The Green Soul of the Concrete Jungle

by Apr 2, 2019Society

Dr. Robert McDonald

Dr. Robert McDonald is Lead Scientist for the Global Cities program at The Nature Conservancy. He researches the impact and dependences of cities on the natural world, and help direct the science behind much of the Conservancy’s urban conservation work. He holds a PhD in Ecology from Duke University and has published more than 50 peer-reviewed publications, and a recent book, entitled Conservation For Cities.

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On an increasingly urban planet, human society could face escalating mental health issues unless steps are taken to ensure greater access to nature and green spaces in our cities. The 21st century could be called the urban century, with 2.4 billion more people forecast to live in cities by 2050. In a recent essay in Sustainable Earth, my coauthors and I reviewed three different academic disciplines—urban economics, environmental health, and ecology—to quantify what role nature might play in this urban century. Trends in these three disciplines suggest that the urban century needs nature to succeed.

The first discipline we reviewed was urban economics, which has focused on the positive benefits to individuals, firms, and societies of life in urban settlements. One economist, Edward Glaeser, even referred to cities as mankind’s greatest invention. The major theme is that proximity—the increased potential for interaction that comes from living at higher population density—has its benefits, such as increased economic productivity, patent generation, and innovation. Aristotle famously referred to human as a social animal, by which he meant that our unique skill and love for interacting with one another is part of our species’ essence. In cities, we are creating the perfect space for social interaction. Cities could therefore be seen as quintessentially human, an expression of our deep need for social interaction.

The second discipline comes from environmental health studies of the urban health penalty. There is a clear trend toward an increased prevalence of some mental health disorders in cities. One study in Sweden of more than 4 million adults found a significant increase in the incidence of psychosis and depression among populations living at higher densities in cities than those living in more rural areas. There are multiple possible pathways by which the urban environment and its increased pace and interaction can increase stress and the prevalence of some mental disorders. Cities create a local environment with far different environmental conditions than the ones we evolved as a species to handle. Thus, in this sense, the urban environment can be shockingly inhumane, by not being in accord with our organism’s design and capacities.

The third discipline we reviewed is one that is that of urban ecologists. The central idea of this literature, coming out from the ecology and health fields, is that interacting with nature has health benefits. This occurs through multiple pathways. For example, parks and open space can help encourage recreation, which can help reduce obesity. Trees can help clean and cool the air, while natural habitats can reduce the risk of flooding. There are a growing number of studies that show a psychological benefit of interaction with nature. For instance, Cox and colleagues studied individuals in southern England, and found that neighborhoods with more than 20% forest cover had a 50% lower incidence of depression and 43% less stress.

Knowledge of the dose-response curve of nature’s effect on mental health is still imperfect. Still, given that humanity is in the midst of the fastest period of urban growth in our species history, it seems worthwhile to ask: what fraction of the world’s urbanites get enough nature now? To address this question, we examined forest cover data for 245 cities globally.

Currently, only 13% of urban dwellers live in neighborhoods with more than 20% forest cover, the amount found by Cox and colleagues that provides a protective affect against depression and stress. Despite our growing scientific knowledge of the value of nature for mental health, our urban world

So, what can be done to change this picture, to make the urban century greener? The most important step is perhaps to recognize that nature in cities is not a mere amenity, a “nice to have” thing on par with other urban amenities. Rather, nature in cities is a way to counteract the inevitable psychological downside of increased interaction in cities. Nature in cities is a way to have our cake and eat it too, to have the benefits of an urban world while still having a more humane, more natural life. Nature for urban dwellers then seems more like an essential feature of successful urban century.

We explore in our Sustainable Earth essay particular policies or programs that might help with this change in mindset, such as:

Green Prescription Programs

Doctors in New Zealand can write prescriptions for patients, requiring a certain period of time outdoors in a park or natural area. For every ten green prescriptions written, participants achieved 150 minutes of exercise, which was associated with a 20-30% reduction in all-cause mortality.


Biophilic Urban Design

A new way of designing buildings and neighborhoods tries to integrate natural elements into our cities. One commonly cited example of such a strategy is Singapore, which requires new building to replace all or more, of the nature lost at ground level by designing in space for nature on roofs or walls.


International Policy

We believe the scientific evidence suggests that interaction with nature is essential to achieving UN-Habitat and its New Urban Agenda, and policymakers should explicitly say as much. If we do not build some nature into our cities, we risk creating an inhumane, grey world for ourselves. Without nature, the urban century will fail.


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  1. excellent article of essential consequence.

  2. It seems like a missed opportunity not to have also mentioned the impacts of urbanization within the context of climate change, both positive and negative, and to reflect on the potential importance of greening and community cohesion within our urban environment to the future of our climate.

