Nature-based solutions for urban sustainability

Abstract

Nature-based Solutions for Urban SustainabilityCities across the globe face growing sustainability and resilience challenges that will require innovative solutions and collaborative partnerships.The pace of climate change, the frequency and duration of unprecedented climate-related events, threats to biodiversity, and the concentration of people and outdated infrastructure in cities demand new strategies to ensure that cities are livable, resilient, and equitable.Nature-based solutions (NbS) are at the forefront of addressing impacts of climate change, especially in urban planning, practice, and research.A growing number of cities worldwide are exploring NbS, sometimes referred to as green infrastructure, urban nature, ecosystem-based adaptations, or simply environmental restoration or conservation ( 1 ).NbS incorporate natural processes to support adaptation to climate change and urbanization, as well as the restoration of ecological functions ( Fig. 1 ).While emphasized as a tool to address climate change in cities, NbS are also promoted for their benefits to individuals and communities, including improved public health, access to nature, and social equity ( 2 , 3 ).In contrast to traditional engineered urban infrastructure that is mostly rigid and inflexible over time, NbS provide flexibility to confront the shifting impacts of climate change and uncertainty of the future ( 4 , 5 ).In keeping pace with accelerating interest in urban NbS worldwide, key principles, frameworks, and classification schemes are emerging to understand and advance NbS ( 6 -11 ).Not only has there been an explosion of research on NbS in the last 10 years, there have also been new local, national, and international development directives supporting NbS implementation.For example, NbS have gained strong support in local climate adaptation plans ( 12 ) and national policy agendas within the United States, where the Biden Administration Executive Order 14072 ( 13 ) centered NbS for climate adaptation and mitigation alongside biodiversity protection.NbS are also emerging in international agendas through the European Union Horizon 2020 ( 14), International Union of Conservation of Nature ( 15 ), United Nations (UN) ( 16 ), Intergovernmental Panel on Climate Change ( 17 ), and the World Economic Forum ( 18 ).Despite rapid uptake in policy, uncertainties remain about scaling up and scaling out of NbS to address climate change in cities, particularly in diverse social-cultural, governance, ecological-biophysical, climatic, and infrastructural contexts ( 19 ).For example, while NbS are expected to be versatile, multifunctional, and help mitigate the impact of climate risks, the full suite of NbS benefits and potential tradeoffs is uncertain, particularly under changing climate and more severe extreme weather-related events ( 4 , 20 -22 ).The recent frameworks on urban NbS have largely emerged from the Global North, and the application of these frameworks in other contexts, such as in the Global South, informal urban settlements, or from Indigenous perspectives, is not always appropriate ( 23 -26 ).Moreover, in some global regions, such as Latin America and the Caribbean, urban NbS are predominantly seen (and reported upon) in the wealthiest or largest nations and cities; NbS are less systematically studied elsewhere in the Latin America region, despite likely broad implementation through bottom-up or un-funded initiatives ( 27 , 28 ).Continued efforts studying place-based design, implementation, and functioning of NbS across diverse global contexts will provide an important solution-set for addressing future urban sustainability and resilience challenges.The objective of this paper is to introduce a Special Feature: "Nature-based Solutions for Urban Sustainability"-a collection of four articles addressing the current state of global urban NbS science and conceptual framings.The special feature explores opportunities for research and practice to scale up NbS to address equity, justice, and inclusion while enabling transformation in urbanized areas.The special feature includes a review and three perspectives papers that leverage learnings from NATURA (NAT ure-based Solutions for U rban R esilience in the A nthropocene), an international network of networks that connects academic researchers and practitioners around the world and provides a critical platform for knowledge exchange.The works in the special feature build upon the progress made through global collaborations on urban NbS within NATURA.