With 70% of urban residents expected by 2050, cities are vital in the fight against global warming, according to scientists who paint the ideal portrait of a city “compact”green and in which one moves on foot.
Urban areas are already responsible for about 70% of global greenhouse gas emissions, according to a new report from UN climate experts (IPCC) published on Monday, April 4. With galloping urbanization in this 21st century that “will be the urban century”with nearly 7 billion urban residents by 2050, these emissions could explode if nothing is done to decarbonise existing cities and organize the ones that would otherwise emerge from the ground.
“While urbanization is a global trend often associated with rising incomes and consumption,” and thus possibly emissions, “the concentration of people and activities is an opportunity to improve resource efficiency and decarbonise on a large scale,” it emphasizes. IPCC.
Because with the same consumption, a city dweller needs less energy than his rural neighbour† “thanks to the greater density that allows for the sharing of infrastructures and services, and economies of scale”†
Based on this principle, the IPCC draws the portrait of a future low-carbon city who would be the first? “compact”that is, at a relatively high density without spreading out to infinity, limiting movements between home, work and services.
“Big cities organized around smaller communities”says Diana Reckien, of the Dutch University of Twente, who contributed to an earlier IPCC report. “Four blocks, with only small streets, a market or a park in the middle, and all services, food, doctor, hairdresser …”she told AFP.
And then, from neighborhood to neighborhood “an efficient transport system” and affordable, she argues, with Berlin as an example of recent years. The ultimate goal : “limit cars as much as possible and reduce the need for all households to own a car”†
Other key colors in this low-carbon urban palette: the green and blue†
Urban forests, trees in the streets, green roofs and facades, permeable surfaces, water points… These “green and blue infrastructure” can help cities not only absorb carbon, but also adapt to the effects of global warming.
More vegetation, for example, reduces the effects of urban heat islands, making concrete cities even more stifling during heat waves, which are increasing in number.
“Cities should combine mitigation efforts with adaptation efforts that can deliver visible local benefits”says Tadashi Matsumoto, an expert at the OECD, not involved in the report.
“If you only talk to citizens about measures to reduce emissions, they may not see it as a priority, but if you talk to them about flooding or urban heat islands, it could become their problem,” he told AFP. And thus easier to convince them.
It is important that people “Knowing why things are done and how it can improve their lives. Especially since it is often paid for by their taxes”continues Diana Reckien, who considers cities as a “Ideal place to experiment”†
The cities of the future
But to get real, these future low-carbon cities don’t all have the same challenges to face, notes the IPCC report that distinguishes three categories of urban areas.
- The “established cities” will have to replace or modernize the existing building while stimulating the evolution of modes of transport and the electrification of the urban energy system.
- The “fast growing cities” will have to plan to maintain short distances between home and work.
- And finally new or emerging citiesstarting at zero, have “unparalleled potential to become low-carbon or neutral”†
“A significant portion of the urban infrastructure that will be in place by 2050 has not yet been built”urges the IPCC, citing the potential of informal settlements that are home to more than 880 million people.
So you have to do it right the first time to avoid having to develop everything again later. “How these new cities of tomorrow will be designed and built will sustain urban energy behavior for decades, if not generations.”