Why should we care?

High summer temperatures, urban flooding, decreasing air quality, lack of public space in densely populated areas: these are some challenges cities  are currently tackling that affect all who live in urban areas. Unfortunately, as climate change and urbanization occurs, these problems will continue to worsen. This is where urban green infrastructure (UGI) can help. But what is it, why is it important and what benefits does it bring – let’s break it down together.

What is urban green infrastructure?

As you close your eyes and imagine a city, you might picture towering skyscrapers, busy roads, and bustling streets. Probably this is the first association that  will come to mind – just a grey and noisy landscape. While the engineering solutions such as the sewage system and intricate roadways make up a large part of the city, it also encompasses nature or so-called urban green infrastructure (UGI). UGI comes under the umbrella of the broader definition of Nature Based Solutions – urban solutions inspired by nature. In 2013 the European Commission officially defined UGI as 

‘‘Strategically planned/considered network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services”.

 You can easily see UGI around you – it  includes trees, green roofs and green facades, urban forests, parks, permeable pavers and other elements of nature. For example, the project Green Surge  classifies ugi with 44 elements.

Source: Unsplash

All parts contribute to the quality of the urban environment and life of citizens through the various environmental, economic and social benefits they provide. 

Urban green infrastructure can help to:

• Reduce the air temperature 
• Connect local community
• Increase biodiversity
• Provide new job opportunities
• Decrease the noise pollution and many others.

The nuts and bolts of UGI

UGI is multifunctional and simultaneously provides a diversity of goods. For example parks can be a space for social gathering and at the same time a cooling spot during the hot weather.  A green roof can be a place for the local food production and to collect the rainwater. Let’s take a closer look at the 3 urban challenges and see how in each case  the UGI can help to improve it. 

1. URBAN HEAT 

Consequences: Like a rise in body temperature, a rise in the earth’s temperature is the clearest signal we can get from the world of an emergency that something needs to be done. The heatwave in Europe last summer was a very telling example – Portugal and Spain set a record in persistent heat waves and reached extreme 47ºC. In Spain more than 4000 people lost their lives in 2022. The temperatures in the dense city areas are intensified by the artificial materials and reflecting surfaces like concrete, asphalt, mirrors and glass. Density limits the air circulation which further enhances this negative effect.

How UGI helps: Trees and other urban green elements have an ability to reduce the temperatures through the shadow they provide and transpiration – the process of water release in the form of steam through the leaves. As air temperature increases, so does water evaporation. A study of 293 cities in Europe shows that in some areas, the cooling impact of trees can lower the summertime surface temperature by up to 12°C. 

2. BIODIVERSITY LOSS 

Consequences: Another urban challenge, which in turn has a direct impact on global food systems and thus on our health, is the loss of biodiversity – all the different kinds of life you can find around you, such as animals, plants or insects. All species and organisms play a vital role in sustaining life on Earth, and we depend on them. Pollinators like bees are essential for 75% of crop products like Cocoa beans. Imagine a world without chocolate! That’s how it would be without pollinators. Despite the high importance, 40% of the world’s insect species are threatened with extinction. Reduced food availability, higher production costs, lower quality products and  thus health consequences will be the price to pay. 

How UGI helps: Urban greenery provides habitat for bees and other species. To make spaces more attractive to pollinators, cities should use a variety of plants and reduce the use of pesticides. For promotion of the pollinators-friendly areas connectivity plays a great role as it encourages the pollinators to cross the city. Following these principles, the Farfalle in ToUr project was created in Turin in 2014 with the goal of  preserving butterflies. Check it out in the video below.

3. URBAN FLOODS 

Consequences: The current “grey” infrastructure was planned many years ago with a different amount of rainfall in mind, but due to climate change, more and more rain will fall on cities with greater frequency. The old infrastructure  can no longer cope with the increasing pressure, leading to its destruction and urban floods. In Germany alone, more than 180 people died and many were  missing because of severe flooding in July 2021. €30 billion has been allocated to rebuild homes, businesses and infrastructure in the cities most affected. All this confirms the importance of finding new ways to collect rainwater, and this is where nature can come to the rescue. 

How UGI helps: UGI like green roofs, rain water gardens and other permeable surfaces collect rainwater without giving it away to the central sewer system. This approach to absorbing rainwater where it falls is called the “Sponge City“ concept and originally came from China. By collecting water, UGI reduces the pressure on sewer systems and thus the risk of urban floods. European cities are adopting China’s experience. Look how Berlin has integrated this innovative approach to stormwater management.

To sum up

More and more cities in Europe and beyond are seeing the potential in urban green infrastructure as a tool for overcoming urban challenges. They incorporate it into local urban and climate change policies and strategies. And this is where the knowledge aspect comes to the fore. Aiming to foster the know-how exchange, the Urban Nature Atlas (UNA)  data set has been created with over 1000 nature-inspired projects around the world. Everyone, from policy makers to the interested citizens, can find inspiring examples of urban green infrastructure and the value it brings.

4 UGI FACTS: 

1. 1 sq.m. of green roof can capture 137 litres of water that is relevant to one bathtub. 
2. The World Health Organization (WHO) recommends that citizens should be able to access 1 ha of green space, which is about 2 soccer fields, within a 5-minute walk of their home.
3. In 1984, Edward Wilson introduced the term “Biophilia,” which suggests that nature is genetically predisposed to attract humans.
4. 6th June – is the World Green Roof Day. Save the date!

KEY TAKEAWAYS:

1. Green infrastructure or “lungs of the city” is a vital integrative part of the city and must be designed as a connected system, in accordance with the water, transport and other engineering networks.
2. In contrast to the grey infrastructure, the green is multifunctional – it brings several benefits to citizens simultaneously. 
3. Connectivity of the urban areas is important since fragmentation leads to disruption of its ecological functions. 

DO YOU WANT TO KNOW MORE: 

1. Green Surge Project: https://ign.ku.dk/english/green-surge/
2. Green Envelope ARUP: www.arup.com/perspectives/publications/research/section/cities-alive-green-building-envelope 
3. Ted Talk: How to transform sinking cities into landscapes that fight floods www.ted.com/talks/kotchakorn_voraakhom_how_to_transform_sinking_cities_into_landscapes_that_fight_floods 
4. What’s that green Podcast