On 15 July EFI and the Italian government signed a Host Country Agreement to establish a new office in Rome. The office will host EFI’s new Biocities Facility, which aims to create an informed dialogue on how trees, forests and wood can rethink our cities.

Cities represent the good, the bad and the ugly of our world. They showcase some of our greatest challenges – but also offer some of our greatest opportunities for leading the transformation towards a climate-neutral and nature-positive economy.

Winston Churchill used to say that “we shape our buildings, then they shape us”. We built and shaped our first cities many thousands of years ago, and since then cities have shaped human civilization. In fact, the word civilization comes from the Latin word ‘civis’, meaning someone who lives in a city.

However, even if cities are as old as human civilization, urbanization as a megatrend is rather new. It was only during this century that, for the first time, half of the world´s population lived in urban areas. Two hundred years ago, just before the Industrial era, only 7% of the world’s population lived in cities and towns. Since then, urbanization has accelerated: every day our cities add around 200,000 more people and by 2050 more than two-thirds of the global population will live in urban areas. This also means that we still need to build 50% of the future urban fabric which will be required by then.

Infographic: Then & Now: Urban Population Worldwide | Statista

Given cities are our economic and innovation hubs, and also the major consumer of energy and resources, it is crucial that we reflect on why and how cities grow, and the consequences of such rapid urbanization for sustainable development.

Cities emerged because they are the most efficient system to self-organise ourselves in social networks that optimise our social interactions, the exchange of ideas and information, and support wealth creation based on the division of labour, specialization and innovation. They enable all this while minimising the transaction and infrastructure costs.  Cities, therefore, are the most efficient system to create social and economic capital. But what are the implications for our natural capital and for our environment, and for the relationship between humans and nature which together form the basis for sustainable development?

The visionary physicist Geoffrey West reflects about those implications in his book Scale, where he  compares the fundamental difference between how cities grow compared to biological systems. In biological systems, the amount of energy available for growth continuously decreases with increasing size until a point where growth stops. Biological systems/organisms grow sublinearly. With cities, the bigger the city, the more resources can be allocated for its socio-economic growth, and the faster it grows. The bigger the city, the more the average individual systematically owns, produces and consumes in terms of goods, resources and ideas. Cities grow superlinearly with increasing returns to scale, provided the energy and resources are available.

This explains why urbanization did not accelerate until the Industrial Revolution started, once there was access to massive and affordable fossil energy and materials. This is why England, the first country to industrialise, was also the first to reach 50% of urban population in 1850. In the USA, this only happened 60 years later. This also explains why at a global level we only reached 50% of urban population this century, after experiencing the greatest global economic acceleration ever taking place in the last 30 years. In this period of time, the urban global population has doubled but the global GDP and the global middle class have tripled. Clearly, economic growth and urbanization mutually accelerate each other. The problem is also that the environmental problems related to the existing fossil-based economy accelerate too.

After 200 years of unprecedented urbanization and economic growth based on a fossil-based economy, we have arrived at a tipping point. Our urbanized world has become too big for our planet. This is clearly exemplified by climate change, biodiversity loss and the degradation of our natural resources. We now need a new way of thinking, as a basis for a new economic paradigm for our urbanized world. A paradigm where cities, our economic and innovation hubs, take the lead in rethinking our economy and its relationship to nature in order to ensure it prospers within the renewable boundaries of our planet. This new paradigm should be based on a synergistic relationship between nature and society, economy and ecology, and rural and urban areas, in order to develop a circular bioeconomy centred around life and not consumption.

Cities need to lead this change, not only in replacing fossil energy by renewable energy but also by taking the lead in replacing non-renewable materials like plastics, steel or concrete with renewable biobased materials, and replacing grey infrastructures with green ones, making nature a basic urban infrastructure. Here, trees, forests and wood have a crucial role to play.

In Europe the use and construction of buildings represents 35% of the carbon emissions, 40% of energy consumption and 50% of all materials used. This is partly explained because two non-renewable materials dominate our urban infrastructures: steel and concrete which result in high carbon emissions. Replacing them by using wood in construction would substantially reduce the carbon footprint, because wood is the only significant construction material that is renewable and can be grown sustainably. Using wood is one of the most cost-effective ways to remove carbon dioxide from the atmosphere and store it for long periods of time.

Cities using wood in construction become carbon capture and storage infrastructures. In addition, urban forests and the strategic placements of trees around buildings decrease the energy consumption in buildings for heating and cooling. They also reduce the increasing problem of the urban heat island effect. So wood, trees and forests are called to be the backbone of climate smart cities: Biocities. I believe that the biologization of cities is essential to ensure that our urbanized world prospers in harmony with nature, for a sustainable future.

Further reading

Hurmekoski E. (2017). How can wood construction reduce environmental degradation? European Forest Institute.

Leskinen P. et al. (2018). Substitution effects of wood-based products in climate change mitigation. From Science to Policy 7. European Forest Institute. https://doi.org/10.36333/fs07

Palahí, M., et al. (2020). Investing in Nature as the true engine of our economy: A 10-point Action Plan for a Circular Bioeconomy of Wellbeing. Knowledge to Action 02, European Forest Institute. https://doi.org/10.36333/k2a02

West G. (2017). Scale. The universal laws of growth, innovation, sustainability, and the pace of life in organisms, cities, economies, and companies. New York, Penguin Press.

Main photo: ©okalinichenko/AdobeStock


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