Analysing the international spillovers of climate change mitigation policies

This paper presents a methodological framework to analyse international spillovers from domestic climate mitigation policies - specifically economic, technology, and policy spillovers - and their impacts on global emissions and economic outcomes. These effects can be positive - such as accelerating low-carbon technology diffusion or the implementation of mitigation policy adoption abroad - or negative - such as shifting emissions across countries, i.e., carbon leakage, and fragmenting international markets. Advancing a shared understanding of international spillovers is essential to the IFCMA’s objective of enhancing the global effectiveness of mitigation efforts. To this end, the report provides a typology of spillover effects and transmission channels, reviews tools available to analyse them, synthesises the existing evidence, and explores policy design and responses to manage spillovers. This framework forms the analytical foundation for the upcoming IFCMA work to deepen the evidence base and support more co-ordinated international climate action.