Nature-based solutions for urban sustainability

Cities 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and duration of unprecedented climate-related events, threats to biodiversity, and the concentration of people and outdated infrastructure in cities demand new strategies to ensure that cities are livable, resilient, and equitable.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).