Food Miles Versus Production Methods

What food miles measure

The term food miles describes the distance a food travels from where it is produced to where it is eaten. The idea became popular because it is easy to understand: the further something goes, the more fuel it uses. That is true as far as it goes, and distance is part of a food’s footprint. The trouble is that it is only part, and often not the biggest one.

A food’s footprint comes from several stages: growing, processing, packaging, storage, transport, shopping and cooking, as well as any waste along the way. Methods for adding these up are described in life cycle assessment. Different foods have different patterns, so the same rule does not apply across the board.

Why transport is often a smaller share

For many foods, the greenhouse gases released on the farm, from fertiliser, machinery, livestock digestion, and land cleared for farming, make up the largest share of the total. Transport by sea, by rail and even by road moves a lot of food per unit of fuel, and so tends to represent a modest share of the footprint of most products when measured per kilogram. The exact fraction varies by food, route and method, so it is better not to rely on one rule of thumb.

This is why comparing foods by distance alone can mislead. A food that travels a short way but needs heated glasshouses, or comes from a very fuel-intensive farm, may have a higher footprint than one grown in a favourable climate and shipped further. Similarly, meat and dairy often carry a high footprint at the farm gate, so choosing them locally does not necessarily make them lower-impact than plant foods shipped in, which is one reason eating less meat is often discussed as a more significant lever than shopping locally.

When distance does matter

There are real cases where transport carries more weight:

• Air freight: foods flown in, particularly fragile fresh items that must arrive quickly, tend to have a higher transport footprint because planes use far more fuel per kilogram than ships. Air-freighted produce is sometimes marked, but not always, so it can be hard to spot.
• Refrigerated transport: chilled or frozen goods need energy during the journey and in storage.
• The last leg: a car journey to the shop can add up, especially if you drive a long way to buy a small amount. Combining trips or walking, cycling or using public transport can reduce this part. A car trip to buy a single item can outweigh the whole transport chain of the groceries.
• Short shelf-life foods that spoil in transit: if transport delays cause the food to be thrown away, the lost food is part of the cost.

Production methods matter

Because the farm stage is often the biggest, how food is grown and raised deserves attention. Key factors include:

• Heated versus unheated growing: producing out-of-season crops in heated greenhouses can take considerable energy. Eating more seasonal produce, whether grown nearby or imported from a place where it is in season, generally avoids this.
• Type of food: animal products tend to need more land and feed than plant foods, which is a main reason diet choices often outweigh distance.
• Fertiliser and land use: farming methods that reduce fertiliser use or protect soil and carbon stores can lower the footprint, though results differ by farm and crop. Land cleared for farming can release stored carbon, and the topic of deforestation drivers links directly to some imported crops.
• Yield: a method that produces more food from the same land may have a lower footprint per kilogram even if it uses more inputs. This is one reason claims about organic food need care; organic farming can bring benefits for biodiversity and soil, yet yields and the climate impact per kilogram are debated, and results depend on the product and the farm.
• Storage: long storage in cold rooms uses energy too. A locally grown apple stored for many months may not have a clear advantage over one that is freshly imported.

Local still has some benefits

None of this means that buying locally is a bad idea. It can support nearby growers, keep farmland in use, give fresher food and make it easier to find out how something was produced. A farm shop or market may also have less packaging. Those are reasonable reasons to choose it. They are just different from a guarantee of a low carbon footprint.

If you are buying local, it helps to look for foods that are also in season outdoors. In that case, the two ideas reinforce each other. Out-of-season local produce that has been stored for a long time or grown under heat is a weaker choice.

A simple way to decide

Rather than relying on one rule, consider these questions in order:

1. What is the food? Plant foods generally have lower footprints than red meat and dairy.
2. Is it in season where it is grown, so it needs neither heating nor long cold storage?
3. Was it flown? If a perishable item came by air, a different choice may be lower-impact.
4. How will you get it home? Reducing car trips can matter as much as where the food was grown.
5. Will you eat all of it? Throwing away food wastes everything that went into producing it, which makes reducing waste a high priority.

These points will not give you a precise answer, and you should be sceptical of any label claiming to do so. The same caution applies to eco-label certifications, which each measure only some aspects of a food. If you are curious about how much your overall choices count, footprint calculators can offer a rough picture, but they have limits too, so treat their output as an estimate.

The practical message is to avoid fixating on distance. Eating more plants, wasting less, choosing seasonal food and being careful with air-freighted items usually make a bigger difference than the mileage printed on a label.