Why Food Miles Are a Poor Measure of Sustainability

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, which uses 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

Buying 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, so 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.

sydney-zentz-151447

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.

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.

lotte-lohr-766

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

Balancing Different Types of Impact

With so many issues to consider, there are often trade-offs between different types of environmental impacts. The low-carbon Spanish tomatoes mentioned above, for instance, 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, but creates more acid rain and does more damage to waterways through eutrophication.

jenny-hill-202522

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!

More Meaningful Actions

Luckily, 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.

plant based

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, which saves money and reduces environmental impacts along the whole supply chain – a win-win situation.

What You Can Do

While you can make a difference by buying local food when it is in season and avoiding air-freighted food, perhaps most important of all is 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.