Who governs climate adaptation? Getting green roofs for stormwater retention off the ground

Green roofs are an innovative solution for urban stormwater management. This paper examines governance arrangements for green roofs as a no-regrets' climate adaptation measure in five cities. We analysed who governs green roofs, why and with what outcome. Our results show that hierarchical and market arrangements co-exist in the various stages of the policy process. Cities with a higher prevalence of hierarchical arrangements have substantially higher implementation rates for green roofs. Although private sector involvement is crucial for raising efficiencies, a significant level of public responsibility taken by local governments appears to be salient for unleashing the potential of green roofs.