Urban sprawl literally defines the modern city. In fact, it has always been that way, starting with the very first urban center, Jericho (population 2,000), up to today’s champion megalopolis, Tokyo (population 34 million). As populations increased, the number of people living inside the protective walls of the earliest cities spilled out into the surrounding countryside. While the walls may have come down from today’s urban centers, encroachment is still their mantra. A well-documented example of what appears to be random growth is Atlanta, Georgia. Using Landsat photography taken from 300 miles up to record the expansion of that historic Southern city at regular intervals over the last 20 years, the isotropic radiation of Atlanta’s boundaries in many ways resembles a Petri dish inoculated with bacteria. We can all understand that this kind of growth is the result of too little planning and not enough insight into efficient use of space and resources. When no one is in charge of regulating these two things, cities grow in ways that are utterly unpredictable and without regard to optimizing resources. The result is cities that are congested, difficult to navigate and, ultimately, unsustainable in their use of resources.
Cities evolve in response to an array of forces. Most urban environments arise from humble beginnings and spread out according to politics, economics, and social pressures, carving out specialized zones for transportation, trade, recreation, housing, protection (moats and walls), and such. Many early cities routinely caught on fire or were leveled to the ground by conquering armies à la “Joshua Fit the Battle of Jericho.” Many others disappeared due to natural disasters such as earthquakes, droughts, or floods. Despite the fact that they were rebuilt many times over (Troy has had at least seven iterations according to most archeologists), in no case were they rebuilt with efficiency in mind.
Today, almost every built environment suffers from its past and continues to encourage a worsening of the social diseases of “sprawlism.” There are, of course, numerous exceptions to this paradigm. Portland, Oregon is one of the most outstanding examples of an enlightened view of city growth in the United States. Many medieval cities throughout Europe that survived into modern times also have put severe constraints on expansion—Freiburg, Germany, for example. However, most cities, regardless of location, have the unfortunate prospect of not being able to control their patterns of growth, despite the presence of city-planning departments in most of them.
What is needed, in my opinion, is a radical change in urban philosophy; one that is based on natural processes and mimics the best that nature has to offer with respect to balance. The balanced ecosystem is often referred to as a “closed loop” entity: everything the system needs to thrive—water, food, energy, et cetera—already exists within it (rather than being trucked in!) and is constantly recycled. I would encourage all city planners and developers to take a long, hard look into the ways in which ecosystems behave. It is the model for how we should be handling things like water management, energy utilization, and the recycling of waste into usable resources. In an ecosystem, assemblages of plants and animals are linked together by a common thread: the sharing of nutrients, the transfer of energy from sunlight to plants and then to animals, and the recycling of all the elements needed to ensure the survival of the next generation of those living within the boundaries of that geographically defined area. With available technologies, we can now bio-mimic an ecosystem’s best features. If cities learned to take advantage of these new technologies, then we would be well on our way to sustainability into the next millennium.
To be truly sustainable, cities must also learn to produce at least a portion of their own food. Right now, the world devotes an area the size of South America to growing crops and raising livestock. At projected rates of population growth, we would need an additional area the size of Brazil by 2050, but that much arable land does not exist. I have championed vertical farming as a start, to allow cities to produce large quantities of food crops in multistory buildings. This would avoid the need to encroach even more on the natural world to make room for farms that, in the long haul, are destined to fail due to unavoidable climate change issues.
The idea would be to take today’s indoor farming techniques—including aeroponics, hydroponics, and drip irrigation—and scale them up dramatically. The Vertical Farm Project estimates that a 30-story, 3 million-square-foot building could easily feed 10,000 city dwellers based on today’s technology. Such high-rise farms could provide a wide variety of produce and even poultry and pork. Since conditions could be controlled much more tightly than in traditional agriculture, we estimate that one acre of vertical farm space could produce as much as ten to twenty soil-based acres. If cities were suddenly able to produce their own food, the quality of life within them would improve dramatically. Fresh produce would mean better nutrition and a healthier life for all citizens. Fewer food-trucking miles would mean less air pollution. If we could establish an urban agriculture, we could achieve a certain measure of sustainability. By recycling water and converting solid wastes into usable energy, we would reduce the need to reach outside the city for these essential resources.
In short, by incorporating the best qualities of an ecosystem into the everyday functions of a city, there is no apparent upper limit to the size of a city. More important would be the improvements in quality of life for its inhabitants. Balance between our world and nature should be our prime goal. Making food production an integral feature of city life paves the way for the technical equivalent of a functional, sustainable ecosystem. Life imitates life!