Green Roofs for Urban Food Security and Environmental Sustainability
By Corinne Kisner, December 2008
URBAN AGRICULTURE
Urbanization is changing human demands and straining natural resources. In order to support this lifestyle, cities must adapt, reconsidering food sources, water supplies, the end location of their waste, the fuel supplying their electricity, and the overall environmental sustainability of densely concentrated populations. Cities consume too many resources and produce too much waste, impacting land far outside the city limits. The urban heat island effect, air and water pollution, elevated food prices and higher rates of poverty are problems endemic to cities that contribute to health concerns, economic instability, and environmental degradation. The current trend of urbanization means that without making our cities more sustainable, there is little hope for a sustainable world.
The past hundred years have seen the world’s urban population swell from 15% to 50% of the total global population, which itself has increased from 1.5 to well over 6 billion. According to the US National Research Council, by 2030 more people will be living in urban areas (4.1 billion) than in rural areas (3.1 billion) in middle and low-income countries. In fact, the population of developing countries will expand from 4.9 to 6.8 billion by 2020; ninety percent of the increase will occur in urban areas, meaning that more than half of Africa’s and Asia’s populations will live in cities. In Latin America, over 75% of the population already lives in cities.
This high concentration of people in cities has serious consequences for poverty rates and food security. The world’s urban poor tend to lack the money to purchase food and lack the land and resources to grow their own. More people living in cities with limited access to food will result in an increase in the level of urban poverty from 30 to a staggering 50% by 2020. To further exacerbate the economic hardship of city-dwellers in developing countries, the cost of feeding urban areas is high compared with rural areas. Not only must the food be collected from many small rural farmers, packaged, transported, and distributed, but postharvest food losses from inadequate preservation, as well as delays at checkpoints along poorly maintained roads increase the costs even more. “Food losses can be as high as 35 percent for perishable food products, while transportation costs can reach as high as 90 percent of the overall food marketing margin.” With such complications and insecurities, many people have turned to urban agriculture as a more dependable source of food over which they have control.
Urban agriculture, as defined by expert Luc Mougeot, is “an industry located within (intra-urban) or on the fringe (peri-urban) of a town, a city or a metropolis, which grows and raises, processes and distributes a diversity of food and non-food products, (re)using largely human and material resources, products and services found in and around that urban area, and in turn supplying human and material resources, products and services largely to that urban area.” The important and defining condition of urban agriculture, then, is not only its location but its integration within the city’s economic, social and ecological systems. Urban agriculture capitalizes on local resources, including land, water, labor, and organic waste in order to produce food for the city’s citizens. It is molded by government policies, competition over land, and urban markets and prices. In turn, urban agriculture impacts a city’s food security, ecology, health, and rate of poverty.
According to estimates by the United Nations Development Program, 800 million people partake in urban agriculture worldwide, producing 15% of the world’s food. The motives are various, with formal and informal agriculture for subsistence or supplemental food production, depending on the distance to rural farmlands and the ease of food transport to the city. The methods are also various, ranging from cooperative community gardens, private backyard plots, or public institutional gardens managed by schools, hospitals, prisons or factories. Urban agriculture is necessarily opportunistic, making use of any available plot of land on rooftops, in window boxes, in vacant lots, and beside railroads. A supply of homegrown food, and especially fresh nutritious vegetables, makes a difference in the lives of the urban poor, not only contributing to improved nutrition but allowing families to spend more of their incomes on other expenses, such as education.
The benefits of urban agriculture are numerous, spanning the economic, social, and environmental sectors. Urban agriculture contributes to the greening of cities, curbs air pollution, increases humidity, lowers temperatures, and reduces the number of trucks entering the city to deliver food. Converting organic waste to manure helps improve the ecosystem’s health in an otherwise environmentally degraded urban area. Urban agriculture provides the urban poor with a fresh source of local food that costs less by eliminating transportation costs and price increases due to middlemen. It also closes the gap between the consumer and producer of food, solving the consumer’s ignorance about the origin of their food and creating personal interest and investment in food production. Furthermore, money spent on produce grown locally and sold in farmer’s markets stays in the community, raising incomes and creating jobs. Lastly, women, the predominant urban producers, gain access to income and control over household resources and decisionmaking. These positive aspects of urban agriculture contribute directly to the United Nations’ Millennium Development Goals of eradicating extreme poverty and hunger and achieving environmental sustainability.
Despite the clear advantages of urban agriculture, there are obstacles as well. In addition to the obvious lack of space for cultivation, urban agriculture, like rural farming, is constrained by natural factors including the climate and weather. Between arid conditions and unreliable supplies of piped water for irrigation, urban producers can be restricted to the rainy season for cultivation. However, intense rainfalls sometimes damage crops, destroying months of work.
Other obstacles arise from the dense concentration of humans, plants and animals sharing air, water and soil resources. Misuse of chemical fertilizers and pesticides, as well as untreated waste, can contaminate food and water with severe environmental and public health consequences. Although problems relating to a lack of information could be easily solved with information and extension assistance, local city authorities have often responded instead by destroying food crops and evicting food producers from public lands. These policies that neglect and discourage, or even repress, informal urban agriculture harm the city’s poor. A lack of access to credit or land titles means that low-income urban producers can’t get loans and aren’t guaranteed to receive the benefits of their work. Threats from authorities may drive urban producers to use unsafe production methods. Without government support, producers are unlikely to invest in the long-term fertility of the soil or consider the benefits of organic methods.
