In recent years, Nature-based Solutions (NbS) gained momentum in the debates over urban sustainability following the acknowledgement of the wide range of benefits they can produce in enhancing environmental conditions and human well-being. For example, positive effects associated with NbS deployment have been observed in terms of improved urban biodiversity (Xie and Bulkeley, 2020), disaster risk reduction (Ruangpan et al., 2020), diminished stress and anxiety (Vujcic et al., 2017), better air quality (Marando et al., 2016) etc. Therefore, both the literature (see, e.g., Cohen-Schacham et al., 2019, Raymond et al., 2017) and international institutions (CBD, 2022, EC, 2021) stress the importance of NbS implementation in cities to advance sustainability transformation.
However, a number of elements hinder the implementation of urban NbS. The complexity inherent in planning and the coexistence of several priorities at the city level add to the technical and economic aspects present in any urban context. This calls for an assessment of NbS feasibility that includes different research angles. More specifically, to understand what needs to be done to enable wider NbS implementation and thus accelerate urban transformations, their social, political, and legal feasibility must be considered (Patterson et al., 2021).
Researchers in Transformative Cities WP4 reviewed the main policy-related and legal barriers to NbS implementation reported by the NbS literature. Using a legal lens, this analysis allowed us to group the identified barriers into three categories, namely, institutional, procedural, and substantive. Institutional barriers arise when how authorities are organised or powers are distributed among them hinders NbS implementation. An example is the limited power of local governments to steer land use planning due to an unclear allocation of responsibilities (e.g., Raška et al., 2022). Procedural barriers refer to provisions (or the lack thereof) regulating procedural rights and their effects. For instance, the lack of mechanisms ensuring public participation in planning can inhibit the uptake of NbS in favour of grey infrastructure (e.g., Wamsler et al., 2020). Finally, substantive barriers stem from provisions (or the lack thereof) establishing rights or obligations in particular circumstances. For example, property rights may create a mismatch between private and public interest and slow down NbS implementation when the land needed for NbS is privately owned (Hartmann, Slavíková and McCarthy, 2019).
These results show how accelerating urban sustainability transformations through the implementation of NbS requires, among others, coherent and transparent governance mechanisms, and the capability to establish trade-offs when distinct interests are at stake. These findings, combined with the current governance frameworks present in some of the Transformative Cities case studies areas, will inform the next phases of WP4 and WP5 activities in the attempt to develop potential scenarios able to unlock sustainable urban futures.
CBD (2022) ‘Kunming-Montreal Global biodiversity framework’ CBD/COP/15/L.25.
Cohen-Shacham, E. et al. (2019) ‘Core principles for successfully implementing and upscaling Nature-based Solutions’, Environmental Science and Policy. Elsevier, 98(June 2018), pp. 20–29. doi: 10.1016/j.envsci.2019.04.014.
European Commission (2021) Forging a climate-resilient Europe: the new EU Strategy on Adaptation to Climate Change. COM (2021) 82 final.
Hartmann, T., Slavíková, L. and McCarthy, S. (2019) ‘Nature-Based Solutions in Flood Risk Management’, in Nature-Based Flood Risk Management on Private Land. Cham: Springer International Publishing, pp. 3–8. doi: 10.1007/978-3-030-23842-1_1.
Marando, F. et al. (2016) ‘Removal of PM10 by Forests as a Nature-Based Solution for Air Quality Improvement in the Metropolitan City of Rome’, Forests, 7(12), p. 150. doi: 10.3390/f7070150.
Patterson, J. et al. (2021) ‘Finding feasible action towards urban transformations’, npj Urban Sustainability. Springer US, 1(1), pp. 1–8. doi: 10.1038/s42949-021-00029-7.
Raška, P. et al. (2022) ‘Identifying barriers for nature-based solutions in flood risk management: An interdisciplinary overview using expert community approach’, Journal of Environmental Management, 310(January). doi: 10.1016/j.jenvman.2022.114725.
Raymond, C. M. et al. (2017) ‘A framework for assessing and implementing the co-benefits of nature-based solutions in urban areas’, Environmental Science & Policy, 77, pp. 15–24. doi: 10.1016/j.envsci.2017.07.008.
Ruangpan, L. et al. (2020) ‘Nature-based solutions for hydro-meteorological risk reduction: a state-of-the-art review of the research area’, Natural Hazards and Earth System Sciences, 20(1), pp. 243–270. doi: 10.5194/nhess-20-243-2020.
Vujcic, M. et al. (2017) ‘Nature based solution for improving mental health and well-being in urban areas’, Environmental Research, 158, pp. 385–392. doi: 10.1016/j.envres.2017.06.030.
Wamsler, C. et al. (2020) ‘Environmental and climate policy integration: Targeted strategies for overcoming barriers to nature-based solutions and climate change adaptation’, Journal of Cleaner Production, 247, p. 119154. doi: 10.1016/j.jclepro.2019.119154.
Xie, L. and Bulkeley, H. (2020) ‘Nature-based solutions for urban biodiversity governance’, Environmental Science & Policy, 110, pp. 77–87. doi: 10.1016/j.envsci.2020.04.002.