Enhanced quality of living: C40 shows that polluted air causes almost 4.5 million premature deaths a year, and in particular afflicts children with conditions such as asthma. Urban forest areas, when properly designed, can help improve air quality, demonstrating the need to distribute trees within urban areas in a way that avoids reinforcing inequalities in health outcomes.^{8 9} The town of Tengah in Singapore offers a good example of how urban planning can provide more healthy living standards by building infrastructure underground.

Enriched physical and mental health: WHO guidelines suggest that green spaces may help to improve mental health. A study in London found that for every one-unit increase in the density of trees per kilometre of street, the number of antidepressant prescriptions fell by 1.18 per 1,000 residents. ^{10 11}With regard to physical health, WHO research estimates that between 23 and 25 per cent of global disease could be avoided through management of green cover. Several studies suggest that green space reduces premature mortality rates.^{12 13 14}

Improved resilience and equality, as part of an adaptation strategy: Deforestation has put some regions much more at risk from the consequences of climate change. Tree planting contributes to protection against landslides and recurring flooding, and hence reinforces the resilience of a city. Eliminating differences in tree coverage and green spaces between areas of a city reduces inequalities, as it provides the benefits of better health and well-being to everyone. An absence of green amenities, typically in low-income areas of a city, creates hotter neighbourhoods and greater exposure to climate risk. Research by Stanford University found that in Sabah (in Malaysian Borneo) a malaria outbreak coincided with a reduction in green coverage. The study found that a 10 per cent rise in forest loss led to a 3 per cent increase in cases of malaria. ¹⁵

Reduced emissions to get closer to the sustainability and climate goals of the Paris agreement: Green spaces help with progress towards the environment goal for decarbonisation. For example, strategic placement of trees in cities can help to cool the air by between two and eight degrees Celsius, thus reducing the urban ’heat island’ effect, and the need for air conditioning by 30 per cent.¹⁶

Understand sustainability drivers and societal targets: To help meet environmental targets, green spaces should be designed with an understanding of both the existing ecological situation and the end goal for achievement. This ‘impact study’ is crucial in order to plan the journey from the starting point to the end goal, embracing the cultural and social dynamics of the city.¹⁷ Assessing the risks should be part of this process: for example, some cities lack information about which zones are more prone to flooding. ¹⁸

Promote equal, fair and integrated urban planning: Compared to city centres, suburbs are often neglected in the development of areas for walking and green spaces. For example, a study in Melbourne found that for each ten kilometres in distance away from the city centre, the tree cover fell by more than 2 per cent. A shortage of urban tree cover can leave suburban areas more vulnerable to the impact of rising air temperatures.¹⁹ Moreover, it is important that the creation of new corridors and green spaces should occur without displacing long-term low-income residents from an area. As an example, the restoration of New York City’s Prospect Park increased property prices and attracted new wealthy residents: this drove poorer residents out of the area, particularly among the black community.²⁰ An integrated perspective is needed, also because walking and cycling corridors must be accompanied by an updated mobility strategy with proper incentives for reducing private car usage.

Do not underestimate the power of community engagement: Community engagement is crucial for obtaining buy-in from local people to green and liveable urban planning. The City of Porto is creating healthy corridors in Campanhã under its Urbinact initiative, which is supported by community engagement initiatives. Active community engagement is also essential for ensuring local involvement in refurbishment and maintenance projects.

Ensure funding and financing: Limited budget resources could hinder the prioritisation of green cover. Cities might therefore consider innovative funding methods for green spaces. For example, Atlanta used impact bonds to develop its Proctor Creek neighbourhood. Washington, DC used similar bonds to fund the development of personnel. ²¹ Other traditional financial instruments could also be leveraged.

Freetown, Sierra Leone

Freetown is one of the most crowded cities in the world, characterised by rapid but uneven growth. For instance, 38 per cent of the city’s expansion had taken place in either medium- or high-risk areas. This hazardous expansion had resulted in the growth of slums in flood-prone areas and environmental degradation. The Mayor has pointed out that building in flood-prone areas is made worse by incomprehensible urban planning and the scarcity of affordable housing. Adding to the challenge, the city does not have the mandate for urban planning decisions.

