China is the largest polluter on the planet. Yet by 2020, the country is undertaking the creation of Liuzhou Forest City, a totally green city. Its future 30,000 inhabitants will evolve in a green and ecological conglomeration, whose trees will absorb pollution and produce about 900 tons of oxygen. If the initiative is commendable, is it reasonable to imagine the same transformation at the scale of the largest megacities on the planet? The answer is yes. Slowly, for sure, but surely. Here is a manual of how turning cities green.

As in Copenhagen, we go cycling

The Danish capital has a dream: to emit carbon no more. An ambition carried by its citizens, intrinsically ecologists. According to French newspaper Libération, in 2016, two out of three Copenhagen residents did not own a car. They prefer cycling, which has become much faster and more efficient, thanks to the city’s massive investments in cycling infrastructure. At the last count in 2015, 41% of Copenhageners went to work by bicycle. This bodes well for Copenhagen, which is aiming for a 50% rate by 2025, which would further reduce CO2 emissions per year by 10,000 to 20,000 tons per year, already reduced by 100,000 tons.

As in San Francisco, we recycle

In 2002, the Californian city launched the challenge of not sending any waste to landfill or incinerator by 2020. Many trucks are being dumped at Vacaville (a small town 1 hour drive from San Francisco) organic waste, which will end up in the form of compost, explains Le Monde. In addition to this, the sale of plastic water bottles as well as plastic bags were banned. In 2006, SF bluntly obliged all building professionals to recycle at least 65% of their debris, such as concrete, metal or wood, in certified centers, under penalty of being suspended for six months. And such measures bore fruits: in 2014, SFEnvironment reported that the city had exceeded 80% recycling.

As in Mexico, we multiply actions

In Mexico, pollution killed nearly 14,000 people in 2008, according to the Clean Air Institute. In order to stop the disaster, the Latin American city has multiplied initiatives since 2014 and the launch of the « program of climatic actions 2014-2020 » of Mayor Miguel Angel Mancera. Among these 69 actions: the construction of 55 km of bike paths combined with the deployment of 3,600 Ecobicis, vertical gardens (filmed by Reuters) and the replanting of one million trees by 2018. The last major update dates from May 2017, when Veolia signed a contract of nearly 900 million euros for an incinerator. Its heat will produce the electricity necessary to the metro of the capital, report Les Échos.

Give the plans to Stefano Boeri, the green-fingered architect

The vertical forests of Milan and Paris, it was him. The one planned for 2018 in Nanjing China and which should spread over two skyscrapers, is also because of him. Today, the Italian architect Stefano Boeri bears all the responsibility of making the Middle Kingdom a greener earth, tells Fast Company. Because after its vertical forests, Boeri is now in charge of the giant yard of the green city of Liuzhou. This initiative, which he calls “transplant”, will consists in an “ecosystem of biodiversity located at the center of a much polluted environment. It could strongly contribute to the absorption of CO2 and pollution, as well as to the production of oxygen”.

What if we only build from wood?

But not just any wood. Translucent wood and three times stronger than “traditional” wood. This patented material is due to Woodoo, the start-up created in 2016 by the French graduate in Architecture at the ENSA of Versailles and Materials Science at Harvard, Timothée Boitouzet. Since wood contains 60-90% air, “Woodoo explores the natural porosity of wood and reconstructs the structure of the plant on a molecular scale, relying exclusively on green and sustainable processes”, explains the start- up on its website. The process consists of two steps: “Selective destructuring of the wood matrix and removal of the lignin it contains” -lignin is a 35% fiber in wood that gives its rigid appearance. And “infiltration of the altered matrix of wood by compounds that polymerize in situ”. The MIT Technology Review added Timothée Boitouzet in its famous ranking of Innovators under 35.