 2020 levels for the bottom, middle, and top performing dairy farms, respectively. The findings imply that top dairy farms, that are already managed efficiently and optimally, may struggle to achieve the national and international GHG reduction targets with existing technologies and practices. • The top dairy group may struggle to achieve the 2030 and future GHG reductions targets with existing technologies and practices • 56%–86% of emissions reduction achieved through mitigation measures that were cost effective, net-zero for all three groups • Farm-level MACCs can account for variability in GHG and NH3 mitigation potentials and costs, that are often missed at the sectoral or country level. • The study found that combining mitigation measures resulted in a decrease of 23%, 19%, and 12% in GHG emissions below 2020 levels for the bottom, middle, and top dairy groups, respectively • Farm-level marginal abatement cost curve (MACC) are useful for understanding the capacity to reduce gaseous emissions from specific agricultural systems or farms [ABSTRACT FROM AUTHOR]