I have written a number of times on the silliness of food miles and the locavore movement (here and here and here). For some reason the energy and resource intensity of foods is being judged merely on one component - transportation of the end product - which actually is only a tiny competent of food costs (and thus their resource use). Is it really more environmentally sensitive for us Phoenicians to grow our corn in the Arizona desert, where soils are unproductive and water must be imported from hundreds of miles away, rather than have it grown in the fertile soils of Iowa and trucked in?
TWO brands of olive oil, one from Australia, the other shipped 16,000 kilometres from Italy, sit on a supermarket shelf.
Most eco-friendly shoppers would reach for the Australian oil. But despite burning less fossil fuel to get here, it may not be better for the planet.
Contrary to popular belief, ''food miles'', or the distance food has travelled before we buy it, is a poor indicator of our food's total greenhouse gas emissions, or ''carbon footprint''.
More important is the way our food is farmed and produced, and how far we drive to buy it....
It turns out that stuff like economies of scale really matter
''Local food can often have a higher carbon footprint than food from afar,'' says principal researcher Brad Ridoutt.
He says even home-grown vegetables, with ''zero food miles'', do not necessarily have a smaller carbon footprint than those bought in the supermarket.
''With my veggies, I drive to Bunnings to buy fertiliser, and I go away for the weekend and forget to water them, and in the end I only harvest a few things that I can actually eat.
''By contrast, big producers, who can invest in the latest energy-efficient, water-efficient technology, and make use of all the parts of food, can be much more efficient,'' he says.
Of course, transporting food from producer to retailer still burns fossil fuels that release greenhouse gas emissions, in turn accelerating global warming. But freight emissions are only a fraction of those released during production, meaning even imported food, sustainably produced, can have a smaller carbon footprint than local alternatives.
Even the most rudimentary reading of economics should have given greenies a clue. In commodity products like most foods, prices tend to be driven down to a point that they reflect resources (and their relative scarcity) that went into the product. The cheapest foods tend to be those that use the least, and least scarce, resources in production. So buying locally grown food, which often tends to carry a price premium, should have been a flashing red light that maybe this was not the least-resource-intensive choice.