  3. the urban century and failure, the immobility is the true reflection of consumerism that at one time was the solution and good intentions of Henry Ford, his global vision, with consumerism as a key to peace, is the key to its success. His intense commitment to reduce costs led to a large number of technical and business inventions, including a franchise system that established a concessionaire in each US city. UU and Canada and in the main cities of five continents. This is summarized in this article by Mr. Edward Glaeser, who “textually” even referred to cities as the greatest invention of mankind. The main issue is that proximity, the greatest potential for interaction that comes from living in a greater density of population, has its benefits, such as the increase in economic productivity, the generation of patents and innovation, a success of consumerism and mobility that causes abundance, but at that time we never imagined until after enacting environmental laws that are not more than 20 years old in most of the countries, that the environment and oil were limited, well we have endured two world wars and important resections, in addition to achieving cities in immobility state crowded with contaminated vehicles and the third point, with the supposed benefits in disturbed mental state because our essence of transcending with higher desires after satisfying the basics is without time or possibilities in front of a brutal marketing creating enthusiasm about a false reality. We have discovered the human need to be in itself, now we must legislate it as well as the environment.
    And of course, since each human being is exclusive and unrepeatable, the forms of cities, houses and automobiles, among others, can not remain square, the square is one of the forms of the infinite forms of the universe, and humans by nature are infinite shapes.
    Now and modestly, we build and design square houses and all other forms because we realized that the need for the future to be able to exist in this human form throughout the universe, without limits.

  4. As much as cities offer a greater chance of interaction on the one hand, they also create stress and rush living style, on the other. Moreover, technology has had quite a negative effect on interaction (e.g. the TV, cell phones, internet); they are reducing physical interaction with in the City. The presence of green canopy here and there in the City can be viewed as the speed bumps on the road. They force the looker to slow down, relax and take a deep breath.

    There are a number of diseases such as tuberculosis, asthma, and so on, are curable by taking the patient into wooded areas because the oxygen content is higher; doctors prescribe that. Green colour is a relaxing colour for the eyes; ask any optometrist for confirmation. The shadow created by trees is a cooling agent; and so on. Trees stabilize soils and allow excess water to filter into the ground — the opposite of concrete. This leads to less water treatment and financial benefits. Green space offers the kids a safe place to play — instead of playing on the street under traffic danger. No wonder communities with green space have better quality of life.

    Three major players seem to influence the outcome: planners, politicians and developers. These need to be educated on the benefits of green space more than others. This expectation needs to be entrenched as part of public value and expectations. That can also help put pressure on the politicians and planners. Politicians can influence the zoning by-laws and developers would have to come up with new business models that include green space into their proposals.

    The emphasis on building skyscrapers in the City, in my opinion, is a self-defeating effort. The higher the development, the more green space there should be. But these two concepts do not mesh neatly. In my opinion, medium density development is much more manageable and healthy.

  5. Thank you dear Mr. Abe Mouaket, your intervention is very valuable in the right place. The vision that I previously exposed regarding the history and the effects of decisions then valuable and that today are a dead end, that solution that is exposed in front of the possibilities of adapting considers the last variable that you show, as beings and our two aspects of our nature, one related to the environment that says that we are the environment, that we coexist with this environment and as such we alter its existence and we also receive everything from the same environment, paradoxically in law the environment is at the same time a good furniture and property of whom we depend and obtain life, which legally nobody owns but belongs to us all without exclusivity, but on the other hand, after reaching as a human race and in the last two decades, environmental laws, a flourished a second nature or aspect of our nature that Mazlov in 1934 had already cataloged in a certain way in his scale of human needs, describes that after satisfying basic needs we have the tendency to search for the most transcendental, such as love, curiously in our gender is not yet regulated or considered this transcendental human nature … there is not even a law that cautions the stability and human transcendence that to be unsatisfied after some factor of imbalance as is the polluted environment, the time available, or the purposes that motivate the development and growth, in this case, the consumerism against the environment and the transcendental development of people.
    This reflection was carried out for some time to see me involved casually in the demand for the rights of the people behind a sewage plant in poor condition in Chile where the authority and part of the locals imagine that the river of the town is a cloaca, where they dump their human waste and garbage, while and on the other hand, friendly people who live in the most diverse jungle and the last one in such condition (Choco jungle, Pacific coast Panama-Colombia-Peru) are threatened by mega Chinese projects Americans in the area of Colombia in the name of development, who are not responsible for their waste and garbage …
    Finally, we have concluded that the jungle and the last bastions of nature are not touched and never again the supposed development (recognizing that development is quality of life) that brought us here in history can be cause for destruction, this means, Enough! No more. And if we achieve that, it means that we must go after the recovery of what has been destroyed, and that recovery must have two fronts, on the one hand from the jungle and forests with a never again and on the other hand from the city where you should start to build exclusive homes that lodge in their interior Beans with the environment of jungles and forests in gardens and vertical gardens, with their medicines, food and forms of life associated with the development of society and its cities, in this way the self-generation of solutions liberates from the vices of development that dangerously distorts the concept of quality of life, the way back to the origin, this will be reached at some point of meeting, where development and growth has no limits.

  6. excuse me all for my mistake traslation
    …that solution that is exposed to the possibilities of adapting considers the last variable that you show, as beings and our two aspects of our nature, one related to the environment that says that we are the environment, that we coexist with this environment and how such we alter their existence and we also receive everything from the same environment, paradoxically in law the environment is at the same time a movable and immovable property from which we depend and obtain life, which legally nobody owns but belongs to us all without any exclusivity , but that on the other hand, after reaching as a human race and in the last two decades, environmental laws, a second nature or aspect of our nature flourished that Mazlov in 1934…



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