On the 31st of October, we will celebrate World Cities Day! This day is recognized by the United Nations, and for this year, they chose the theme “People-Centred Smart Cities”.

Our approach, in celebration of this day, will look at how we can make our cities greener!

Green spaces and trees in our cities do more than just look pretty; they help us, our neighbourhoods, and the planet in many important ways. This is especially true as cities grow and face challenges like heat, pollution, and stormwater overflow. Planting and caring for urban trees is a powerful step towards better, healthier cities.

We can reflect on our own experiences. Let’s think of a time that we were in the city, in summer, and how hot the city is. As soon as we step outside of the city, we notice the drop in temperature, and we notice how the air becomes fresher, cooler, and overall more pleasant. Does this sound relatable?

An image that often circulates on social media, of how Germany transformed Düsseldorf into a greener city*

Let’s consider why trees and green spaces are important

Cooling and better climate: Cities often become hotter than surrounding rural areas, a problem called the “urban heat island” effect. Trees provide shade, and their leaves release water vapour (transpiration), which helps cool the air. Green roofs and parks also reduce temperatures and help lower energy use for air-conditioning.

Cleaner air and less flood risk: Trees filter air by capturing tiny particles and absorbing gases like nitrogen oxides and ozone. They also reduce storm-water runoff: when rain falls on leaves, branches, and permeable soil rather than bare pavement, less water floods into drains and rivers.

People’s health and well-being: Being near trees and green spaces lowers stress, improves mood, helps recovery in hospital settings, and supports physical activity.  Additionally, trees reduce heat-related health risks and improve general comfort in hot weather.

City life, community, and economy: Well-designed green areas make cities more livable. Shops and cafés on tree-lined streets tend to do better; property values often rise where tree cover is good. Trees also provide a natural setting for social life, play, relaxation and strengthen community identity.

The example of Basel, Switzerland, and its greenery**

Now, we can reflect on some examples of how cities are using trees and green spaces.

Urban forests: Also known as Miyawaki Forests. Some cities treat their tree cover as a “forest” within the city, with many trees planted in clusters or along streets. These help maximise the benefits. Learn more about this topic here.

Green roofs and rooftop planting: Buildings with vegetation on their roofs help reduce heat gain, improve insulation, and create new green spaces where ground space is limited.

Street trees and pocket parks: Even smaller green zones, such as trees planted along sidewalks, small parks in blocks, make a difference for local residents.

Equity in tree access: It’s important that every neighbourhood – rich or poor – gets good tree cover. Some places still have fewer trees in low-income areas.

In the city of Nouakchott, the government has planted hundreds of trees next to the main road leading to the airport.

See, even in the Sahara Desert (As illustrated in the image above), one can try to make a city greener!

Now, equipped with the above information and understanding, we can consider our own actions. What can we do, together, to make our cities greener?

Plant new trees in strategic spots near schools, along busy roads, on rooftops, and in parks.

Partner with local governments and community groups to maintain trees and green spaces.

Choose tree species suited for city conditions (pollution, heat, limited soil).

Advocate for policies that preserve existing trees and encourage green roofs / walls.

Promote the message: “Every tree counts” – even a small green patch helps!

On World Cities Day this year, let’s celebrate how trees and green spaces shape a better urban life. When we plant a tree or protect a green roof, we are not just adding beauty. We are improving air quality, cooling our cities, supporting people’s well-being, and strengthening communities!

If you are going to plant a tree in your city, this World Cities Day, please remember to tell us about it! We would love to hear from you and write an inspiring story about your planting!

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References and further reading:
https://urbem.co/en/
https://www.epa.gov/soakuptherain/soak-rain-trees-help-reduce-runoff
https://en.wikipedia.org/wiki/Urban_heat_island
https://pmc.ncbi.nlm.nih.gov/articles/PMC5663018/
https://www.evergreeninfrastructure.com.au/blog/greening-urban-spaces
https://cnr.ncsu.edu/news/2023/06/urban-tree-planting-equity

*Image source: Facebook
**Image source: https://www.pexels.com