This paper addresses the challenge of developing a ‘bottom-up’ marginal abatement cost curve (MACC) for greenhouse gas emissions from UK agriculture. A MACC illustrates the costs of specific crop, soil, and livestock abatement measures against a ‘‘business as usual’’ scenario. The results indicate that in 2022 under a specific policy scenario, around 5.38 MtCO2 equivalent (e) could be abated at negative or zero cost. A further 17% of agricultural GHG emissions (7.85 MtCO2e) could be abated at a lower unit cost than the UK Government’s 2022 shadow price of carbon (£34 (tCO2e)-1). The paper discusses a range of methodological hurdles that complicate cost-effectiveness appraisal of abatement in agriculture relative to other sectors.