Decarbonizing Urban Heating Systems in Europe: Navigating Governance Challenges in Seven Pioneering Cities

City governments' transformative capacity in climate mitigation has been attracting increasing attention in academia and practice, but until recently the decarbonization of the heating sector has tended to be neglected in debates on urban energy and climate policy. Moreover, the literature on the transformation of heating systems has primarily focused on techno-economic dimensions, largely overlooking spatial complexities and urban government capacities. Aiming to fill this gap, this study maps the emerging governance challenges faced by seven European cities that are pioneering heating transformation in their respective countries. Based on document analyses, expert interviews (N = 55), participant observation, and written feedback from key representatives of municipal governments, we identify significant governance challenges and explore how cities navigate them, applying a conceptual framework of urban government capacities. The analysis emphasizes the complexity of urban heating transformations, reflecting critically on broader debates on city governments' capacity to transform infrastructure. Results reveal that the city governments are navigating short- and long-term visions, responding to urgency and regulatory uncertainties by opting for incremental planning. Their urban transformation pathways are shaped by the interplay of existing infrastructures, tight timeframes, and regulatory gaps, often resulting in reliance on incremental experimentation, missed energy-saving opportunities, and difficulty in developing viable business cases for net-zero district heating systems.