Cities: at the forefront of climate action

The take-away

  • Urban lifestyle can be sustainable, provided that densely populated cities contain mixed-use structures and focus on green transports like bicycles.
  • Sustainable construction that uses wood and recycled materials is still slowed by strict regulations that favour massive buildings based on concrete.

Half of the world’s population lives in cities and they create about 80% of the global CO2-emissions. In the near future, more and more people will choose an urban lifestyle adding to the urgency of shifting to more sustainable urban living.

At the same time, many political leaders are slowing climate action. Can cities take a leading role and be laboratories for a new sustainable urban lifestyle? Benedikt Boucsein, professor for urban design at Technische Universität München, thinks so. According to him, it is even necessary that cities act like pioneers in the hope that their ideas will spread.

Technologist: Why are cities so attractive for people?

Benedikt Boucsein: Cities are spaces for possibilities that promise economic and societal participation. Throughout history, they have always offered a form of equal opportunities for everyone. Centuries ago, people already left the countryside to escape local powers and despotism to find more freedom in cities. Rural exodus is still an issue nowadays, but this is not a problem per se, as long as there is a balance guided by political action.

T: Cities are responsible for about 80% of global greenhouse gas emissions. Is urban life bad for our planet?

BB: No, on the contrary. Urban life can even promote sustainable goals. For this, cities must be compact, with mixed-use structures. Density is actually an essential point for sustainable urban life. Over the last few 50 to 60 years, the urban surface per habitant has increased significantly. But the more people per space we have, the more efficient it is. One reason is that the distances get shorter, generating fewer emissions produced by mobility.

Generally, it’s not the cities that are responsible for global greenhouse gas emissions, it’s rather the way how people live in cities. If a society decides to have a resource-intensive lifestyle, urban planning alone can’t change much.

T: Through networks like C40 – a group of 90 cities all over the world – city stakeholders already try to develop more sustainable urban concepts, even if climate change isn’t on the agenda of certain political leaders. How influent can they be?

BB: I think that cities will more and more act as counterparts to national policies. In the US, we see how dozens of cities work together to develop sustainable models (like clean energy goals) – even if the government pulled out of the Paris climate treaty. If we look at the past, we see that cities always have been pioneers for change and that they can influence national policies, back to events like the Reformation or the French revolution. Cities have an advantage: states are often under the influence of big lobby groups, cities have more space for experimentation and innovation. Although there are differences: I have the impression, for example that Munich remains very car-friendly also because of the car industry which is based here.

Most importantly, though, the technologies for sustainable urban life already exist. The political process will decide on how we will use them.

T: How urgent is the situation?

BB: Cities are particularly vulnerable to the effects of climate change. Let’s take the example of extreme rain. Over the next decades, extreme rainfalls will increase significantly in many regions of the world. As urban landscapes mostly consist of asphalt, huge water masses can’t be absorbed quickly, increasing the risk of floods. Urbanists are therefore developing strategies for cities to function like “sponges”. Thanks to green roofs and more permeable surfaces, they will be able to absorb more water. Coastal cities have been building higher dykes for years.

This may, by the way, even promote biodiversity in the heart of cities. Thus, climate-related threats can also have positive effects, because they urge decision-makers to develop sustainable models.

T: Which cities are leading the way?

BB: Vancouver has launched a huge program to densify the city and to create many green spaces. In Europe, the German town of Freiburg im Breisgau is a pioneer in developing low-traffic districts where bicycles are the prioritised means of transport. In this regard, Copenhagen also has to be mentioned: almost half of all trips to or from work are made by bicycle.

Barcelona is a long-time leader in the field of smart cities. It has for example incorporated smart sensors and big data analytics into several areas like parking, trash collection, air quality and parkland irrigation. The city council has recently integrated the concept of citizen participation in order to become more sustainable. For instance, it has created platforms to allow citizens, private companies and other interested parties access to data. What is important: the city will retain ultimate ownership to avoid that multinational companies misuse the data.

T: Mobility is a big factor when we speak about sustainability. Which changes do you expect over the next decades?

BB: I think that we won’t have further major revolutions in transportation like we have seen in the past. The most important waves of the last 150 years have been: trains, tramways and underground, cars and planes. Our modern cities have been shaped to include – more or less – the infrastructures supporting these means of transportation. But I can’t see any new mode of transportation that will completely change the way we travel again. The potential arrival of drones, flying taxis and autonomous vehicles will only increase the complexity of our mobility. The question will actually be how to interconnect all these means of transportation.

In terms of sustainability, there is no better choice than the bicycle for short-distance transport. I personally hope that cities will focus much more on supporting bicycle transport in the future.

T: Talking about sustainable urban living, one must also speak about construction. What is sustainable construction?

BB: Sustainable construction mainly includes using renewable materials like wood, focus on cradle-to-cradle concepts like recycling or upcycling, concentrating on energy neutral buildings and assuring density.


T: Apart from a few media effective projects, like wooden skyscrapers, most of the new constructions that we see in cities, still are based resource-intensive materials like concrete, glass or aluminium…

BB: Absolutely. It is easier to build in an unsustainable way than vice versa. In Europe, the laws regarding construction are made for solid construction. If you wanted to use wood, you had to deliver a lot of proofs for safety, for example for fire protection. But this is about to change, many districts using wood will see the light of day over the next years.

To support innovation in construction, it could be useful to create limited areas in cities that are less regulated. Architects, engineers and urbanists could experiment with new and more sustainable ways of building without being slowed by regulations. Also, the “grey energy” (the inherent costs for transport, destruction of ecosystems etc.) of buildings made of concrete or glass is currently not reflected in the construction costs. If it was, there would be more buildings made of wood or other renewable materials.

T: Are today’s architecture students more aware of sustainability issues than the previous generation?

BB: These issues definitely take up more space during their studies than 20 years ago. However, the main motivation to study architecture remains the creative part. Students are much more interested in the plan and the design of an object than in technical issues. I think that issues of urban development need a better narrative to inspire the students.

But these things can change really quickly. When I see all these kids protesting for climate action, I am really looking forward to having them as students – and being able to respond to their, hopefully, critical approaches.

Sources: Benedikt Boucsein (Professor for Urban Design, TUM)