Circular cities imitate the behavior of nature to minimize its impact by recycling and reusing resources, and by multiplying green infrastructures. Credit: Chuttersnap.

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By the middle of this century, 70% of the global population will be concentrated in cities. This widespread urban growth will bring with it an increase in the consumption of resources, but also in the waste generated, multiplying the carbon footprint in the atmosphere. To curb this impact, cities are looking to implement new sustainable models inspired by nature itself.


The coronavirus pandemic has inspired us to dream of more sustainable cities, whether it is the need to free up more space for people (in order to maintain social distance on the street) or the aspiration to keep pollution at bay (which has fallen to historic lows during confinement). In this context, the idea of circular cities is resurfacing. Imagining them begins with thinking about greener cities, but merely visualising more parks and gardens is not enough: the dream is much more ambitious and involves imitating nature, taking inspiration from it to create green urban infrastructures, such as the green roofs of Berlin.

Seen from the sky, the German capital is not only green because of its parks but also because of its green roofs, which follow a tradition that began more than a century ago. One study has found that Berlin's old green roofs survive better —against the deterioration caused by sunlight and weather— than conventional flat roofs. This idea is now flourishing on Berlin's Potsdamer Platz, with 30,000 square metres dedicated to managing rainwater through a network of green roofs, urban spaces and a treatment pond.

Resisting rain showers better and making the most of their water is just one of the applications of green infrastructure. The use of vegetation on the roofs and facades of buildings also aims to improve air quality, promote biodiversity, increase the lifespan of the surface and cool urban heat islands. This commitment to lush, overflowing nature is precisely one of the characteristics of circular cities, which seek to imitate its behaviour.

The use of vegetation on the roofs and facades of buildings improves air quality, promotes biodiversity and increases the useful life of surfaces. Credit: Chris Barbalis.

Zero waste goal

The proliferation of natural spaces makes Austin, the capital of Texas, one of the most sustainable in the world. It has more than 250 parks and green areas and aims to reduce its waste by 90% by 2040. Among the initiatives to achieve this is the Austin Materials Marketplace, a platform that brings together those who generate waste that is difficult to recycle and companies that can take advantage of it. "In addition to diverting waste from landfills, these recovery activities generate significant cost savings, energy savings, and create new jobs and business opportunities," the company explains.

The model that guides these cities is inspired by the natural environment, but in a more comprehensive way: it seeks to minimize waste and pollution by reducing, recycling and reusing, but also by avoiding the overexploitation of resources. These are the principles of the so-called circular economy, an approach that seeks an alternative future to the current scientific predictions that, by 2050, we will consume three planets worth of the Earth's natural resources and generate up to 70% more waste.

Berlin and San Francisco themselves are good examples of this transition to a circular economy that is more respectful of the environment. The Californian city, a global leader in the strategy of making the most of finite resources, was the first city in the United States to legally require all its residents and companies to separate waste. Today, it reuses 80% of all waste and aims to have all rubbish produced in the city recycled or composted, with the aspiration of generating no waste at all by 2030.

Prioritizing public transport, multiplying green spaces and promoting the shared use of goods is the basis of the model of circular cities such as Songdo (South Korea). Credit: Dream Architect.

Car-free cities designed for people

These initiatives also seek to establish new models of relations among inhabitants that promote their well-being. One example is the Danish capital of Copenhagen. In addition to reducing carbon dioxide emissions by promoting the use of bicycles over cars (62% of residents use them daily to get to work), the city has shorter working hours than in much of Europe and promotes a range of free sports activities for its residents. In fact, its population is among the healthiest and happiest in the world.

This attempt to build a city without cars has also been pursued by different cities in South Korea. Songdo, located 65 kilometres from Seoul, was born in 2000 to be a global example of a smart and totally sustainable city. There, public transport is prioritized, so internal combustion cars are not allowed to circulate in the city, and schools, parks, offices and hospitals are close to residential areas. In Seoul, beyond sustainable mobility, the Sharing City Seoul initiative promotes the sharing of public and private resources with the aim of reducing waste while creating economic opportunities, as well as improving the quality of life. This initiative has, for example, promoted the recovery of abandoned buildings, the rental of suits to people before job interviews or the donation of clothes to minors.

It is expected that in the coming years the world’s cities will not stop growing. If 70% of the world's population is to live in urban areas by 2050, what will the city of the future look like? The architecture and urban planning firm Skidmore, Owings & Merrill imagines it with vegetation and pools that collect and filter rainwater for reuse. The buildings will have roof gardens to encourage small-scale agriculture and wind turbines to promote clean energy. Green modular buildings, with solar walls and windows, will be built at higher speeds and generate less waste.

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