Adaptive Governance Through Urban Regulatory Sandboxes: Expert Perceptions from Four Spanish Climate-Neutral Cities

Cities face increasing pressure to accelerate climate action while operating within governance systems often characterised by institutional rigidity and slow regulatory adaptation. In this context, urban regulatory sandboxes have emerged as experimental instruments that enable municipalities to test innovative solutions while adapting institutional practices under conditions of uncertainty. Despite their growing implementation, limited evidence exists regarding their capacity to transform municipal governance itself. This research examines the conditions under which urban regulatory sandboxes can foster the governance capacities required for municipalities to lead the climate transition. A sequential mixed-methods design was applied, combining semi-structured interviews with municipal practitioners and a Likert-scale self-assessment instrument completed by the same practitioners. Four Spanish cities with active urban sandboxes—Barcelona, Madrid, Valencia, and Valladolid—were analysed across three governance dimensions: learning vs. isolation, flexibility vs. rigidity, and climate mission alignment. The findings suggest that, in the perception of the practitioners interviewed, urban sandboxes foster adaptive governance logics, though institutionalising these capacities exposes real tensions around intra- and inter-organisational collaboration, and the depth of transformation differs by each city context. These results carry practical implications for municipal policymakers seeking to integrate sandboxes as tools for climate-responsive urban governance and as enablers of local entrepreneurship and innovation ecosystems. This study contributes to the literature on adaptive governance and urban experimentation by positioning urban regulatory sandboxes as emerging instruments for leading climate transitions under conditions of uncertainty. Ultimately, urban sandboxes can serve as catalysts for embedding climate adaptability within municipal governance but only when accompanied by the deliberate institutional work needed to sustain them.