DOWN ON THE FARM
Ten to twelve thousand years ago, all over the globe, humans began systematically to modify their environment by purposely domesticating parts of the natural world to meet their basic biological needs. Creating a reliable source of food and water was at the top of their list. Apparently, as if a switch had been thrown, we nearly unanimously tired of hunting and gathering. We learned how to grow crops derived from wild plants (corn, wheat, barley, rice) and to selectively breed various four-legged animals into tame versions of their wild counterparts for food, transportation, and, of course, labor. We catapulted out of the biosphere and into the technosphere, where we now find ourselves deeply embedded. Along the way, all natural systems suffered under our heavy foot of progress. It's the “progress” part of our history that we are currently having a problem with; the environmental crises of today have their roots deeply embedded in that last bit of human evolution. To understand the cumulative negative effects we have had on the natural world since we began to urbanize, we must first understand the essence of what the world was like without us in it (for glimpses of its former glory, see the BBC production Planet Earth; to see what the world might become again if we were to suddenly disappear, see Alan Weisman's book The World Without Us). By grasping the basics of what allows natural assemblages of plants and animals to organize into mutually dependent networks called ecosystems, we gain insight into how a city might be redesigned to mimic that process. It is my contention that if the built environment could behave by reflecting the integration of functions equivalent to that of an ecosystem, life would be a lot more bearable for all of us, and more economically stable, too.
The biosphere matured when terrestrial plants and animals became mutually dependent upon other each other in a harmonic symbiotic relationship. This took place over billions of years of evolutionary history. One current theory as to how all this happened, proposed first by Lynn Margulis and James Lovelock, who termed it the “Gaia hypothesis,” suggests that once primitive life on earth arose, it began to modify the environment to suit its own needs. Today, most geochemists and ecologists would agree that this theory is the most reasonable explanation for how nutrients become recycled, down to how the ambient temperature of the entire planet is maintained. Symbiosis became the norm and now defines all of nature. Virtually every living thing can be shown to be dependent (either directly or indirectly) upon all other living things, except perhaps for those microbial extremophiles that live off the scant nutrients stored in solid rock. All green plants are able to grow and reproduce using only the energy contained in sunlight, together with water and a few (at least sixteen) essential minerals they obtain from the solid substrate (mostly soil). They excrete oxygen (their gaseous waste product) into the atmosphere and store sugars and proteins in their tissues.
Herbivorous animals (humans included) take advantage of this bonanza of resources, inhaling oxygen and eating plants to fulfill nutritional requirements. Animals then routinely excrete solid and liquid wastes into the environment (future plant nutrients) and exhale carbon dioxide (our gaseous waste product) into the atmosphere, providing photosynthetic plants the opportunity to continue the cycle of life. When plants and animals die, as they all must, communities of soil-based microbes known as detritivores return the elements contained in their carcasses to the earth by the process of decay, providing a kind of natural fertilizer for the next generation of plants; it's a natural “ashes to ashes” strategy for nutrient recycling. It has existed this way for some 400 million years and will undoubtedly go on for some time to come, with or without us. The fact that it has survived for so long in the face of extraordinary environmental changes suggests strongly that it is an incredibly resilient and highly redundant system, one that is almost impossible to destroy. This augurs well for the ability of fragmented ecosystems to repair themselves if we simply learn how to keep our hands off and mind our own business.
STRENGTH IN NUMBERS
When a mixed group of plant species, all with similar tolerances for temperature and humidity, grow in a given geographic region, their very presence attracts animals of different species to coinhabit that region. The result is the eventual establishment of mutually dependent relationships, in which all the life forms in that zone, including the microbes, join to share in the flow of energy provided by the sun. This is the bare- bones definition of a functional eco system. Ecosystems are also known as biomes. Mostly, ecosystems refer to terrestrial situations, and for our purposes, I will stick to this definition. The one characteristic they all share is that primary productivity (the total mass of plants produced over a year in a given geographically defined region) is limited by the total amount of energy received and processed. In fact, the amount of available energy actually determines the very nature of each ecosystem. For example, rain forests have an abundance of sunlight and a year- round growing season, allowing all of the inhabitants that live there to prosper. In contrast, alpine forests are limited by a short growing season and lack of warmth. No ecosystem can exceed the limits of biomass production, which is strictly regulated by the total amount of incoming energy, period. In years of high productivity, energy is used to its maximum efficiency, and in lean years, largely regulated by fluctuations in weather patterns, the result is lower bioproductivity. Nature adjusts to a varying supply of calories. Cities do not follow this simple rule of nature, and therein lies the problem.
