The air miles fallacy

Supermarkets are making noises at the moment about labelling food that's been flown in as such (Times), so people can make informed choices about the environmental impact of their purchases. The theory goes that food that's been flown in from abroad has a far greater carbon footprint than food produced in the UK.

The theory doesn't hold up. The time food spends on a plane contributes an absurdly tiny proportion of its carbon footprint - far less than 1%, says Tim Harford in the FT. Effectively all of the pollution occurs at the stage when it's carted around the UK on lorries or, more importantly, driven out of the supermarket in shoppers' cars. See if you're interested the original DEFRA report into the matter from 2005.

If people want to reduce the carbon footprint of their food one half of the solution is to walk (or cycle) rather than drive to the shops and carry their food home - easy in cities, harder in rural areas, not least because the supermarkets' strategy of selling us everything from t-shirts to washing machines requires huge out-of-town developments that many people can only reach by car.

The other half of the solution is to require retailers to acquire their food locally and reduce the distance it has to travel by road. However this solution is unlikely to prove popular with retailers. Acknowledging intra-UK road travel as the real food-miles pollution culprit would require them to source their produce as locally as possible, which could tip the balance of power in favour of local suppliers and obviate the retailers' cherished power of bulk purchase. If the Hexham branch of Asda was limited to sourcing its food from the immediate Northumbrian hinterland, much of its consolidated negotiating power would pass back to local producers as a reflection of far more limited buying options.   

Hence, my inner cynic tells me, the current round of apparent concern on the part of supermarkets' PR departments over the straw man that is food being flown into the country. Addressing this imaginary problem distracts us from the real one - that supermarkets are located in places that oblige many people to drive to them, and would find their leverage squeezed if each branch had to negotiate individually with local suppliers.