I hope it’s not too soon to be thinking about Thanksgiving.  But for those of you who like to plan ahead, there was a nifty little article in Saturday’s P-I on buying locally grown food for the annual harvest-fest.

The article was much more than the usual puff piece. I mean, sure, there was the obligatory paean or two to the scrappy local organic farmer. But what made this article extra tasty was that it in addition to the platitudes, it served up a delicious, heaping helping of…data. Mmmm, data!!

Paper shopping bag - 100Apparently, some UW researchers have tallied the greenhouse gas benefits of local, organic produce—that is, they calculated climate-warming emissions that are avoided when buying local rather than imported foods, and buying organic fruits and veggies rather than produce grown with synthetic pesticdes and fertilizers.

In every case, the more local food was better for the climate than the food shipped long distance, and the organic produce was more climate-friendly than the conventional. But the patterns were interesting, and not exactly what I would have expected.

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  • Take a look at this graph to see what I’m talking about.  For apples and potatoes, as long as they’re grown nearby there’s not a big climate difference between conventional and organic.  Organic had fewer emissions, but not drastically so.  But start importing your apples from New Zealand, or your potatoes from Idaho, and boy, the greenhouse gases start adding up.  So for apples and potatoes, the best strategy for the climate is to buy local.

    But for asparagus, the situation is reversed. Conventionally-grown asparagus from local farms was only a bit better than asparagus shipped all the way from Peru. (Peru!!!) But organically grown asparagus blew both out of the water. Apparently, “conventional” asparagus grown nearby requires a lot of energy-intensive inputs—which local organic farmers eschew, and Peru’s soils and/or climate don’t need.  In this case, the top priority (if you’re going for climate protection) is to buy organic.

    salmon-istock-112wThe biggest surprise, though, was for salmon. Eating a serving of wild fish from Alaska saves about 2 pounds of CO2 emissions, compared with imported farmed salmon from Norway.

    But a helping of salmon caught in Alaska still required huge amounts of fossil fuels.  Emissions from diesel powered fishing boats dwarfed the emissions from fertilizing and shipping produce. So where the climate’s concerned, apparently it’s better to double up on the asparagus and apples—even the ones from Peru or New Zealand—than to take a second helping of fish.

    Obviously, salmon is something more than a meal around these parts. It’s more like a sacrament. So, really, I’m not trying to make every salmon fan give up on their favorite dish. Still, if you’re curious, it’s good to know: eating low on the food chain really does seem to lessen your impacts on the climate.

    But the real lesson here may be that, when it comes to food, it’s just not always apparent what the trade-offs are.  Studies like the UW researchers have done can help, but they also require attentive and well-informed consumers.  Carbon labelling might help too; but then again, many of us have label fatigue.  (I certainly do.) But the surest thing we can do to make people aware of the climate impacts of our purchases is to put a price on carbon, so that we’re not letting anyone pollute the atmosphere for free. 

    That way, information about the climate impacts of our Thanksgiving feast would be built into the one label that  we’re sure to pay attention to:  the price tag.