Climate

Green spaces deliver ecosystem services that boost cities’ resilience to climate change and strengthen their sustainability. They can attenuate the impacts of extreme weather events such as heat waves, heavy rainfalls, storms and floods, as well as slow-onset risks like drought, land erosion, and landslides. A recent SWAC analysis illustrates that green spaces can help reduce air pollution in urban agglomerations in Africa. In addition to sequestering and storing carbon, they also contribute to water quality and even biodiversity conservation. These spaces are being lost as urban agglomerations become increasingly compact.

The green spaces indicator is the fraction of an urban agglomeration covered by green space. A value of 0.25 means that green space covers 25% of the urban footprint. The colour of the bubbles represents the indicator value for urban agglomerations in 2015 or 2020, depending on the selection on the map. Urban agglomerations are defined following functional criteria as continuously built-up areas with 10,000 people or more. The size of the bubbles represents the size of the urban population. The map shows the urban agglomeration boundaries, the urban green spaces indicators, and the land cover information from ESA World Cover for years 2020 and 2021 at detailed zoom levels. Click on the bubbles to see more details about each city.

Mapping green spaces

Proximity to green spaces by local populations

Cities with similar absolute levels of green space may exhibit significant variations in terms of the proximity of their populations to these areas. This is important because availability of green space within cities is not enough, people need to live near (i.e. within 300 meters) green spaces of significant size and with trees to really benefit from their cooling effects during heatwaves. The data visualisation below shows a selection of cities across the continent with different green space covers and shares of populations located in proximity to green spaces. An enhanced understanding of these spatial dynamics can help devise targeted strategies to preserve and leverage green spaces in the face of rapid urbanisation and climate change.

Examples such as Accra versus Abuja, Bangui versus Algiers, and Luanda versus Benin City all demonstrate that cities with similar green space coverage can have different proportions of their populations located close to them. Well-distributed green spaces throughout the urban landscape represent one smart strategy to mitigate the effects of extreme heat.

Example: Accra and Abuja. Both urban agglomerations have the same availability of green space, approximately 20% of the urban footprint, but they show drastically different proportions of the population who can benefit from their cooling effects during a heat wave — 16% in Accra and 55% in Abuja. Green spaces could, therefore, offer an important nature-based solution to heatwaves in Abuja, contributing to a more liveable, sustainable, and resilient city. In Accra, the lack of green spaces distributed throughout the city can exacerbate vulnerability to climate change and deteriorate liveability.

POLICY PERSPECTIVES – How to enhance the availability and accessibility of green space?

Including green space provision in urban planning instruments can enable greater availability and accessibility (e.g., Kumasi’s Master Plan, Greening Lagos, Cape Town Green Infrastructure Programme, Dar es Salaam’s Plan). Some plans designate existing green spaces for conservation, whilst others identify brownfield sites for restoration, helping to minimise trade-offs with rapid urbanisation and greater compactness.

Plans alone are not necessarily sufficient to ensure green space but require horizontal and vertical coordination across government, as well as allocating resources (i.e., funds and staff) for monitoring and enforcement. Ensuring access to data on the location, size, and types of green space allows a better understanding of the needs and challenges to design placed-based plans, set clear targets, monitor and evaluate progress of such plans, as well as target interventions. For example, measuring and mapping access to green space, as seen above, can allow the identification of underserved areas to help focus the allocation of resources to maximise their benefits to the community (as seen in Dar es Salaam using artificial intelligence to map existing green spaces). Setting a proximity target, such as “every household is located within a 5-minute walking distance of green space,” will help to ensure access and guide urban planning in strategically locating and designing green spaces (e.g. Accessible Natural Greenspace Standard in England ).

Some legal obligations, such as developer fees (i.e., payment by developers to build on urban land) can help fund the conservation and maintenance of urban green spaces and ensure access to it (e.g. Cape Town developers fees or negotiated contributions that are used to finance public infrastructure). Another measure that could help maintain green spaces as the city grows and densifies is to require a minimum portion of future land development to be dedicated to public green spaces (as specified for future developments in Eko Atlantic City in Lagos).

Potential for digitalisation and market-based mechanisms for tree restoration

Green bonds offer a way to get financing for urban green space creation, restoration, and conservation. They could help finance parks, gardens, and other public green spaces, as these can help to improve air quality and urban biodiversity. The development of a green bond market requires investment in training staff in environmental, social, and governance regulations, clear guidelines for financial actors, and incentives to support climate-resilient infrastructure. To date, only Cape Town has issued municipal green bonds, to finance energy and low-carbon transport, but several other cities have also expressed interest from Lagos to Cairo.

An interesting example from West Africa is Freetown in Sierra Leone, which demonstrates an alternative approach to secure financing and long-term positive impact for resilience and adaptation. Through a community growing model, reforestation is co-designed and co-managed by both the community and the city government. The community plays a role in deciding where to plant the trees and receives payments for planting, nurturing, and digitally tracking trees using a dedicated mobile app. This digital system tracks each planted tree with a unique geotagged record, and financial compensation for the growers is tied to continued tracking. Furthermore, seedlings are sourced from local nurseries to support the local economy. They went further and tokenized the planted trees, to foster their maintenance and growth. These tokens are sold to corporations and institutions with climate or corporate social responsibility targets, offering impact investment opportunities. Investors purchase these tokens wholesale as carbon offsets from the city, facilitated by a third-party fund manager. The revenue generated is earmarked for funding further reforestation and nature-based solutions, establishing a self-sustaining model.

Preserving and increasing urban green space is a considerable challenge considering other more visible matters like poverty, transport and housing. However, improving and increasing urban green space is, at the same time, a great opportunity. Urban green infrastructure planning, backed with resources and political will, leads to more resilient and sustainable cities.

Data sources:

This indicator combines two data sources. Africapolis provides the spatial boundaries of the urban agglomerations with at least 10 000 people and with less than 200 metres between buildings. The European Space Agency’s (ESA, 2020) WorldCover provides a land cover map at 10 metres of spatial resolution and uses radar as well as optical satellite imagery.  The availability of green space in cities is the sum of the area of three types of land cover (km²) including trees, shrubland, and grassland divided by the total area of the urban agglomeration (km²) as defined by Africapolis.

Citation:

OECD/SWAC (2023), “Urban Green Space Dataset”, Mapping Territorial Transformations in Africa (MAPTA), https://mapping-africa-transformations.org/climate (accessed on DD-MM-YYYY).