Some of the feedback I got in response to the trial fact check column I posted a couple of weeks ago was that I should try making it a good deal more concise. I’m also interested in seeing how it flows without the conceit of the fake letter from a reader, so here’s my attempt at doing both of those things.
Is local food really better for the climate?
photo by Liz Throop
A few years ago, The Economist ran a provocative piece attacking the local, organic and fair trade food movements. As usual, it had plenty of true facts in it, but made some leaps beyond the evidence because the author was so keen to make a contrarian point.
In this post I’ll only look at one of the claims they made: that local food is no better for the climate than what’s been trucked in. Specifically: the claim that whatever harm is reduced by not shipping the food so far is outweighed by inefficiencies of the trendy small-scale food system.
One of the arguments for buying local is that typical supermarket food travels shockingly large distances from farm to table. According to the Leopold Center for Sustainable Agriculture, the average vegetable travels 1,518 miles by truck before we get to eat it. I couldn’t find an estimate for how far the average vegetable sold at a farmers’ market traveled, but we can do better: you can find out exactly how far your produce came by asking the individual traders. In my case, the average is about 100 miles – less than a tenth of the distance that its supermarket equivalent has travelled. Sounds impressive, eh?
![Men Laden With Tea, Sichuan Sheng, China [1908] Ernest H. Wilson [RESTORED]](http://farm3.static.flickr.com/2570/4079837324_9500b163ba_m.jpg)
When I think of the tomato that’s traveled 1,500 miles I think of an individual heroic fruit that’s outdone the Proclaimers in its single-minded dedication to get to me. But our transport system is more efficient than it looks, mainly because we can pack so much into one truck. On average, according to that same Leopold Center report, hauling a pound of food 1,500 miles only causes half a pound of CO2 emissions. To put this in perspective, that’s the equivalent of burning 6½ tablespoons of gasoline. Not such a huge impact, and it’s one you could easily swamp by driving a gas-guzzler to the farmers’ market.
As just one example, if the local produce is grown in a greenhouse then a surprising amount of energy will have been used to heat that greenhouse. A typical greenhouse uses 22-31 KWh per pound of tomatoes grown. At the average carbon intensity for electricity in the U.S., that translates to 29-42 pounds of CO2 emissions; about 70 times as big an impact as the shipping.
On the face of it, The Economist seems to have a point. The environmental impact of food miles is often overstated. But if we leave it at that, we miss some really crucial things.
So far, I’ve compared a relatively clean example of long-haul food—the efficiently loaded truck—with one of the most energy-intensive kinds of local food. But reality has an awkward habit of being a bit more complicated than that.
What if the long-haul food were fish shipped in from Japan, as some sushi bars round here proudly advertise? That fish has traveled much further than the average tomato, it had to be kept refrigerated on the way which itself uses a lot more energy, and to be fresh when it reaches us it had to be flown in, using far more fuel than a truck. All this for something that could have been caught locally. As a general rule, the more perishable and delicate the food, the more food miles do matter.
photo by Brian Glanz
On the local side, our veggies don’t have to come from a greenhouse burning energy to grow tomatoes because it’s either in the wrong place or out of season. When crops are naturally in season where you are, they don’t need heating, artificial light or long-haul shipping. If you’re not sure what’s in season when, you can always ask the farmer. At least you can at the market, which is one of the harder-to-quantify advantages that a local food system has over a typical supermarket.
There are all kinds of non-climate advantages to a varied local food system. They’re off-topic for this post, but they do matter and if you’d like to learn more here are some good starting points:
- Sustainweb’s Food Miles Report looks at the social costs of the industrial food system.
- Sustainable Seattle’s Local Food Multiplier Study looks at the huge benefits to your local economy when you buy local food.
After all that, what have we learned? Well, food miles alone are a much less big deal than they sound like they should be, and local food can cause surprisingly large amounts of emissions. On the other hand, the more perishable the food, the worse the impacts from transporting it, and food that’s in season locally is far less environmentally damaging than food out of season, wherever it came from.
That’s about a third shorter, which isn’t quite as short as I wanted it. I’m finding myself stuck between wanting to keep the reasoning transparent and wanting to make it shorter and snappier. I think part of the problem might be that I get attached to what I’ve already written, and part is that writing a shorter, snappier column requires a more narrowly focussed topic, so I’ll try a new topic later this week. Meanwhile, how does this one read? Does it read better this way, and/or have I taken too much out?
