Egg Miles

At the family Christmas party, my aunt and I got to talking about the food system and we spent some time talking about the environmental impacts of hauling food across the country. I’m less concerned about food miles than I used to be, in part because of a presentation I saw earlier this month at the CFANS Solution-Driven Science Symposium.

Roger A. Cady of Elanco Animal Health, who also worked for Monsanto for nine years, gave a presentation entitled Environmental Sustainability: A Benefit of Animal Productivity. Cady’s industry perspective often made me hot under the collar, but I tried to keep an open mind and appreciate the data he presented. For example, he broke down oft-cited Food and Agriculture Organization’s statistic that 18% of global greenhouse gas emissions are from animal agriculture. He showed that half that number is due to deforestation. The U.S., however, is a reforesting country, which brings our percentage down to 2.

Furthermore, Cady had a graph showing that transportation accounts for only 4% of the dairy industry’s greenhouse gas emission (the greatest amount occurs at the farm). He continued with an illustrative example comparing two vehicles. Vehicle 1 burned 70 gallons of gas in one hour, Vehicle 2—10 gallons. Both traveled 350 miles. Which is greener?

Don’t answer yet! There’s additional relevant information: Vehicle 1 had 50 passengers; Vehicle 2—4 passengers. That’s 17,500 people-miles and 250 people-miles per gallon (mpg) for Vehicle 1, compared to 1400 people-miles and 140 people-mpg for Vehicle 2.

This is a simplified example of Life Cycle Assessment, a complex and holistic method for analyzing the environmental impact of a service or product. Rather than focusing on the production process (gallons of fuel burned, miles per gallon), LCA calls for looking at the rest of the picture, including assessing the environmental impact per unit of output.

Photo credit: tiny banquet committee

So take eggs. Fill a refrigerated truck with hundreds of dozens of eggs and ship them a hundred miles to Cub or Rainbow. You’re going to get pretty good egg-miles. But if you’re a local farmer driving fifty miles to a farmer’s market with maybe twenty dozen eggs, your egg-mpg will be pitiful, according to Cady’s analysis. And then what about all of the people driving to the farmers’ market, taking home only a dozen eggs each?

Other analyses concur. Weber and Matthews of the Green Design Institute at Carnegie Mellon found that transportation from producer to retailer accounts for only 4 percent of U.S. greenhouse gas emissions (one page summary, citing World-Watch article).

Does this mean we should forget about food miles and only purchase food that’s been transported in bulk? Not necessarily, because while LCA gives a broader view than production analysis, it does so with an environmental perspective. Clearly, there are other important perspectives:

• Social: Knowing your chicken farmer, being able to visit the farm. 
• Political: Are fresh eggs equally available in all communities? 
• Food safety: Are the eggs more likely to have Salmonella?

Food miles are the BMI of the food system—that one number just doesn’t tell the whole story.