In January 2019 Mayor Yvonne Aki-Sawyerr launched the ‘Transform Freetown’ plan, a three-year vision for developing the city, to address Freetown’s socioeconomic challenges and environmental vulnerabilities. The plan encompasses four clusters and 11 priority sectors. The clusters are: resilience, human development, a healthy city and urban mobility. The government launched several initiatives under the plan, to address a range of issues from waste management and housing, to improving urban planning and tackling environmental degradation. Among others, the Mayor has pointed to building and constructing (for the first time ever) a wastewater treatment plant; work on a sanitary landfill; the introduction of recycling; and the training and funding of qualified gynaecologists, paediatricians and obstetricians, “which will be a game changer because it will help reduce the number of people who die at birth”.

The #FreetownTheTreeTown campaign is an initiative to reduce erosion and run-off and to increase vegetation cover in the city by 50 per cent by 2022, by planting one million trees. This is seen by the Mayor as a way to combat the rise in air temperature associated with deforestation. “The city has suffered from floods, a loss of diversity and poor air quality, and trees will help restore that.”

For phase one implementation of the campaign in 2019, the city council partnered with various federal ministries, the World Bank and the Environmental Foundation for Africa to plant and grow 500,000 trees in targeted areas to address recurring hazards and avoid potential disasters – such as a series of landslides and floods in 2017 which left more than a 1,000 inhabitants dead or missing and had an economic cost of over EUR 25.5 million (USD 30 million)²² , restore natural ecosystems, and protect the water supply and sanitation infrastructure.

As of 2020, the city had planted 245,000 seedlings and nursed 15 different species of trees across a number of sites. They will continue planting them in houses, schools, public spaces and office areas. Followed by an assessment of the tree canopy through machine learning, tree growth will be tracked through a locally developed Treetracker app, and the survival of the trees will be ensured through employment community stewards and the issue of impact tokens as a reward for good care. The initiative has created 553 green jobs amongst tree planting communities to ensure long-term sustainability of the strategy. “They are based in communities, they have responsibility for particular tree planting zones, for tree plant catchment areas, and they water them. But there is a jobs element here, also built into the nature of the trees that are planted. We have gone for economic trees: you are able to harvest mangos, cashews, fruits, moringa herbs, which have a commercial value. The community or the household will benefit from that.”

The city has also appointed climate change ambassadors, the local chiefs, to create awareness and avoid destruction of trees for fuel in cooking, as “82 per cent of the fuel used in Freetown for cooking is wood-based”.

The objective is to ensure equitable distribution of vegetation coverage across the city and to include the entire community in the process so that Freetown becomes more resilient to future challenges. ^{23 24 25}

Lisbon, Portugal

As the use of cars increased, Lisbon’s streets became more congested. This led to a reduction in space for pedestrians and exposed the problems with urban design that prioritised making space available for cars and other vehicles.

To deal with the challenge, the city prioritised the development of pedestrian and cycling corridors. The city is building cycle paths in the city’s central artery and uptown avenues. It is working towards having 200km of bike lanes by the end of 2021, so that 93 per cent of the population has access to a cycle lane within 300 metres of their home. It is also creating a total of 27 cycle-pedestrian bridges.^{26 27}

Lisbon has also taken initiatives to refurbish community squares as green public spaces. For example Martim Moniz Square, historically a commercial space, was transformed by grass covering and roof gardens with the aim of ‘returning the space to the city’. Praça de Espanha, a disorganised area, was turned into a green zone dedicated to walking and cycling.^{28 29}

Lisbon launched ’LIFE LUNGS’ to implement a municipal climate adaptation strategy for increasing the resilience of the city through green infrastructure. By developing more green spaces, it aims to tackle rising temperatures caused by urban heat islands.³⁰Only two days after Lisbon was awarded the title of European Green Capital in 2020, 4,500 people from all over the city and surrounding areas planted 20,000 trees. The city plans to be 100% carbon-neutral by 2050.^{31 32}

Lisbon is also connecting its green areas to the Vale de Alcântara green corridor. It connects the city’s natural amenities, including Monsanto Park and the Tagus River, with cycle paths and walkways, providing greater access to green spaces.³³

Shiraz, Iran

Growth in the population led to excessive construction projects in the city, poor living conditions, pollution and high energy consumption. To deal with the situation, the municipality started reforestation of the city’s periphery under an initiative called ‘the Green City’ project, which ran from 2008-2018.

