What you believe about food miles is probably wrong

If you want to eat sustainably then going local just feels right. Even if you can’t or won’t pay the exorbitant prices in the local farmer’s market then at least buying British or European food from your local supermarket seems to be the right sustainable choice as the food hasn’t racked up vast so called ‘food miles’ to get to your shopping basket. Unfortunately, the real picture is rather more complicated as Guardian Food Critic Jay Rayner explains in his new book, A Greedy Man in a Hungry World.

His interest in the area was prompted by his time judging US TV series Top Chef Masters in 2009 when he rather took against Las Vegas based chef Rick Moonen who claimed his Venison dish that using meat imported from New Zealand fitted with his claims of being the ‘sustainability guy’. Recently after reading an academic paper entitled Food Miles – Comparative Energy/Emissions Performance of New Zealand’s Agriculture Industry (by Caroline Saunders, Andrew Barber and Greg Taylor), he concluded that, overall, it is by no means certain that meat raised in New Zealand and shipped to the US is less sustainable than meat raised and sourced in California.

According to this exceptionally detailed study from 2006, lamb, apples and dairy produced in New Zealand and shipped to Britain have a smaller carbon footprint than the equivalent products produced in Britain. To be exact, the UK uses twice as much carbon per tonne of milk solids produced as New Zealand, and four times the amount as New Zealand for lamb.

Although the paper was produced by Kiwi academics, the main principles of the paper were peer reviewed and independently verified by Tim Benton, professor of population ecology at Leeds University who is also the “UK Champion for Global Food Security. He threw in some caveats but, he said: “The overall picture is probably true.”

Looking only at transport costs for your food is not just to miss the bigger picture; it’s to miss the picture entirely. The only way you can get some sense of the footprint of your food is by using what’s called a Life Cycle Analysis (LCA), which brings everything about the production of that item into play: the petrochemicals used in farming and in fertilisers, the energy to build tractors as well as to run them, to erect farm buildings and fences, and all of that has to be measured against yield. It’s about emissions per tonne of apples or lamb.

Using a wide sample of apple farms both in the UK and New Zealand, the researchers found that the actual weight of nitrogen fertiliser used was roughly similar in both countries (80kg per hectare in NZ to 78kg in the UK). However, in New Zealand they were getting a yield of 50 tonnes per hectare, as against 14 tonnes in Britain. Where lamb was concerned yield was higher in the UK than New Zealand, but so was nitrogen fertiliser use by a factor of more than 13. New Zealand simply has a better landscape and climate for rearing lamb and apples. Of course, as Professor Benton pointed out some of these figures may be out of date – but not by much. There are also endless arguments about what things ought to be measured and what ought not to be measured. But even if it is the most extreme example, it makes its point.

Various estimates of the carbon footprint of food transportation range from 2 to 4%, so it is a factor but certainly not the main factor in assessing the impact of your food choices. As Professor Benton put it, “If you want to wipe out all the food miles in what you eat, all you need do is swap one day’s red-meat eating a week to white meat. Not even to a vegetarian diet. Just to white meat.”

A British example is potato growing. Lincolnshire is one of the most best places in the UK to grow potatoes with its peat soil. If you tried growing potatoes nearer to London in for example the clay soils of King’s Lynn, you would get about 20% lower yield and the carbon footprint of your potatoes would be significantly bigger.

This counter-intuitive argument also applies to seasonality. A strawberry ripened beneath the winter sun of Morocco can have a smaller carbon footprint than one raised in a polytunnel at the height of the British summer.

Unfortunately we can’t draw any firm conclusions or come up any glib advice here unless you have total recall of average yield, per capita carbon emissions and other factors while doing your weekly shopping. Eating more sustainably probably means the occasional vegetarian / vegan (don’t get me started on the dairy industry!) day and preparing meals from scratch rather than relying too heavily on ready meals or take-aways.

Further reading here:

Why worrying about food miles is missing the point

Jay Rayner Explains Why Local Food Won’t Save the Planet

A Greedy Man in a Hungry World: How (almost) everything you thought you knew about food is wrong

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