Nature-based Solutions for Urban Ecosystem

Cities have not been designed with a human-centered view: city planning follows economic interests, where buildings, traffic circulation, companies and industries are on a higher hierarchical level. What are nature-based solutions and what can they do to help cities become more climate resilient?

By Emiliano Campisi | YPA Italy

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It has been estimated that by 2050 about 70-75% of the world population will be living in cities and that roughly 80% of the global GDP will come from urban areas. What will this mean? Increased energy consumption, heavy resource depletion, high population densities and, as a consequence, higher greenhouse gases (GHG) emissions. If we combine this projection with the already expected climate change effects, a clearly problematic spectrum emerges. 

2007 marked a historic moment: for the first time the majority of the world population was living in cities rather than in smaller centers or rural areas. Since the industrial revolution the rate of people moving from rural to urban areas has been constantly increasing. Dreams of better life conditions encouraged millions of workers to abandon the countryside, seeking fortune in the cities that were full of jobs and other opportunities. Nowadays, after this continuous growth, cities of developed countries are experiencing a counter trend of depopulation, mostly due to the emerging desire for better liveability conditions. 

Cities have not been designed with a human-centered approach in general: their planning follows economic interests, where buildings, traffic circulation, companies and industries are on a higher hierarchical level. 

However, everyone who has travelled a bit, when visiting or living in a city, has experienced at least one time the feeling of finding themselves in a human-centred context: large and diffused green spaces and pedestrian zones, integrated mobility, efficient public services and no stress. What’s the role of nature here? In particular, what are nature-based solutions and what can they do to help cities in the transition towards more climate resilient and liveable cities?

The European Commission states that nature-based solutions (NBSs) are “inspired and supported by nature, are cost-effective, simultaneously provide environmental, social and economic benefits and help build resilience. Such solutions bring more, and more diverse, nature and natural features and processes into cities, landscapes, and seascapes, through locally adapted, resource-efficient and systemic interventions”.

When implemented in cities, NBSs help climate change mitigation and adaptation. They are useful to tackle biodiversity loss, they function as a carbon sink, sequestering carbon dioxide, they help in moderating the impact of high temperatures, they diminish pollution, they capture stormwater, they create jobs, they can be used as public spaces and for educational purposes, and they can provide many other co-benefits.

As average global temperatures increase, living in many cities of the world will become more and more difficult, due to warmer cities and more intense urban heat islands (UHIs). The latter are caused by the concentration of people and human activities in a relatively small place. Heating or cooling our buildings implies energy consumption and heat release, making the surroundings warmer. Traffic congestion, cemented streets, artificial materials of the buildings, all of this keep our cities warmer than the neighboring areas. 

In this scenario, NBSs can help in cooling cities through various solutions. Citizens, architects, designers, engineers and politicians have to work all together to reduce people’s impact on urban areas, integrating nature with buildings and streets in urban planning processes. The first and most feasible solution is to plant the appropriate trees in the right places: indeed, their leaves will filter out partially the direct sun rays, limiting the heating of the streets. Using green roofs, which are roofs of buildings covered in plants, also may help to cool cities down, and using lighter-coloured materials in buildings does too, as light colours reflect more sunlight, trapping less heat inside the urban canopy.

A study from the IAU Ile-de France, cited during the event “Nature for Climate & Biodiversity in Cities: entrepreneurship, co-creation and engagement”, shows that implementing NBSs could decrease temperatures in city center areas by 2°C on average. But the most interesting thing is that by doing this a reduction in energy demand by 20% will follow, leading to a decisive cut in GHG emissions. This at relatively low costs, which makes NBSs very attractive to policy makers.

It is undoubtedly true that NBSs need to be designed case by case, as every city has a different structure and different needs, but, on the other hand, their potential in helping mitigate and adapt to the impacts of climate change in urban areas is crystal clear.