There is a growing movement to value and incorporate urban ecosystem services in the planning and management of sustainable cities. There is evidence to support a role for urban nature and green infrastructure in improving air and water quality, reducing the urban heat island, mitigating storm surge and coastal flooding, sequestering carbon, and enhancing mental health, cultural and social services. However, there has been a lack of critical evaluation of the potential for urban nature to provide these services, especially in the context of the broader social and built systems that also affect the delivery of these benefits to urban residents. As a result, we know little about the generalizability of findings across spatial and temporal scales, climates, or infrastructure types. These gaps leave city leaders without consistent and reliable information to compare the costs and benefits of natural, built, or combined alternatives.
We review the evidence for where the real value of nature lies in cities. We find that the value of urban ES are not constant, but highly variable by social, ecological, and technical context. We identify the elements of context that are the most important for each ES, particularly the type and extent of infrastructure, climate, social preferences, and available space for deployment of green infrastructure. We conclude that some urban ES may have been oversold, especially relative to other non-nature interventions. In other cases, urban nature may be undersold because it provides co-benefits or valued services for which there are few substitutes or alternative interventions. Finally, we discuss how urban ES research needs to more explicitly address environmental justice and equity issues. How nature is managed and prioritized has real distributional consequences for households and communities, and those impacts need to be elevated in urban ES analyses. Our work reveals key insights into the use and value of urban ES and identifies strategies that advance urban sustainability by most efficiently and effectively leveraging the value of natural capital in cities.