The concept of “food miles” roughly measures “the distance food travels from where it is grown or raised to where it is ultimately purchased by the consumer or end user” (Pirog, 2005). The general reasoning underlying this concept goes that consumption of locally produced food or food grown within a short radius will ease carbon emission. Shortening food miles is often translated as reduction of carbon footprint by scaling down the hidden costs of energy use in food transportation (Wynen & Vanzetti, 2008) and thus help to combat global warming. While the localization of food system extends its rationalities far beyond environmental concerns, for the interest of this paper I will try to focus on the question of “how important is the notion ‘food miles’ in calculating the carbon footprint of the food system?” A wealth of literature on food system suggests, “it is not that the concept of food miles is wrong; it is just too simplistic” (Mckie, 2008, p.3). First, the emphasis on distance food traveled ignores the mode and scale of transportation; second, the exclusive aim of minimizing the distance food travels before reaching the consumer ignores the lifecycle analysis in food production phase (Wynen & Vanzetti, 2008); third, the concept of food miles solely emphasizes energy consumption in food transportation but ignores other factors, such as pesticides, labor, food storage, and capital.
The mode and scale of transport largely determine the quantity of energy used. However, the food miles concept does not address the financial and environmental costs of different transport modes and scales. According to the UK Department for Environment, Food and Rural Affairs (2005), “carbon emissions for sea transport are 15% of those for transport by road. Grams of carbon emitted per ton per kilometer (g/t/km) are 15 for sea and 98 for road, respectively. Air transport, however, emits 570 g/t/km” (as cited in Wynen & Vanzetti, 2008, p.5). Road transport also has other associated costs, such as congestion, infrastructure, accidents, and noise.
The concept of food miles also fails to fully address scale issues as well. For instance, 10 tons of grain traveling 1,000km in a 10t truck uses less energy than it does if the truck is replaced with 20 half-ton trucks.
Using distance traveled as the sole indicator of green house gas emission disregards emission of production outside of the transport sector. The green house gas emissions associated with food are dominated by the production phase. According to a working paper by Wynen & Vanzetti (2008), food production “contributes 83% of the average U.S. household’s 8.1 t CO-2e/yr footprint for food consumption. Transportation as a whole represent only 11% of life cycle GHG emissions and final delivery from producer to retail contributes only 4%” (p.3508). Food product lifecycle studies found that the most energy consumption takes place when moving the product from retailer stores to end-users. This is reasonably so because end-users often drive an empty car to the retailer stores, then drive home with few kilograms of groceries in a one-ton vehicle. The energy consumed per kilogram on the trip between “the retailer and the consumer’s home is found to be greater than the cumulative production and distribution costs to that point” (Wynen & Vanzetti, 2008, p.6).
Increased energy use in the local production and storage of goods may more than offset the energy saved in transport if, for example, GHGs are used to grow warm weather crops in cool climates. According to Van Hauwermeiren et al.’s study (2005), in which they compared emission levels from farm to retailer of tomatoes grown in Belgium for local consumption (both organic and conventional, grown outdoors; and conventional grown in greenhouse), imported from Spain by truck (conventional), and imported from Kenya by air (conventional and organic), CO2 emissions from tomatoes locally grown in greenhouses (1543g CO2/kg) are far more environmentally detrimental than emissions from tomatoes trucked from Spain (307g CO2/kg). Considering the total lifecycle of a product, local consumption does not necessarily result in lower energy use or lower carbon emissions. For instance, a study reviewed in Wynen and Vanzetti (2008), they conclude that lambs raised and consumedly locally in UK is four times more energy and emission intensive than lambs transported from New Zealand.
Over emphasis on the minimization of food traveled distance also ignores corresponding consequences. For instance, Gibbon and Bolwig (2007) gave examples of possible scenarios if the Soil Association in the UK banned airfreighted organic products from two African Countries (Kenya and Ghana) due to their extreme carbon footprint in food transportation. Among many possible outcomes, if supermarkets ban the sale of air-freighted organic produce, both exporters said they would abandon organic production and go back to selling only conventional produce (Wynen & Vanzetti, 2008). The environmental damage from such happening is far beyond the remediation the concept of food miles can possibly provide.
The concept of food miles emphasizes the use of one input (distance in its simplest form, and food transportation associated energy consumption and carbon emissions in the more sophisticated version), but ignores others, such as labor and capital. It also ignores negative externalities related to those inputs, such as the chemicals used in the production process. Weber & Matthew (2008) point out in their study “within food production, which totaled 6.8 t CO2 emission/households-yr, 3.0 t CO2 e (44%) were due to CO2 emissions, with 1.6t (23%) due to methane, 2.1 t (32%) due to nitrous oxide, and 0.1 t (1%) due to Hydro fluorocarbons (HFCs) and other industrial gases” (p.3511). Thus, a majority of food’s environmental impact is due to non-CO2 GHGs. Nitrous Oxide (NO2) emissions, mainly due to nitrogen fertilizer application, other soil management techniques, and manure management. Methane (CH4) emissions are mainly due to enteric fermentation in ruminant animals (cattle, sheep, goats) and manure management, and are thus concentrated in the red meat and dairy products (Weber & Matthew, 2008).
1. Dietary choice: according to Jane Liaw (2008), buying local is not as important as what you eat. Many authors suggest dietary shift can be a more effective means of lowering an average household’s food related climate footprint than “buying local”. Shifting less than one day per week’s worth of calories from red meet and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food.
2. Lifecycle analysis: a better approach to be aware of and understand one’s food related carbon footprint is to undertake or learn from lifecycle analysis. Such analysis should also address the impact of other pollutants ignored by the food miles concept that need to be factored into decision-making. These include those generated in the production of agricultural inputs such as chemical fertilizers, and in the production process itself, such as methane.
3. Information sharing: instead of patronizing public into certain movement, information provision can balance asymmetric knowledge between food suppliers and consumers. It informs consumers on the climate and environmental impacts of their consumptive choices
4. Pricing food associated pollutants: let market function and raise people’s awareness of their food related carbon footprint by taxing relevant pollutants. Merely patronizing public into certain movement can only paralyze healthy markets that operate on comparative advantages and result in wasteful deadweight lost.
The concept of food miles, like any other social, environmental, political movements, is not an end in and of itself. It is a strategy to achieve whatever the goal/s may be. In this case, it is to reduce our food related carbon footprint and help to combat global warming. Overemphasis on the miles food traveled can only take focus away from better alternatives and thus not only misguide advocates, but also may lead to more environmental harm than good.
Thupgon (Spring 2010)
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2. Pirog, R., & Benjamin, A. (2005). Calculating Food Miles for A Multiple Ingredient Food Product. Leopold Center for Sustainable Agriculture, 3, 1-13.
3. Born, B., & Purcell, M. (2006). Avoiding the Local Trap. Journal of Planning Education and Research, 26, 195-207.
4. Wynen, E., & Vanzetti, D. (2008). No Through Road: The Limitations of Food Miles. Asian Development Bank Institute, 1-12.
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6. Liaw, J. (2008). Mongabay.com. Retrieved Mar. 28, 2010, from Mongabay.com Website: http://news.mongabay.com/2008/0602-ucsc_liaw_food_miles.html
7. Mckie, R. (2008, March 23) How the myth of food miles hurts the planet. The Observer.
8. DeWeerdt, S. (2008). Worldwatch Institute: Vision for a Sustainable World. Retrieved Mar. 27, 2010, from Worldwatch Institute, Washington, DC. Web site: http://www.worldwatch.org/node/6064.