Greenhouse gas accounting in urban digital twins

Abstract As current efforts remain insufficient to limit global warming to 1.5 °C, increasing expectations are placed on emerging technologies such as urban and national digital twins (DTs). Their number and spatial coverage are rapidly expanding, alongside a growing diversity of exploratory use cases. While the literature highlights their potential across multiple domains, a knowledge gap persists regarding their methodological application to subnational spatial greenhouse gas accounting, a key evidence base for local climate action. This study applies a multi-method approach to examine how frontrunner cities utilise DTs in greenhouse gas inventories and to assess their potential for spatial subnational greenhouse gas accounting. Interview findings indicate that greenhouse gas inventories and urban DT initiatives are largely pursued as disconnected efforts within cities. Five case studies demonstrate significant untapped potential beyond current inventory practices. DTs can help address limitations and biases in existing approaches by providing complementary insights into local emission patterns across regions, cities, and rural municipalities. Realising this potential requires systematic metadata attribution to distinguish between various emissions allocation principles, enabling georeferenced, disaggregated calculations and spatiotemporal representation of results. These methodological advances substantially enhance the interpretability, transparency, and policy relevance of subnational greenhouse gas inventories.