Good stuff Eldan! I didn’t read the first one, but I think this is a good length. I also like the added pictures, resources and changing fonts make it more eye catching. I wonder if the economist article is slanted because coming down hard on one side seems to draw more readers…
Thanks! It’s good to hear from someone who read this unprimed. Now I know it’s at least comprehensible without the bits I cut….
I’m an Economist subscriber, though I’ve been getting increasingly frustrated with them over the past few years. I feel like I know their biases quite well, and I can see a few reasons that they’d be predisposed to write a column like that:
This would also have been an easy piece for them to get wrong, because they’re not that far from the truth with it. The author just–deliberately or unconsciously–weighted one set of impacts more than the other by using best-case assumptions in some places and almost-worst-case in others. If there’s one overarching thing I want to teach people with this column, it’s how to spot that error, because it’s made over and over again, all over the place.
I like them both. What this one loses, I think are some of the philosophical aspects, and it does make the same points in condensed language. I think I like the earlier one for the ability to spin off into multiple different interesting conversations. However, I like this one for being pointed, and if you want to make a succinct argument, this is the column to go with.
It would be interesting if you could write a follow-up column on whether or not community gardens are better for the environment than large farms (organic, I presume, though there are lots of community gardeners putting non-organic pesticides, etc, on their gardens, at least round here…. maybe that’s part of the dilemma?). Maybe it’s a clear cut argument in favor of community gardens (I hope so), but what do you think?
Thanks for the feedback! I think on balance I take this as an argument for the shorter column. I do like to explain rationales more than a shorter piece allows, but I’m also kind of hoping that I can teach by repeated example, even if any one on its own doesn’t explain that much.
If we assume the exact same farming practices, then community garden vs large-scale becomes a question almost entirely of distribution. On the one hand, what I grow in my allotment has very close to zero energy consumption associated with growing and delivering it. On the other, the space that houses 40 of those plots could house more than 40 people in a building typical of its neighborhood, and that increase in density would decrease transport energy use for humans (which is far less efficient than transporting food, because we don’t take kindly to being stacked in boxes).
But then, “exact same farming practices” really doesn’t make sense as an assumption. Organic can actually be a bit misleading, as the official organic standard is kind of arbitrary about what treatments are and are not allowed – I don’t know great detail about this, but as one example copper sulphate is allowed as a pesticide, even though it’s somewhat toxic to humans and quite dangerous to fish. On the other hand, I’d like to assume that people growing food for their own consumption are careful to avoid treatments that will be harmful to them, but in reality a lot of us just aren’t well-enough educated to be sure of that. My intuition is that the difference in scale will be significant here–even if a few community gardeners are using really nasty pesticides it’s nothing compared to the mildly-nasty chemicals applied to organic crops on a large scale–but I really don’t know how to go about testing that hypothesis.
There is one part of this that could be testable enough for a future column though: the energy use cost of agricultural mechanisation vs economies of scale.
Oh, and sorry it took me a while to reply – I was in Portland hanging out with your brother.
Forgivable delay, then ;).
My suspicion is that you’re right about the “few gardeners with nasty chemicals” versus large organic farms, if only because largescale organic farmers are at the whims of the general American shopper’s focus on the appearance of produce rather than the taste – no bruises, insect holes, etc, rather than the gardener who has worked too damn hard for a particular piece of produce to let imperfections bother them.
As for the educated re:harm, there is, also, I think, an individual risk:harm decision that each gardener makes, no matter how educated – I see this in the discussions my dad and I have over permethrin, copper, dog hair, worm poop, etc…. he is far more comfortable with the risk than I am, even though (or perhaps because?) he knows far more about the toxic effects of chemicals on the body.
You’re right, though. It does seem that there are just so many variables about gardens – location, choices, opportunity costs, etc… that a direct comparison might be impossible. So yes, I’d like to see the mechanisation versus economies of scale column.
I don’t have any references to back this up, but my intuition is that the relationship between knowledge of a potential hazard and fear of it is an inverse-U curve: ignorance is bliss, but partial knowledge leads to exaggerated fear, and great familiarity can breed a sort of complacency.
I think you’re right (sorry about the delay). Anecdotally, that’s certainly true in medicine, where we fail to use checklists for things we do frequently, because of the “we know this, how can we fail?” complacency. Familiarity breeds contempt, isn’t that the saying?