Saturday, October 10, 2009

Another Kink in Eating Local

Somehow I missed this article from last year. In it, two professors from Carnegie Mellon describe how despite the enormous distances that modern foods are shipped, transportation as a whole accounts for only 11% of the total greenhouse gas emissions produced by agriculture. Delivery of finished food products to retail stores accounts for only 4% of the total emissions. They conclude that "buying local" is less effective in lowering our carbon footprint than shifting from red meat and dairy to less carbon-intensive poultry, fish and veggies.

The greater efficiency of concentrating agriculture in the best locations is reflected in Jeremy's post at Ag Biodiversity. Check out his stunning maps that illustrate the global distribution of farming in 1995 versus the concentration of agriculture in only the best locations (it's not clear if this is hypothetical or actual). Like any other industry, agriculture is most efficient when located where the competitive advantages lie (e.g. good soil, weather and cheap and available labor). Unlike other industries though, I think agriculture may be an industry that we should sacrifice some efficiency in order to maintain the robustness of a distributed network. No one will starve, overthrow their government or start a war if political or natural obstacles suddenly cut them off from iPod factories on the other side of the world...

I don't have the time (or probably the qualifications!) to dig into the authors' methods to see exactly how they calculated all this, but it's a good reminder of how unintuitive complex systems can be. It's easy to suggest aesthetically-pleasing ideas such as buying local, but the devil is in the details. As James points out, there's not even close to enough land surrounding major population centers like NYC or Philly to feed all the inhabitants within a "local" number of food miles - let alone the fact that very few crops are grown in many of these regions to begin with (e.g. pretty much just dairy in upstate NY). It's often more efficient to grow crops year-round in sunny Arizona or California, or in the deep soils of the Midwest (and ship them thousands of miles) than grow them locally in cool, short summers on rocky soil.

As a big fan of New Urbanism, I'd be happy to vote for legislation that encourages dense, mixed zoning with lots of subsidized parks (including garden plots and farms) in and around cities, but that's more a statement of aesthetic preference than of effective conservation. I think we would benefit from a more clear understanding of not only the facts involving the environmental and social impacts of modern agriculture, but also our personal motivations for our beliefs.

If some sort of concentrated feed lot system turns out to be the most environmentally-friendly form of beef production, would you advocate it?


  1. Thank you for your thoughtful posts! To answer your question: "If some sort of concentrated feed lot system turns out to be the most environmentally-friendly form of beef production, would you advocate it?" If this were the case, I would advocate a diet that included very little beef.

  2. fair answer!

    I've heard a number of meat producers become very offended at the assertion that their animals are unhealthy and poorly treated, though I wouldn't want to guess what proportion of CAFOs are well and ethically managed.

    Some of my friends have gotten good deals on cowshares and stuff from local farmers. I'd be happy to eat less meat if it was higher quality and raised conscientiously.

  3. When people accuse the games industry of incorrect things, such as marketing violent games to children, I roll my eyes and get offended, too, so I have an inkling of what these guys go through. (The ESRB ratings system is in place to assist parents in keeping adult games in the hands of adults. It works, so long as parents pay attention and don't assume that all games are for children.)

    However, there are some kinds of games that I find objectionable no matter what, and I would likely change careers before working on such a game. I assume those in the cattle business are the same: those who find CAFO practices to be objectionable have left the business. So those remaining in the business, by definition, would be offended by suggestions that there is something inherently wrong with CAFO's.

  4. I've been thinking a lot about how I purchase food. My conclusion is the food that takes the least amount of resources is best. Beef is a bad use of resources.



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