Food Miles

Sometimes, when I come across a particularly interesting article, I try to find the research paper that it’s based on. I don’t always read the entire paper (in fact, I normally skip over huge chunks) but it’s always instructive to see the results and analysis as the original author wrote them; it’s not rare for reporters misinterpret results or selectively quote from papers, for a variety of innocent and nefarious reasons. But even if the article is excellent, I get a buzz from reading the actual research. Maybe that’s just because I’m weird, or because I occasionally hanker for my neuroscience days, but I do feel that reading papers puts you as close as you’re going to get to the scientific process.

This post and the next are both about papers I read recently. I was going to put them in a single post, but it ended up being too long, so you’ll just have to wait until tomorrow for the second one.

Food Miles

The New York Times ran an op/ed piece called Food That Travels Well about the use of ‘food miles’ when it comes to labelling and buying food. The idea is simple – you find out how far each piece of food has travelled to reach a supermarket, you print that on the packaging, and let consumers decide whether they want to buy it. The unspoken but obvious assumption here is that the more miles food has travelled, the more carbon dioxide has been released, and the worse it is for the environment. Thus, you should favour local produce over foreign produce, even if it costs more, because it’s better for the environment.

When I first heard about food miles, I immediately thought there was something fishy about it. Apart from smacking of protectionism, it ignored a whole host of factors, such as the means of transport. If you’re (say) loading ten thousand tonnes of potatoes on a ship from America to the UK, will that release more carbon dioxide, per potato, than driving five tonnes of potatoes on a truck from one end of a county to another? The answer is, I have no idea. But it’s clear that some forms of transport are more polluting than others, and just looking at the physical distance covered is a poor way of measuring environmental impact.

The op/ed piece was about research conducted by Lincoln University in New Zealand, which went way beyond my transport concerns by doing a life cycle analysis on the transport and production of food. In other words, they looked at:

…Water use, harvesting techniques, fertilizer outlays, renewable energy applications, means of transportation (and the kind of fuel used), the amount of carbon dioxide absorbed during photosynthesis, disposal of packaging, storage procedures and dozens of other cultivation inputs.

What did they find?

…Lamb raised on New Zealand’s clover-choked pastures and shipped 11,000 miles by boat to Britain produced 1,520 pounds of carbon dioxide emissions per ton while British lamb produced 6,280 pounds of carbon dioxide per ton, in part because poorer British pastures force farmers to use feed. In other words, it is four times more energy-efficient for Londoners to buy lamb imported from the other side of the world than to buy it from a producer in their backyard. Similar figures were found for dairy products and fruit.

How similar? Referring to the original paper, Food Miles – Comparative Energy/Emissions Performance of New Zealand’s Agriculture Industry (PDF) by Saunders, Barber and Taylor:

The UK uses twice as much energy per tonne of milk solids produced than NZ, even including the energy associated with transport from NZ to the UK This reflects the less intensive production system in NZ than the UK, with lower inputs including energy…

NZ is also more energy efficient in producing and delivering apples to the UK market than the UK is. NZ energy costs for production are a third of those in the UK. Even when transport is added NZ energy costs are approximately 60 per cent of those in the UK. Consequentially the CO2 emissions per tonne of apples produced are also higher in the UK than in NZ, reflecting the higher energy use but also the lower emissions from NZ electricity generation.

This shouldn’t be surprising. Most foods grow better in some parts of the world than others; considerably better. Looking at the raw data, the UK uses vastly greater quantities of nitrogen fertiliser than NZ, partly due to those clover fields mentioned earlier. When it comes to dairy production, the UK has to bring in comparatively huge amounts of cereals and concentrates to feed animals, whereas in NZ, animals can graze outside all year round. All of this releases more carbon dioxide and pollution.

The point is, no matter what your priorities are, you can’t make a sensible decision on food purchases based solely on the distance food has travelled to get to your plate. There are good reasons for why someone might want to favour local produce over foreign produce. The environment is not necessarily one of them.

7 Replies to “Food Miles”

  1. It also seems to me that transporting ice cream, for instance, is going to have a higher carbon-cost than transporting rice or oranges or any other room-temperature items because of the extra energy needed for refrigeration.

    But yes, I agree that there is something flawed in the “food miles” idea.

  2. Delighted to see this getting picked up – good post. There’s some other interesting stuff on this out there – IIRC, the British produce onions very effectively, but we should import tomatoes and lettuce from Spain,r something like that.

    Also see here:

    Brian is right to raise the issue of refrigeration – all those who witter about shipping, rather than airfreighting, food tend to have omitted to calculate the amount of energy required to refrigerate food to keep it fresh on the long sea journey…


  3. Excellent post! I’m resisting adding a rant here about OrganicTM food and its environmental impact. But simply limiting myself to carbon footprint OrganicTM food can have a greater impact than non-organic alternatives (chicken being an example).

  4. Interesting thoughts on a topical subject. Another consideration is what the consumer does next to the food. Does it get eaten immediately or frozen for months; how is it cooked; how much product makes up a meal – this may be different for different people – an extra potato on the plate means you are one potato nearer to revisiting the market – in turn this has health, fitness, transport and diet implications, which leads to pressures on the health service and further congestion..I think I’ll stop now!

  5. Very interesting post!

    I read a piece from Graham Harvey (on the Guardian website) which suggested that the energy-intensiveness of British lamb and dairy farming is largely a result of the EU’s Common Agricultural Policy. This subsidises the overproduction of grain, half of which is used as animal feed. According to Harvey, it is this, rather than the quality of English grass, that drives farmers to keep their livestock in sheds, raising their carbon footprint.

    Here’s the article:

    It’s no scientific paper, and he clearly has his axes to grind, but I’d be interested to know more.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s