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Friday, November 2, 2007

The 100 Mile Diet: an examination of the evidence

Here is an article by Richard Reesor of our community, who shared it in our adult Sunday School class on Sunday. It has sparked lots of good reflection and discussion - we're hoping it can continue on this blog!

Richard writes:

I have noted recently many articles published in the media encouraging a movement towards local eating spawned in part by the book entitled “The 100 Mile Diet”. The introduction to the “100 Mile Diet” contains the following quotes,

“The year of eating locally began with one beautiful meal and one ugly statistic…According to the Leopold Center for Sustainable Agriculture at Iowa State University, the food we eat now typically travels between 1500 and 3000 miles from farm to plate.”

The writers go on to chronicle a year of eating food only produced within 100 miles of their Vancouver apartment. They provide an interesting collection of anecdotes describing their quest for a local diet. The message I took from the book is that this diet comes with significant sacrifice, but in the interest of building community and in the interest of the environment, society should move towards this model of a food production system. Indeed, many readers have picked up on this message, and in particular, they have picked up on the environmental message. A recent article I read makes the following claims,

“ ..in Manitoba, the average food ingredient travels 2000 km…the implications of our long-distance diet aren’t solely economic. They come with severe environmental costs…”

I am a farmer in the business of producing fresh produce and transporting it long distances, so I am interested when people write about such issues – especially when they imply these activities are unjust. Over the past couple of years I have read many similar articles making similar claims, and so I began to question my own integrity as a producer of food which is largely consumed in distant markets. (This is the case for most Canadian farmers – especially Canadian grain, oilseed , pork and beef producers.) As I thought more about the question, I decided to try to calculate the actual environmental cost of transporting food that I produced. I came up with some surprising findings. Relying on my experience with the business and a basic understanding of the science of CO2 emissions, I will share with you the following evidence:

1) A typical trip for a load of fresh fruits and vegetables arriving in Canada by truck travels 1500 miles. Typical trucks carrying produce consume 200 gallons of fuel during a trip of this length.

2) A typical load of produce traveling by truck over long distances weighs 40,000 lbs.

3) A typical serving of produce weighs 4 ounces. Therefore, the load carries 160,000 servings. At an average of 6 servings per day, this is enough produce to feed one person for 73 years, or most of a lifetime. (160,000/6/365)

4) The emissions created from combusting 200 gallons of fuel roughly equates to 1 tonne of CO2. At current prices, the cost of sequestering this carbon is about $20. This is a rough estimate of the cost of the pollution created by consuming only fruits and vegetables produced by a 1500 mile diet for a lifetime.

To summarize, if an individual in good faith took the advice of the food miles logic, and bought only fruits and vegetables produced locally rather than imported from outside Canada, in a lifetime this consumer would save 1 tonne of emissions currently valued at $20 – all things being equal.

However, all things are not equal. If this consumer decides to eat only locally produced fruits and vegetables, then we must presume that this person will eat preserved locally grown produce when fresh is not available. In fact, this is the advice contained in books like the 100 Mile Diet. The flaw in the logic of this argument is that the energy required to preserve and store vegetables to sustain us between harvests is missing from the equation. I suspect this energy is greater than the energy it takes to produce fresh vegetables and transport them from southern climates in our winter months. For example, a typical truck load of fresh fruit or vegetables is cooled and refrigerated to 3C for 3 days before it is delivered for sale to a grocery store. If we froze the same 40,000 lbs of locally produced fruits and vegetables and stored at minus 20C for an average of 6 months, sure we would save transport energy, but the energy required to freeze and store the vegetables I suspect would be far greater than the energy saved in transport. Likewise, if we preserve by canning, we must calculate the energy required to bring 40,000 lbs of produce to a rolling boil for 3 minutes and compare that with the energy consumed by transporting fresh produce as calculated above.

I would now like to take the discussion one step further. I would like to add the fact that ocean freight transport is more energy efficient than truck transport by a factor of roughly seven. Using this information, we can then extrapolate that food transported by ocean freight as far as 10,000 miles from home can be consumed and the carbon emissions created by transport are no worse than the foods we typically consume in a 1500 mile diet. Further, I will add from my experience working and living in the less developed world, I have observed that foods coming from these economies, generally are produced using significantly less energy than similar foods produced locally here in Canada. Developing world farmers are more likely to rely on human labour and animal traction than fuel burning machinery to till the soil and control weeds in their crops. Also, they are less likely to utilize energy intensive synthetic fertilizers opting to use compost and manures instead.

Moreover, the natural growing conditions of tropical climates allow the cultivation of perennial crops such as sugar cane rather than annual crops such as corn to produce similar food stuffs such as sugar much more efficiently. As an example, I am told that ethanol produced from sugar cane is 70% more energy efficient than ethanol produced from annual crops such as Canadian corn. Indeed, it is so much more efficient that Canadian ethanol producers are asking the Canadian government to erect trade barriers against Brazilian ethanol imports so Canadian producers can compete. Is it just to deny these ethanol producers and other less developed world farmers the right to sell their products to developed world consumers, especially in light of the energy and emissions savings possible from consuming their products?

There are many more issues and exceptions I could discuss. However I think I have said enough to make my point. I believe the logic in the food miles concept is fundamentally flawed. The distance from producer to consumer may be the least important consideration when considering the environmental impact of various food choices. How the food is produced (energy intensive methods vs. low input), how the food is preserved (eaten fresh or sun dried vs. canned or kept in cold storage) how the food is transported (over land or water vs. air freight) and how far the consumer travels to purchase food are more important questions.

Rather than choosing foods to eat based on the distance the food travels, I believe a more just food buying decision making rule would be to buy food with the best value - a combination of price, quality and nutrition - regardless of where it is produced. Further, I choose whenever possible to buy foods coming from the less developed world - when they are of equal or better value. I believe this to be the essence of fair trade. For example, I have no qualms at all about eating basmati rice from India - a sun dried, ocean transported product grown 10,000 miles from my home rather than potatoes grown locally. I believe that when I eat rice sourced from places like India that I am getting good value and contributing to the economic well being of less developed world farmers. Further, the analysis presented would indicate that rather than being severely damaging to the environment, the environmental impact of my buying decision is negligible at worst and may be favourable to eating a local substitute like potatoes.

I present my analysis to help initiate further discussion on this important topic. I welcome feedback and comments.

Best regards,
Richard Reesor
Stouffville, ON
crreesor@hotmail.com