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Nothing endures but change.
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 ecosystem. 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 DIFFÉRENCE
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 Michael 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 a continuous, abundant, and varied food supply for the 60 percent of the population that will live in cities twenty years from now. Ironically, the migration to cities is being driven by the “plight” of the farmer. People move to cities for economic reasons—when a city’s economy is good it pulls people to it. Droughts and floods that affect huge areas of agricultural land result in mass migration of farmers to cities in bad times. Urban farming opportunities that arise directly from the creation of vertical farms could provide jobs for these people. What could be a better outcome for displaced agricultural personnel than for them to discover that they can still plant and harvest, only now in a controlled environment? No more praying for rain or sunshine or moderate temperatures; they could save their prayers for things like winning the lottery.
Farming indoors is not a new concept; greenhouse-based hydroponic agriculture has been in existence since the 1930s. Numerous commercially viable crops such as strawberries, tomatoes, peppers, cucumbers, herbs, and a wide variety of spices have seen their way from commercial greenhouses to the world’s supermarkets in ever-increasing amounts over the last fifteen years. Most of these operations are small by comparison to traditional soil-based farms, but unlike their outdoor counterparts, these facilities can produce crops year-round. Sweden, Norway, the Netherlands, Denmark, England, Germany, New Zealand, the United States, Canada, Japan, South Korea, Australia, Mexico, Spain, and China all have thriving greenhouse industries. In addition to plants, some animal species have been commercialized by indoor farming, including freshwater fish (tilapia, trout, striped bass, catfish, carp) and a wide variety of crustaceans and mollusks (shrimp, crayfish, mussels). Cattle, horses, sheep, goats, and other large farm animals seem to fall well outside the paradigm of urban farming. However, raising fowl (chickens, ducks, geese) and even pigs is well within the capabilities of indoor farming.
Vertical farming promises to eliminate external natural forces as confounding elements in the production of food. Much of what we plant never gets a chance to grow to maturity due to adverse weather events driven by rapid climate changes that are, in turn, linked to an ever-increasing rate of CO2 emissions. Today, the United States Department of Agriculture (USDA) estimates that over 50 percent of all crops planted in the United States never reach the plate of the consumer. Droughts, floods, spoilage, and plant diseases account for most of the losses. On a worldwide basis, the situation is even worse, with nearly 70 percent of planted crops never reaching the harvest stage, succumbing—in addition to the things listed above—to attack from insect pests such as locusts and a wide variety of endemic microbial pathogens. These losses are totally avoidable, since we can now grow most of what we need to eat inside under carefully selected and well-monitored conditions that ensure an optimal yield for each species of plant and animal year-round. The choice is simple: Control everything (indoor farming) or control nothing (outdoor farming).
Today, we stand at an interesting, albeit daunting, crossroad. We continue to urbanize without incorporating the necessary skills to live sustainably, and struggle to understand enough about the damaging effects our penchant for consuming everything in sight is having on ecological processes. In this regard, science has led the way, with satellites reporting on many of the factors that contribute to our present dilemma of rapid climate change.
DO NO HARM
On a global scale, we need to emulate the physician’s credo: “Do no harm.” In this case, “do no harm” means helping the rest of life on earth to survive. In doing so, we help ourselves, as well. On the other hand, some tend to ignore the long-term consequences of their actions and opt for an immediate return on investment. In many cases, this results in different forms of encroachment into natural systems, disrupting ecosystem functions and services and eliciting a host of health problems that were clearly avoidable.
WE ALL LIVE DOWNSTREAM
One of the most pressing reasons to consider converting to urban agriculture relates to how we currently view and handle agricultural waste. In fact, we don’t handle it at all. Agricultural runoff is responsible for more ecosystem disruption than any other single kind of pollution. Most of the world’s estuaries have been so adversely affected by runoff that they no longer function as nurseries for the ocean’s marine fish, crustacea, and mollusks. That is why the United States must import more than 80 percent of its seafood from abroad. What’s more, we can do nothing about it in most instances, since floods dictate the timing and extent of the runoff events. Vertical farms would recycle their own water, thereby eliminating agricultural runoff once and for all.
WATER, WATER, EVERYWHERE
Liquid municipal waste (black water) is handled differently from solid municipal wastes, such as cardboard. Most often, in less developed countries, grey water and even black water are flushed without treatment. This greatly increases the risk of people contracting salmonella, cholera, amoebic dysentery, and other infectious diseases transmitted by fecal contamination. Instead of getting rid of the waste altogether, ideally, one would want to capture the energy in human fecal solids. A gram of feces, when incinerated, yields some 1.5 kilocalories of energy. If New York’s 8 million citizens decided to pool their fecal resource and generate electricity by incinerating it, they could realize an astounding 900 million kilowatts of electricity per year. That’s enough energy to provide electricity for many large versions of a vertical farm without tapping into the municipal grid.
Some vertical farms will be engineered as stand-alone water-regenerating facilities. They will take in safe-to-use grey water and restore it to drinking-water quality by collecting the water of transpiration using advanced dehumidifier systems. Harvesting water generated from transpiration will be possible because the entire farm will be enclosed. The resulting purified water will then be used in other vertical farms to grow commercial crops and for aquaculture.
