There are just two more train stops until the very north end of Denmark after Aarhus, the largest Danish port and the second largest city with roughly 300.000 inhabitants. The northern landscapes are so different and so exciting just for that same reason. In Aarhus we’ve spent three days with the other 18 partner-organisations in the project that is just starting, a HORIZON 2020 project about re-greening urban environments. Or to put it simple, the project is about how and why bring nature and its functions back to our cities, as green and by nature-inspired way of adapting to climate change. Solutions based on nature can address many challenges within cities. Cities are complex systems, we dare to say cities are like men-built organisms, while nature has a solution for everything. Nature has been developing solutions for millions of years and it’s called evolution, we just do not know enough about it yet.

Cities as two-way hot-spots

Nowadays more than half of the world population live in urban areas, but towards 2050’s it will be more than three quarters and there will be many more challenges brought by climate crises and degraded nature as a result of our human activities. Cities are hot-spots for both challenges and solutions, so we have to experiment and innovate the cities’ systems. Nature-based solutions can help and that is what this project is about.

Another important thing that the project is about is the variety of partners – we are a mix of universities and research institutions with expertise, practitioners working with entrepreneurs, start-ups and innovative financing models and the cities – three urban living labs in Europe and three in China. Six urban areas are partners in the project with concrete challenges and solutions to be implemented and learnt from: Danish Aarhus, French Île-de-France or Paris region and Velika Gorica, the sixth largest urban area in Croatia. In China the scale is different but cases and living labs equally important for the project – we shall learn together with and from Beijing, Shanghai, and Ningbo.

St. Kjeld as one example of “the how?”

On our way up north to Aarhus to meet this exciting group of partners and kick-start the project, we’ve had a half-day stop in Copenhagen, just enough to visit St. Kjeld, one of the first urban climate-quartier, built as a climate adaptation measure in the city. What is special with St. Kjeld is that the functions of nature and specific plants species are used instead of human-built technical infrastructure to help with drainage of heavy rainwaters and to prevent flooding of the streets and squares but also to store water in dry periods and cool people chilling in the park while kids are playing. These green islands help as well to reduce urban heat islands in warm summer days – less concrete and bricks substituted by greens mean lower surface that absorb and radiate back the heat. More greens cool the cities naturally. Why don’t we use it more?

Nature-based solutions or NBS can provide one-third of cost-effective climate mitigation!

In Aarhus, we’ve heard about more such climate-adaptation measures inspired by nature. The point is to bring functions provided by natural ecosystems back to urban areas, to the cities and to use multiple benefits nature brings us – not just drainage of rainwaters but also filtering the air, producing more oxygen, increasing evapotranspiration thus decreasing high temperatures in summer heat extremes, providing new habitats for plant and animal species and creating micro-green networks that capillary-grow throughout our cities and increase biodiversity. It creates healthier and more pleasant environment to live in, which reduces the costs of treating diseases caused by low quality of urban air, for example.

It is also more cost-efficient, green infrastructure is 2-4 times cheaper compared to costs of “grey” unit of function or construction. It is called nature-based solutions or NBS. Researchers indicate that NBS can provide over one-third of the cost-effective climate mitigation needed between now and 2030 to stabilize warming to below 2 °C.

What that can be, the NBS in our cities?

Those can be green roofs or green facades on city buildings instead of more glass, steel and concrete. It is important that they resemble and function naturally as much as possible, not to create technical solutions only covered by green but under surface consuming lot of energy to keep them going. Not every green-looking solution is a nature-based solution.

Those can be green parking lots and children playgrounds instead of asphalt or artificial pavements often made of plastics (even if recycled, it still is plastics) that leaks as microplastics with rainwaters and comes back to our food chains. Those can be urban gardens and larger parks with many tiny spots for birds and insects, so important pollinators, tiny bees, moths, butterflies and other living creatures supporting the production of 87 of the leading food crops worldwide. You’d say – we do not produce food, cities are not agricultural lands, why do we need pollinators in cities? Well, most of our cities are surrounded by agricultural land – for example, the area of whole Aarhus municipality is 5 times larger than only its urban area and it is in agricultural production.

Life in cities depends on biodiversity surrounding the urban core. With this project we shall know more what kind of solutions suit us most, why, what are the benefits for our society, for people, not only economy. We shall learn how to use natural functions to solve urban challenges such as floods and urban heat islands or air pollution. Ultimately, we shall learn together to value and to bring back nature to our cities. In Croatia, we shall experiment with Velika Gorica and help the city system to develop in more (self)sustainable way – from green roofs and use of solar power to draining rainwater out with restored riverbeds, creeks and channels, growing more urban gardens and increasing biodiversity, with circulating materials and energy in local value-chains with minimal wasting, because in nature nothing is wasted. Let’s try it together, let’s Re-Green our cities!

By Sandra Vlašić

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