Evaluation of innovative policy for nature-based solutions: analysis from three European city case studies

Abstract Addressing the current unprecedented climate and environmental challenges in our urban areas and beyond entails innovation in policymaking across sectors, rather than siloing, which has often been the status quo. Nature-based solutions (NBS) can provide tangible, innovative and integrated policy solutions to current challenges, including climate change and nature renewal, therefore departing from previous sustainable development approaches. At the same time, the policy integration NBS entail mean they are subject to complex governance influences. Through a comparative analysis of interview and policy workshop data in three European city case studies, this paper examines the external, societal and governing influences on NBS innovation, and the governance structures in which NBS innovation is likely to occur—including political aspects of NBS which have hitherto been relatively unexplored. The results indicate important facilitating and hindering factors across governing, societal and external categories, and show some association between NBS innovation and decentralized policy making. They highlight the importance of policy coherence of NBS initiatives with government policy/strategy; and of the willingness by policy makers/local government staff to engage with/appeal strategically to political decision-makers regarding external policy drivers—e.g. climate adaptation and health. The data also indicates that where citizen participation was built into NBS projects, this led to both innovation and additionality in design, quality, biodiversity, multi-functionality and co-benefits of green/blue spaces. Key differences that led to differing NBS outcomes included size and complexity of the urban area, and characteristics of the governing architecture.