Implications of sustainable development considerations for comparability across nationally determined contributions

An important component of the Paris Agreement is the assessment of comparability across nationally determined contributions (NDCs). Indeed, game-theory literature on international environmental agreements highlights the need for comparable emission-mitigation efforts by countries to avoid free-riding 1 . At the same time, there are well-recognized links between mitigation and other national priorities, including but not limited to the 17 United Nations Sustainable Development Goals (SDGs)2–6, which raises the question of how such links might influence comparability assessments. Here, using a global integrated assessment model 7 , we demonstrate that geographical distributions of the influence of meeting the domestic mitigation component of the NDCs on a subset of the broader SDGs may not align with distributions of effort across NDCs obtained from conventional emissions-based or cost-based comparability metrics8–11. This implies that comparability assessments would be altered if interactions between mitigation and other SDGs were accounted for. Furthermore, we demonstrate that the extent to which these distributions differ depends on the degree to which mitigation activities directly affect broader SDGs domestically and indirectly affect international goals, and whether these effects are synergistic or antagonistic. Our analysis provides a foundation for assessing how comparability across NDCs could be better understood in the larger context of sustainability.