To legitimize urban agriculture, government opinion must shift from the mindset that it is a liability and instead learn to understand the environmental, social and economic benefits. Legitimacy will allow producers to have access to land, credit, agricultural inputs, and needed services. Urban planning has so far addressed access to affordable housing, ease of public transportation, employment, and health; however, few urban planners adequately consider food security or acknowledge the importance of having a percentage of the city’s population capable of growing food, in the case that imports are unexpectedly cut off. Policies that educate and empower urban producers rather than ignore or impede them will allow for progress in public health, environmental sustainability, economic independence and food security. According to Mougeot, “Urban agriculture is most viable where it is mainstreamed into robust strategies for land use, poverty alleviation, economic development, and sound environmental management.” Governments should apply lessons from local experiences to determine policies that have multiple-stakeholder governance for sustainable urban agriculture.
A report by the International Food Policy Research Institute found that "urban agriculture complements, rather than supplants, rural supplies and imports of food and will continue to do so. Cities will continue to depend largely on rural agriculture for bulkier, less perishable foodstuffs. But urban agriculture can provide significant amounts of food at small scales and for specific items. It can generate goods valued at tens of millions of dollars in any given major city. By growing their own food, cities lower their food deficits and obtain an important source of fruits and vegetables and livestock products, including dairy. Urban agriculture provides an estimated 15 percent of all food consumed in urban areas and is likely to double that share in the next couple of decades.”
CASE STUDIES
CONCLUSION
Whether driven by the need to provide food for a city’s poor or by the desire to mitigate climate change, urban agriculture is logical and beneficial. It uses otherwise neglected spaces, such as vacant lots or roofs, which previously produced nothing for the city. The opportunistic ideology of capitalizing on every available plot of land in a city is becoming increasingly necessary as urban populations surge and cities grow crowded. Planting vegetation in cities helps to cancel the concrete jungle effect, wherein temperatures rise, polluted air isn’t filtered, and rainwater isn’t absorbed into the ground. In the future, cities will house over half of the world’s population; urban agriculture is one way to maintain a connection with the environment despite the dense living conditions humans are increasingly favoring. Bringing plants back into cities is important to remind people of the inherent value of preserving nature and of the invaluable services that the environment performs. Without a regard for that which sustains us, there is little hope for future generations’ survival.
The food security that urban agriculture provides is essential as people cannot rely on industrial farms for continuous and affordable production. Especially in cities with high rates of poverty, such as Harare, it is imperative that people maintain control of their food supply by growing their own vegetables, so as not to face scarcity and hunger if their access to imported food is unexpectedly cut off or if they can no longer afford market prices for food commodities. Community gardens foster a sense of responsibility and communal ownership over the vegetables’ success and can bring individuals together in an often isolating urban setting. With a personal stake in the long-term fertility of the land, urban farmers will have incentives to choose organic fertilizers and pesticides that will preserve their plot’s productivity. This connection to the environment’s health has positive benefits for human health as well, as it eliminates the need for the harmful chemicals that pollute water supplies. Urban agriculture allows people to eat the fruits of their labor and provides a steady, nutritious, and affordable source of food.
As developed and developing countries alike face the consequences of climate change, their governments must adapt policies to reduce greenhouse gas emissions. The current system of industrial agriculture is unsustainable and needs significant reforms. Although there is clearly an enormous number of people to feed worldwide, the high yields associated with monocropping are not worth the long-term environmental and health costs of using fossil fuels and degrading the soil with chemical inputs. Society does not place a monetary value on preserving the environment, so there are still economic incentives to produce food unsustainably. However, individuals and governments are now realizing the short-sightedness of spewing greenhouse gases into the atmosphere and have therefore begun to change their habits, seeking another way to feed the growing population. Urban agriculture allows individuals to feed themselves, rather than depend on industrial farms. It transforms the endless concrete of cities into productive green spaces. It provides a viable means for small-scale organic agriculture, producing vegetables using local resources for a local market. It combats the urban heat island effect, lowering temperatures and purifying the air city-dwellers breathe. Although there are numerous benefits to urban agriculture, it will not be widely implemented in cities across the world without government support and individual dedication. With government policies that provide financial incentives for long-term environmental conservation, urban agriculture will be one of many methods to make the lifestyle of the billions of people sharing one planet more sustainable. Urban agriculture is not only advantageous but crucial in efforts to reduce environmental stress, combat hunger and poverty by providing food security for the urban poor, and make cities more livable for future generations.
Works Cited
Argenti, Olivio. “Feeding the Cities: Food Supply and Distribution,” Achieving Urban Food and Nutrition Security in the Developing World. August 2000. 3 December 2008.
Brian Halwell, Home Grown: The Case for Local Food in a Global Market (Worldwatch Institute, 2002)
Deelstra, Tjeerd and Herbert Girardet, “Urban Agriculture and Sustainable Cities,” Trabajo Popular. 2 December 2008.
FAO, “Profitability and Sustainability of Urban and Peri-urban Agriculture,” 2007. 2 December 2008.
Garrett, James L., “Overview,” Achieving Urban Food and Nutrition Security in the Developing World. August 2000. 3 December 2008.
Mougeot, Luc, ed. Agropolis: The Social, Political and Environmental Dimensions of Urban Agriculture (London: Earthscan, 2005)
Mougeot, Luc J.A. Growing Better Cities : Urban Agriculture for Sustainable Development. Ottawa, ON, CAN: IDRC/CRDI, 2006. p 2.
Mougeot, Luc A., “The Hidden Significance of Urban Agriculture,” Achieving Urban Food and Nutrition Security in the Developing World. August 2000. 3 December 2008.