Why Food Miles Are a Poor Measure of Sustainability

Food miles - air transport

You’re probably aware of the issue of food miles. Some food is transported thousands of miles between the farm and your plate, churning out pollution all the way.

Buying local food has been promoted as a way to reduce climate impacts – but does it actually work?

Let’s investigate whether buying locally produced food is always better for the environment.

Gas-Guzzling Greenhouses

When considering carbon footprints, sometimes it actually pays off to grow food in a warmer country and transport it to the UK.

For example, in the UK, tomatoes are usually grown in greenhouses heated year-round by natural gas. This means UK tomatoes use more energy than growing tomatoes in unheated Spanish greenhouses.

A study shows that even when transport by truck is accounted for, British-grown tomatoes have more than three times the carbon footprint of imported Spanish tomatoes!

greenhouse - high carbon footprint

Buying Local and in Season

Tara Garnett of the Food Climate Research Network suggests that it does generally make sense to buy local fruit and vegetables when they are in season.

Being in season means that they don’t have to be grown in heated greenhouses or kept in chilled storage for months after harvest.

For example, during the British apple season, local apples have a lower carbon footprint than those imported from New Zealand.

However, for the rest of the year, imported apples can actually have a lower carbon footprint because of the energy used to refrigerate the British apples.

While a survey by non-profit Grow-It-Yourself suggests that many of us find it hard to tell when particular fruit and vegetables are in season, guides are easy to find online.

Avoid air miles - eat in season

Avoiding Air-Freighted Food

Food miles do make a significant difference when food is transported by aeroplane. Although only 1% of food is air-freighted, aeroplanes are far more carbon-intensive than road, rail or sea transport.

Transporting food by aeroplane causes nearly 50 times more greenhouse gas emissions than transporting food the same distance by container ship!

So, while air-freighted green beans from Kenya have more than 20 times the carbon footprint of seasonal British green beans, some other imported foods such as bananas (generally transported by ship) are not particularly carbon intensive.

Unfortunately, it can be difficult to know when food has been imported by plane as it’s not always indicated on the label.

air freighted produce - bananas

Balancing Different Types of Environmental Impact

With so many issues to consider, there are often trade-offs between different types of environmental impacts.

Take the low-carbon Spanish tomatoes mentioned above for instance. These may actually contribute to water shortages in Spain as well as needing more pesticide than the British tomatoes.

Beef reared in the UK has a lower carbon footprint than beef from Brazil. However they cause acid rain and do more damage to waterways through eutrophication.

Air-freighted food can be an important source of income for workers in developing countries.

Deciding which impacts are most important is inevitably subjective. It would be easy to tie yourself in knots trying to pick the best option!

air miles - UK beef

More Meaningful Actions

There are two easier ways to make your diet more sustainable across a whole range of environmental impacts, while mostly avoiding these trade-offs: eating less meat and reducing food waste.

Meat, particularly red meat, tends to have greater environmental impacts per kilogram than plant-based alternatives.

One study showed that British diets containing meat have carbon footprints around twice that of plant-based diets.

Another study, this time on American diets, showed that vegan diets are substantially better than omnivorous diets across a whole range of environmental impacts, including land and water use, ozone layer depletion and release of toxic substances.

UK households throw away one fifth of the food they buy. Most of this waste is avoidable. Reducing waste means you have to buy less food. This saves you money and reduces environmental impacts along the whole supply chain – a win-win situation.

Food miles - plant based meal

Reducing Your Food Miles

You can make a difference by buying local food when it is in season and avoiding air-freighted food.

But it’s important to focus on more effective measures such as reducing red meat consumption and reducing food waste.

For inspiration, check out a guide to which fruit and vegetables are in season right now, some tips to reduce food waste and some yummy plant-based recipes from Deliciously Ella.