courtesy  :  natural history museum

Why we need green spaces in cities

By 2050, 68% of the global population will live in cities. That’s 2.5 billion more people than today. In Europe, three out of four of us already live in urban areas, and the consequences of that are becoming clear.

Researchers estimate that nine million people die every year as a direct result of air pollution. In London, two million people – of which 400,000 are children – are living in areas with toxic air.

As our cities grow and more people move into already crowded spaces, what do we need to do to transform our urban areas into healthy places to live? An increasing body of research tells us that we should be letting nature back in.

Dr Cecil Konijnendijk is a Professor of Urban Forestry at the University of British Colombia (UBC). He studies the role of nature and green spaces in cities and towns, and how we can use the natural world to make urban environments healthier and more liveable.

‘Research shows really clearly that we need nature in our surroundings. We need trees in our streets, plants in our gardens and flowers on our balcony. We need nature as our neighbour all the time.

‘We have a responsibility as human beings to take care of nature in our cities. In return, the benefits to our health would be huge.’

The urban heat island effect

Green spaces in cities mitigate the effects of pollution and can reduce a phenomenon known as the urban heat island effect, which refers to heat trapped in built-up areas.

The urban heat island effect appears in towns and cities as a result of human activity. The heat generated by people, transport, shops and industry is trapped in the narrow roads and concrete structures, unable to escape to the atmosphere. This can bring the temperature in urban areas up 3-4°C higher than the surrounding countryside, and with that comes a vicious cycle.

Increased temperatures in summer leads to an increased demand for cooling. This expands our energy consumption, which in turn intensifies fossil fuel consumption, increasing pollutants in the air and harmful smog on our streets.

Hotter pavements also damage the water cycle. In summer, surface temperatures can be a staggering 50°C hotter than the surrounding air, and that heat is transferred to the rainwater that drains into our sewers, which in turn raises water temperatures as it is released into streams, rivers and lakes. This can be destructive to aquatic ecosystems, as changes in water temperature can be stressful or even fatal for marine life.

Green roofs: miniature urban forests

Planning cities to include green spaces wherever possible is the first step in making our urban areas healthier. For example, adding a layer of vegetation to rooftops and creating green roofs has proven to reduce the urban heat island effect.

Having soil, plants and greenery on our roofs would both reduce surface temperature and serve as insulation for the structures below, reducing the energy needed to heat and cool the buildings. Green roofs can also help regulate rainwater, trapping it as it falls and filtering out pollutants.

Trees in our streets also play their part, and a variety of tree species can have a profound effect.

‘By increasing the diversity of trees on our streets we can create miniature forests,’ Cecil explains. ‘This has already started to be implemented in cities like Singapore, where they are mixing human structures with many different tree species.

‘These miniature forests in our cities create ecosystems, bringing a diversity of insect and bird species which, in turn, keep the trees healthy. If we allow ecosystems to flourish, we have to spend less resources on maintaining them.’

Cecil recommends going beyond creating pockets of nature within a city. He says, ‘If we give space to natural processes and link up our green spaces, we can create flourishing and wild ecosystems in man-made environments. There were no sightings of the critically endangered smooth-coated otter in Singapore for decades. Now they are returning to the city, because of its dedication to nature.’

Green cities mean giving up some control of our surroundings – but for our long-term benefit.

‘We need to get used to letting go and try not to manage everything. Some natural spaces are messy, but that’s a good thing! Messy nature isn’t just a great habitat for wildlife but it’s good for children to play in. Children’s depression and ADHD is on the rise and one of the reasons is our disconnect from nature.’

Simply having access to green spaces in cities can do wonders for our stress levels and concentration at work.