The distance that food travels from the site(s) of production to the dinner table has been a hot topic since the mid-Nineties.

But it has long been known that food miles are a much more complicated subject than the mileometer can convey, and now a paper called Food-Miles and the Relative Climate Impacts of Food Choices in the United States proposes a drastically different picture from that painted by local-food advocates.

Its authors, Christopher L. Weber and H. Scott Matthews, are two US academics, and their study undertakes an “input-output life-cycle assessment” of the greenhouse gases (GHG) associated with the food consumed by American households.

Weber and Matthews scrupulously acknowledge the methodological and statistical uncertainties in their work; care must also be taken in applying the findings to the UK and Europe. Nonetheless, their conclusions are sobering.

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Transport accounts for just 11 per cent of total GHG emissions associated with food. Production accounts for around 83 per cent. This means that: “Buying [100 per cent] local could achieve, at maximum, around a 4-5 per cent reduction in GHG emissions…”

What can would-be green eaters do? Cut down on red meat and dairy products, by far the most GHG-intensive of food groups. According to Weber and Matthews, shifting a bit less than one day’s total calories a week from those sources to “chicken/fish/eggs or a vegetable-based diet” would achieve as much as buying 100 per cent local.

There are still good reasons to buy local food. By definition, it is in season. And you are supporting a local business. But don’t think it’s a major blow in the war on climate change. You’ll do more by eating a chicken leg once a week instead of a steak – and with boiled spuds not milky, buttery mash. That's easier than restricting yourself to local produce 24/7/52.

greenkitchen@thetimes.co.uk

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