Local food debate.

• Author: Wise, Carla A.
• Position: FROM READERS - Letter to the editor

Sarah DeWeerdt makes some important and often-overlooked points in the cover story of your May/June 2009 issue, "Is Local Food Better?" It is increasingly clear that many factors besides travel distance affect the environmental impact of our food choices. Farming methods and inputs, climate suitability, scale, processing, packaging, and mode of transport all matter.

However, DeWeerdt glosses over the critical hole in this debate about whether local food is a better environmental choice. As she correctly points out, all other things being equal, it is better to purchase something grown locally than the same thing grown far away. But all other things are not equal. I have yet to see a life-cycle analysis (LCA) comparing the same foods that one might eat (an apple, a head of lettuce, a pound of ground beef) from local and industrial sources. Without such comparisons, the true environmental costs of our industrial food system, and the true environmental benefits of rebuilding local food systems, cannot be accurately measured.

The problem with the Weber and Matthews study that DeWeerdt discusses is that it is based on the assumption that the only difference between locally sourced and conventionally sourced food is the distance it travels. This is clearly a flawed assumption, as the authors of the study concede. I think DeWeerdt failed to see that this renders the paper's conclusions unsupported.

Weber and Matthews conclude that dietary choices (vegetarianism vs. meat eating) are extremely important to food's carbon footprint, but food miles are not. But the greenhouse gas emissions figures used in their LCA come from industrial agriculture. Locally sourced foods are not part of this industrial-food chain. Production methods, processing, and packaging, as well as food miles, are different, so greenhouse gas emissions will differ as well. The farms where I buy local food are organic, diversified, low-input farms. How much greenhouse gases they produce was not assessed in this study. Although I have not seen the LCA of the U.K. food system by Tara Garnett, I'm guessing it has this same flaw.

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The important lessons from the Weber and Matthews study are not about local food, and were unfortunately overshadowed by their efforts to question the benefits of local food. They are, first, that industrial agriculture is a major contributor to climate change, and addressing this will be necessary to prevent a major climate crisis...