This dataset contains agricultural greenhouse gas emission estimates and projections for Northern Ireland from 2020-2027 reported under multiple emission metrics. Past emissions are taken from the The UK National Atmospheric Emissions Inventory (NAEI). Projections are based on Department of Agriculture, Environment and Rural Affairs (DAERA, Northern Ireland) analysis to support the draft Climate Action Plan 2023-2027. These were calculated by DAERA following assumptions of mitigation efficiency and rollout potential, covering 4 scenarios from most to least conservative: headwinds, central, tailwinds and tailwinds + additional adoption of emission suppressing feed additives. Gases are reported in quantities of methane, nitrous oxide and carbon dioxide, then aggregated under a range of 'carbon dioxide equivalent' reporting metric approaches (the 100-year Global Warming Potential, the 20-year Global Warming Potential, the 100-year Global Temperature change Potential and two applications of 'GWP*') based on standard practice and recent carbon reporting literature to illustrate different ways of weighting gases and inferring mitigation value. The weighting factors and calculations used to report emissions under these multiple metrics are supplied in an accompanying xlsx calculator tool. The work was supported by the Natural Environment Research Council (NE/W004976/1). Full details about this dataset can be found at https://doi.org/10.5285/425ba61b-0dbf-4e51-8158-f226ad1427cb