Ultimately, any water source that emerges from the vertical farm should be drinkable, thus completely recycling it back into the community that brought it to the farm to begin with. Again, using New York City as the example, the “Big Apple” discards some 1 billion gallons of treated grey water every day into the Hudson River estuary. At a conservative five cents a gallon for industrial-quality water, it appears to be well worth the effort to recover it.
DUST TO DUST
Another major source of organic waste comes from the restaurant industry. In New York City there are more than twenty-eight thousand food service establishments, all of which produce significant quantities of “leftovers,” and the restaurateurs pay a hefty price to have it carted off. Stacks of extra-heavy-duty garbage bags bursting at the seams with the stuff sit out on the curb, sometimes for hours to days prior to collection. This allows time for cockroaches, rats, mice, and other vermin to dine al fresco at some of the finest restaurants in the Western Hemisphere. Vertical farming may allow restaurants to be paid (perhaps according to the caloric content) for this valuable commodity. Not only would an industry with a notoriously small (2–5 percent) profit margin earn additional income, it would provide raw material to be recycled through waste-to-energy schemes. Oh, and one more thing: Good-bye, vermin. In New York City, there are eighty to ninety restaurant closings each year, the vast majority of them precipitated by inspections conducted by the Department of Health. A common finding by inspectors is vermin (mouse and rat droppings, cockroaches) and generally unsanitary conditions that encourage the persistence of these unwanted diners. Eliminating significant populations of vermin by controlling the amount of restaurant waste left out on curbs and inside kitchens could encourage the development of abandoned inner-city properties for middle- and low-income housing, and without the health hazards associated with having to share space with the four- and six-legged variety of tenants.
However great the contribution of urban waste is to the destruction of terrestrial and aquatic ecosystems, it is agricultural runoff that wins the gold medal for pollution worldwide. As already alluded to, farm runoff despoils vast amounts of surface water and groundwater. Some 70 percent of all the available freshwater on earth is used for irrigation, and the resulting runoff, typically laden with leftover salts, herbicides, fungicides, pesticides, and fertilizers leached from the nutrient-depleted farmed soil, is returned to countless rivers and streams. Runoff that reaches the oceans untreated has the potential to disconnect other ecological systems through its nutrient-loading and oxygen-scavenging agrochemicals, particularly nitrates and nitrites. Estuaries and coral reefs have been the hardest hit. For example, agricultural runoff from farms in Jamaica has reduced the coral reefs in the surrounding ocean to nearly barren remnants of once abundant undersea life. This, in turn, has shut down a fishing industry that was wholly dependent on the intact coral reef for its existence. Similar results from deforestation for purposes of creating farmland have forever altered the reefs surrounding Madagascar. And a major flood in 1993 along the middle reaches of the Mississippi River left the ocean life of the Gulf of Mexico reeling for years afterward. A dead zone caused by the mobilization of nitrates left in the soil from years of agriculture along the fertile bottomland of that river system killed off an entire fishery (oysters, shrimp, fish) from Port Arthur, Louisiana, to Brownsville, Texas. Hurricane Katrina delivered the latest blow that will most likely ensure that this once productive coastal fishery remains in the dead zone for decades to come.
Vertical farming offers the possibility of greatly reducing the quantity of this nonpoint source of water pollution. The concept of sustainability will be realized through the valuing of waste as a commodity. We are now able to live for long periods of time in closed systems (e.g., the International Space Station) off the surface of the Earth, and in that instance, the concept of waste is already an outdated paradigm. Unfortunately, this goal has yet to be fully realized, even by NASA. So if we are to live continuously on the moon or Mars, then we had better learn how to do it here first. I will offer the reader my views on how we might proceed to the first vertical farm, but I have no doubt that others are working hard on the creation of a practical version of one, as well. May we benefit from everyone’s efforts and enter into the next phase of our evolution with a greater sense of security about the essentials of life itself—a safe and constant source of food and water.
To emulate the behavior of an ecosystem means to live within our means with regard to recycling energy, water, and food, and in dealing in a realistic and responsible fashion with populations. Most important, we must learn to handle the problem of waste management ecologically. In nature, there is no waste. When seen through the eyes of the ecologist, the city fails to meet even the minimum standards of the simplest of ecosystems. Everything that the city consumes comes from outside its limits: energy, water, food, dry goods. Add to that the millions to billions of dollars that are spent annually trying to get rid of waste, and you end up with a crazy-quilt system that works exactly opposite to the way we would have designed one a hundred years ago if we knew what pitfalls lay ahead.
The main premise of this book is to focus on food grown inside tall buildings within the cityscape, but if we can learn to do that, then we can also figure out what to do with the waste generated by vertical farming. Solving that problem (which would require no new technologies) would solve all the other waste-management problems, too. The bio-mimic principle has grown recently and is now the mantra for Silicon Valley and other regions of the techno-sphere. The logic system (i.e., copying what nature does best) that spawned the nanotechnology industry has led virally to a host of related new companies, and will continue to grow as we learn more about how nature has solved its problems of coping in an ever-changing environment. Howard Odum, the noted ecologist, once remarked: “Nature has all the answers. What is your question?” Mine is, how can a city bio-mimic a functional ecosystem?
Copyright © 2010, 2011, 2020 by Dickson Despommier
Foreword copyright © 2010 by Majora Carter
Afterword copyright © 2020 by Gene A. Giacomelli