Big cities can only go one way: towards massive re-forestation. This is how environmental and social sustainability is nurtured

“Access to green spaces is always a matter of environmental justice”, says Elizabeth Diller, the architect who revolutionized the idea of ​​urban and landscape regeneration.

For Diller, the restoration of the city space is above all a social matter. An openly political commitment that architects should assume spontaneously. Because it is in the conquest of every small strip of common space within large cities that a battle against collective inertia is first fought. The challenges of climate change are, yes, beyond the reach of individuals, but in need of unanimous advocacy. In short: the recovery project of the New York High Line was born from activism and civil participation, to then become a starting point, a cultural input that has definitively changed the idea of ​​urban regeneration.

Also according to Liz Diller, the pivot around which the success of the New York High Line revolves – or that of the Zaryadye park in Moscow and its one million visitors in the first month of opening – is greenery. Not the landscape design as an aesthetic definition of an artificial place, but the relaunch of spontaneous nature, of the re-invasion of weeds and local flora, which obviously is then populated by wild animals, from insects to small mammals. Useful for the restoration of a virtuous balance in which the boundaries between civil and non-civil become useless.

The fluidity between greenery and the ‘mineralized’ environment is in fact the great climatic and economic challenge of metropolitan areas. For citizens to feel at ease and to be able to truly exploit public space, urban nature must be an integrated, free system that is co-inhabited by humans, animals and plants. It is the exit from the anthropocentric mindset necessary to imagine a healthier planet.


Cities are one of the first places for the green transition. The solutions aim to change the urban paradigm thanks to, it seems incredible, massive reforestation. The municipality of New York is planning to put in place one million trees, not to make the landscape pleasant, but to obtain significant savings in the climatic management of buildings, in public health, in the commercial enhancement of spaces.

The Global Commission on the economy and climate warns that cities that do not adhere to an idea of ​​green growth are destined to become depopulated and to suffer economic decline. The green transition of large urban centers involves the regeneration of greenery within large run-down areas, also and above all in order to remedy an urbanization that is dangerously unhealthy and unable to generate benefits.

From this point of view, China is leading the way. Going from holding a world pollution record to playing the role of leader of urban regeneration means first of all thinking big and investing a lot of money. Two qualities on which the Asian giant is also aiming to re-establish an idea of ​​collective well-being.“While on the one hand it was neglected during the capitalist boom years, on the other it remains a priority political diktat” explains Aldo Cibic, author of a social and territorial reclamation project in Shanghai, together with Tongji University. The restoration of landscapes means making the whole population participate in a widespread quality of life, synonymous with well-being and long-term strategies. “The population is involved, although it is not easy to imagine China as a democratic place. And participation becomes co-planning much more easily than in more democratic countries”, concludes Cibic. The pandemic has strengthened research efforts, which focus on the evolution of these energy-eating dinosaurs. Forestry, the creation of the famous sponge parks, and the development of urban agricultural policies transform cities into producers of resources. Green saves energy, cleans the air, improves air quality.

The ideal of a distributed quality of life is part of the green transitions of all megacities. Regenerating is expensive and the risk of playing a new social battle on the cost of sustainability is not so remote. One of the most frequently asked questions that Stefano Boeri is asked about ten years after the inauguration of the Vertical Forest is still: how much does it cost per square meter? Not a trivial question. Regenerating costs a lot. Planting small forests on the facades of skyscrapers has prohibitive prices. “But the investments made were used to experiment with a model and then make it reproducible” specifies the architect in the Rai docuseries Lessons on the end of the world. “At the moment we are building vertical forests which cost 1250 euros per square meter”. It is necessary to understand the functionality of the green, measure them, transform them into surplus value.

However, the war between green capitalism and the more fragile economies is a reality. The major regenerative projects of the Milanese airports will displace hundreds of millions of euros and contribute to the risk of gentrification. 180 million euros are the investment only for the Porta Romana area, the future Olympic Village promoted by Prada, Coima and the French Covivio. The solution, according to the director of the Bocconi Green Economy Observatory Davide Croci, is: “the consultation of public and private institutions on a common agenda”.

And, as Liz Diller recalls, the ethical commitment of architects. All that remains is to hope that the Diller Scofidio + Renfro studio will win the competition for the new project.


Cover photo, Smart Forest City, a project by Stefano Boeri Architetti for a self-sufficient settlement in Cancun, Mexico. Credit The Big Picture.