VIVE LA DIFFERENCE
Ecosystems vary from place to place, from the kinds of plants and animals found in each to the physical makeup of the landscapes. The most important features of an ecosystem are the annual temperature regimes and precipitation profiles, which vary greatly with latitude and altitude. Hence, there is a plethora of varied, vibrant, robust assemblages of life that have flourished for hundreds of thousands of years. Only recently in geological time have we been able to make any impact on their functionality. In just the last ten thousand years we have spread ourselves over the entire planet, encroaching into all terrestrial ecosystems and fragmenting most of them with our farms, grazing lands, and human settlements. We invented agriculture at least six different times across the entire globe. Food production freed us from wandering and allowed for the rise of what we have come to refer to as civilization. Unfortunately, along the way we forgot to pay attention to the processes that encouraged our own evolution—processes that are still at work today. Many ecologists, myself included, hold that unless we make peace with the natural world, we will surely lose our place in it.
THE ENEMY WITHIN
To frame the problem in an ecological perspective, in stark contrast to the natural world around us, urban centers (the “technosphere” described by William McDonough and Mi chael Braungart in Cradle to Cradle) have no apparent cutoffs regarding constraints of growth. This is especially true in the poorest countries. It's a rare situation that results in uncontrolled growth due to extreme wealth, but it happens, as well. Abu Dhabi, Dubai, and the United States routinely exceed their quotas for almost every resource, including food, water, and energy. The result of such excessive behavior has led to the problems facing us today. By defining the problem in ecological terms, we may be able to pave the way for a complete overhaul of the way we carry out our daily lives. Today, nearly 50 percent of us choose to live in cities and surrounding suburbs. These crowded urban centers rely heavily on importing food, ores, and other essential resources. If we continue to rely on harvesting resources from an environment we have created, whose production is solely dependent on using more and more fertilizers, herbicides, and pesticides, those forced ecological situations will soon fail and we will be left stranded. In fact, many agricultural regions are already failing, and others are soon to follow.
So, the real question is, can a city bio-mimic an intact ecosystem with respect to the allocation and use of essential resources and, at the same time, provide a healthy, nurturing, sustainable environment for its inhabitants? As the reader will see in what follows, I think the answer is an emphatic yes. In fact, we have no choice if we want not just to survive but to thrive. We have all the tools to do so. All we have to do is apply them creatively to address this single question. Built into this ecological survival strategy is the eventual repair of much of what we have damaged along the way to becoming seven billion strong.
HAVING IT BOTH WAYS
Repairing the environment and still having enough to eat may seem like mutually exclusive goals. If the world's population continues to increase and we need to place more and more land into agriculture, and if in doing so we are forced to cut down more forest, how can we expect the environment to heal itself? In theory, the solution is straightforward: Grow most of our food crops within specially constructed buildings located inside the city limits using methods that do not require soil. This would allow for the conversion of an equivalent amount of farmland back into whatever ecosystem was there originally, usually hardwood forest. The regrowth of the forests would eventually sequester significant amounts of carbon from the atmosphere and begin the healing process. Biodiversity would be increased, and ecosystem services, such as flood control and cleaning of the air, would be strengthened. The more urban farms there are, the larger the amount of carbon that would be converted to cellulose in the form of trees. It is that simple.
To most who hear about this scheme for the first time, it all sounds too simplistic to actually have any chance of working. It sounds downright naive and impractical. Yet, over the last ten years, the more I and my 106 bright and enthusiastic graduate students thought it through, the more reasonable the idea became. We called it “vertical farming.” It is a concept whose premise is easy to envision: Stack up “high-tech” greenhouses on top of each other and locate these “super” indoor farms inside the urban landscape, close to where most of us have chosen to live. However, I came to realize early on that making it happen will not be an easily attainable goal, and certainly not simple from an engineering and design perspective.
Although there are at present no examples of vertical farms, we know how to proceed—we can apply hydroponic and aeroponic farming methodologies in a multistory building and create the world's first vertical farms. Some parts of the world are rapidly moving toward such a scheme already, especially those countries—the Netherlands, Belgium, Germany, Iceland, New Zealand, Australia, China, Dubai, Abu Dhabi, and Japan, to name but a few—that are running short of arable farmland and have the resources to contemplate replacing the accepted traditional agricultural paradigm with something new and more efficient. Other, less affluent countries, such as Niger, Chad, Mali, Ethiopia, Darfur, and North Korea, desperately need vertical farms to rescue enormous populations from extreme hunger.
Vertical farming practiced on a large scale in urban centers holds the promise that sustainable urban life is not only possible but highly desirable and technologically achievable. With all the advances made over the last ten years in the sustainable use of resources, a city can now choose to become a functional urban equivalent to a natural ecosystem by employing high-tech versions of waste-to-energy strategies, food production, and water-recovery systems. In that way, it can process all resources that generate waste back into usable resources without further damaging the environment.
Ideally, vertical farms should be cheap to build, modular, durable, easily maintained, and safe to operate. They should also be independent of economic subsidies and outside support once they are up and running, which means they should also generate income for the owners. If these conditions are realized through an ongoing, comprehensive research program that leads to construction of efficient, productive vertical farms, urban agriculture could provide
Excerpted from The Vertical Farm: Feeding The World in the 21st Century by Dr. Dickson Despommier.
Copyright © 2010 by Dr. Dickson Despommier.
Published in 2010 by St. Martin's Press
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