One current fad is to source all one's food locally so as to reduce one's "carbon footprint". The suggestion is that by reducing all those "food miles" one reduces the negative impact of shopping on the environment.
Is it true? And if so by how much?
The findings of two researchers suggest that the answer to the latter is "not much". According to Christopher L Weber and Scott H Matthews in their paper Food-Miles and the Relative Climate Impacts of Food Choices in the United States,
Despite significant recent public concern and media attention to theSo instead of buying locally, we could just eat like Catholics and make a far larger contribution to reducing carbon emissions than by buying locally.
environmental impacts of food, few studies in the United States have
systematically compared the life-cycle greenhouse gas (GHG) emissions associated
with food production against long-distance distribution, aka "food-miles." We
find that although food is transported long distances in general (1640 km
delivery and 6760 km life-cycle supply chain on average) the GHG emissions
associated with food are dominated by the production phase, contributing 83% of
the average U.S. household's 8.1 t CO2e/yr footprint for food consumption.
Transportation as a whole represents only 11% of life-cycle GHG emissions, and
final delivery from producer to retail contributes only 4%. Different food
groups exhibit a large range in GHG-intensity; on average, red meat is around
150% more GHG-intensive than chicken or fish. Thus, we suggest that 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 meat and dairy products to chicken, fish,
eggs, or a vegetable-based diet achieves more GHG reduction than buying all
locally sourced food.
In fact, Weber and Matthews' findings are only half the story. The real measure should be the total environmental cost of local production verses most-efficient production. The point of trade, after all, is that is allows products to be produced where the production is most efficient. As Art Carden explains,
One of the "key elements" of economics is that trade creates wealth. Wealth is
whatever people value, but trade allows us to produce either more material goods
with the same resources or the same material goods with fewer resources. While
it does not profit a man to gain the world but lose his soul, trade increases
our ability to produce goods and services and therefore increases our range of
By producing food where it is most efficient to do so (i.e. where more foodstuff is produced per acre, per man-hour, per tonne of water, per combine harvester etc.), we actually reduce agriculture's impact upon the planet. Taking just carbon emissions for now, if 83% of food emissions result from the production of food and only 11% from transport from the farm via the factory to the shop, it is clear that improving the efficiency of production is a more effective means of reducing carbon emissions than buying food that is produced locally and less efficiently.
But why must local production be less efficient? There is no reason that it should (someone must live locally to the most efficient production, after all) but because greater efficiency equates to lower costs, the easiest way to measure the efficiency of production is to look at the price label. If it is worth importing goods from foreign countries it must be because they produce the goods more efficiently.
I realise that locavores are motivated by more than just the environment, of course. Mrs. Polemic has a whole Good Life thing going on! Carden himself notes that home-produced or locally-produced products may win on quality (though often the reason that commercially-produced food tastes so bland is the fault of Government regulation).
However, the environmental motivation for eating locally produced food is one of the main reasons many locavores advocate it, yet it may in fact be increasing carbon emissions.
So the next time you deliberately buy locally sourced produce, you can console yourself with the thought that though a Third World farmer has not enjoyed your patronage today, it doesn't matter, as his farm has probably been swallowed by the desert anyway!