Urban green and blue areas

What is it?

Nature-based solutions (NbS) in urban areas involve maintaining, restoring and creating new green and blue spaces. Urban green and blue spaces are public and private open spaces located in urban areas, primarily covered by vegetation, or water. Urban NbS emerge as an effective tool in tackling multiple societal challenges in urban areas, such as addressing climate change impacts (e.g. heat, flooding), and human health issues, while also contributing to reducing the loss of biodiversity. Not only are they an important part of cities and urban spatial planning, but they also form part of the common services that are provided by a city, typically serving as a health-promoting setting for all members of the community. Urban NbS types range from individual small-scale NbS on buildings or along streets, to large-scale NbS such as urban forests or rivers across an urban areas, connecting to peri-urban areas and the wider landscape, including:

• Green and blue structures connected to grey structures: Green and blue structures attached to street, bicycle lane, pedestrian path, parking lots and drainage systems, such as street trees, raingardens, flowerbeds, roadside green and constructed wetlands.

• Parks and (semi-) natural green areas: mainly public or semi-public larger areas dominated by green features, such as parks, urban forests, greenways, botanical gardens and cemetery

• Gardens: Mainly private areas managed for (at least some) food production, such as allotment gardens, courtyards and community gardens.

• Building greens: Green structures attached to a building, such as a green roof or green wall.

• Water bodies: (Semi-) natural water bodies such as lakes, rivers, canals and wetlands.

How do these options work?

City governments, municipalities and urban dwellers worldwide are planting vegetation in streets, parks, gardens and on roofs to help offset the negative impacts of increased urban density. Collectively, protecting existing and planting new native vegetation has great potential to curb urban biodiversity loss and ensure the multiple other benefits that urban spaces provide (see section below on impacts). The quality of green spaces is measured by factors such as connectivity, vegetation, accessibility (i.e. providing equal access to nature), and security.

Integrating urban NBS into urban planning can ensure a long-term regeneration approach to use green spaces properly for multiple benefits. For example, urban initiatives such as water regulation schemes, brownfield development as well as wilder, woodland-type, and untamed elements, with more areas for child development, and can also include novel ideas such as green bus shelter roofs.

Where can urban spaces be applied?

Urban green spaces work in almost any urban environment where there is space or land that can be converted or regenerated. One of the most essential prerequisites is accessibility of the space to residents.

What are the impacts of urban green spaces?

Urban NbS play a critical role in maintaining a liveable and health urban environment, as they provide multiple benefits to urban populations. For example, the mitigation of heat during summer (trees provide shade and cool the air), enhanced water retention hence reducing the risk of stormwater flooding as well providing space to reconnect with nature or meeting other people, and stimulate outdoor recreation and activities. The Naturvation project has created maps looking at the heat mitigation potential in 775 European cities.

Despite their relative small scale, urban NbS, such as trees and urban forests, also support the storage and sequestration of carbon, although the contribution to climate change mitigation is modest. They are also critical for protecting local biodiversity and can sometimes act as biological corridors to facilitate the movement of fauna, preventing fragmentation and isolation of wildlife. From a social standpoint, not only are they able to improve the health and well-being of local citizens but they can also help to promote the interaction between people which helps to develop social ties and build a sense of community among a city’s residents. From an economic point of view, urban NbS also provide opportunities, for example by reducing energy demands in buildings through green rooves (that can provide insulation) and shade provided by trees. It is important that urban NbS are inclusive: accessible to all who live in the urban environment and not just the high-end neighbourhoods.