Global climate action is not currently aligned with the Paris Agreement goals to limit temperature rise to “well below 2°C” over pre-industrial levels and to pursue efforts to limit it to 1.5°C. Societal well-being and economic stability continue to be highly dependent on climate-polluting inputs – especially fossil fuels for energy and nitrogen fertiliser for agriculture. The research project Society-wide Scenarios for Effective Climate Change Mitigation in Ireland (SSECCM) was a 1-year, preliminary desk study undertaken to inform the implementation of Irish policy on climate mitigation in the context of European Union (EU) and Paris Agreement objectives. It evaluated international studies of society-wide, long-term climate action scenarios, identifying their relevance to the specific situation in Ireland. Although carbon dioxide (CO2) remains the single most important greenhouse gas (GHG) to consider, emissions of methane (CH4) and nitrous oxide (N2O) also make a significant contribution to global climate disruption. The last two are especially important to Ireland because, although CO2 remains the dominant GHG, we have comparatively high emissions of these other GHGs, primarily from animal agriculture. A new open-source spreadsheet tool, “GHG-WE”, was developed for the project and has been released under an open licence. This tool incorporates GWP* (modified global warming potential), a metric recently developed to more accurately represent the combined climate effects of different GHGs.