The project targeted all citizens of the city, with a special focus on those living in areas of high unemployment and crime and also on tourists visiting the city.

The project had four elements: urban forest development, roof parks, linear parks and roof gardens. The government created green spaces, recreational areas, linear parks along streets and roof parks. It also encouraged planting on rooftops, and tax rebates were offered to private sector construction projects that were in alignment with the city’s development plan.

As a result, the per capita green space increased from 13m2 to 85m2. The project also increased ground water resources and produced 325,000 cubic metres of oxygen each day, improving the air quality in the city.

2,876 hectares around the city were transformed into forests of olive trees. Olive oil from the trees increased the municipal income, and reduced the city’s dependency on imports of olive oil. Another outcome was the prevention of ‘illegal’ construction and settlements around the city borders.

Following successful cooperation between authorities at different levels, state and local, a national law has been proposed for the implementation of similar projects in Fars Province (covering an area of 40,000 hectares). Other cities have signed an agreement to follow the example of Shiraz.³⁴

1. UN-Habitat (2013.), Streets as Public Spaces and Drivers of Urban Prosperity, quoted in SDSN: Indicators and monitoring framework. (2020)
2. CNBC: These are the world’s most liveable cities in 2019. (2019)
3. Senseable City Lab: Exploring the Green Canopy in cities around the world. (2017)
4. Another Development: Urban planning and the importance of green space in cities. (2020)
5. C40 Cities: Focused Acceleration: A strategic approach to climate action in cities to 2030. (2017)
6. C40 Cities: Green and healthy streets. (2020)
7. Senseable City Lab: Exploring the Green Canopy in cities around the world. (2017)
8. University of Washington: Green cities: Good health. (2018)
9. C40 Cities: Green and healthy streets. (2020)
10. American Planning Association: The benefits of street-scale features for walking and biking. (2015)
11. Irrigazette: Green space with urban or suburban environment. (2017)
12. World Resources Institute: Green, Equitable, Inclusive: Redefining Public Spaces. (2020)
13. Barcelona Institute for Global Health: Why Cities Need Green Space More than Ever?. (2020)
14. Food and Agriculture Organization of the United Nations: Building greener cities: nine benefits of urban trees. (2016)
15. National Geographic: Deforestation is leading to more infectious diseases in humans. (2019)
16. Food and Agriculture Organization of the United Nations: Building greener cities: nine benefits of urban trees. (2016)
17. World Resources Institute: Green Space: An Underestimated Tool to Create More Equal Cities. (2020)
18. Bill Gates: How to avoid a climate disaster. Bill Gates. 2021
19. The Conversation: Fewer trees leave the outer suburbs out in the heat. (2014)
20. World Resources Institute: Green Space: An Underestimated Tool to Create More Equal Cities. (2020)
21. Ibid.
22. World Bank Blogs: The 3 challenges in building urban resilience in Freetown. (2019)
23. Freetown City Council: Transform Freetown: An overview | 2019 - 2022. (2019)
24. World Bank: An Obstacle or Opportunity? Building Urban Resilience in Freetown. (2019)
25. UN Environment Programme: Transforming Sierra Leone's capital. (2020)
26. USGRDCO: Evolution Is a Choice for Lisbon, the New 2020 Green European Capital. (2020)
27. European Cyclists’ Federation: MOVE Lisboa: what is on the horizon for cycling in Lisbon? (2020)
28. The New York Times: A Lisbon Home With a Vertical Garden. (2016)
29. Failed Architecture: A Warning to Lisbon: The Fight for Meaning in Martim Moniz. (2020)
30. Climate Adapt: Towards a more resilient Lisbon Urban Green Infrastructure as an adaptation to climate change (LIFE LUNGS). (2020)
31. European Commission: 2020-Lisbon. (2020)
32. Euronews: Lisbon kicks-off year as European Green Capital 2020. (2020)
33. Lisbon City Council: Praça de Espanha, Green and leisure area. (2020)
34. Urban Sustainability Exchange: Shiraz - The Green City. (2018)

You may access the links to these sources, where available, on page 148 of the Urban Future with a Purpose study.