Environmental Impacts of Food: Transport

Why be an ecotarian?

Welcome to the second in our series of blog posts about how our food system impacts the environment. The whole food system from farm to table (maybe by way of a factory or two) is responsible for a fifth of the UK’s total greenhouse gas emissions, but how much does flying, shipping or driving all that produce to our shopping baskets contribute? Can we as consumers help to reduce our own impact through buying food locally? 

Forgotten journeys

When browsing the sterile environment of a supermarket, it’s easy to forget that the produce surrounding us has a life story. The system than provides consumers with an almost constant supply of the same products throughout the year is globally interconnected and heavily industrialised. The environmental costs of our food are not well reflected in pricing, which enables food manufacturing and freight businesses to reap the rewards of cheap labour and subsidised fuel. We’ve never been so disconnected from the origins of our food, so it’s unsurprising that most of us don’t picture the field where the story of that produce began, potentially thousands of kilometres across the world.

Food miles

The distance a food product travels from producer to consumer is commonly called ‘food miles’. But foods from all over the world are transported in different ways, each with a different carbon footprint. Therefore, ‘food miles’ alone cannot tell us the environmental impact of transportation unless its emissions can be quantified. The ‘global warming potential’ of each mode of transport can be calculated in kilograms of CO2 (or CO2 equivalent if you include other GHG) per tonne of food, per kilometre. When you look at these figures, shipping comes out with the lowest emissions, trains second, followed by road transport, and finally with fossil-fuel guzzling air freight having about 100 times the emissions per tonne kilometre than shipping (1).

If you look at these figures alone, you might conclude that it’s more environmentally friendly to buy all your food products shipped in from outside Europe. But the distances involved in sea transport are much larger than road transport, and because of this non-EU commodities contain much more embedded CO2 equivalent (2). In the UK, road freight makes up about 80% of transportation, and uses four times the amount of energy as rail (3). As a consumer, we don’t have much control over this, but trying to shorten the distance you buy within the UK as much as possible will help. 

This graph represents the emissions from 5 fruits and vegetables consumed in the UK, split into production and transport. Note that this is in total volume, not percentages –most of our produce comes from the UK rather than from abroad, so this graph does not indicate that UK produce is inherently more polluting! What it does show is that the carbon footprint of produce from outside Europe is dominated by transport rather than production, mainly due to air freight. In contrast, for UK produce production makes up a much larger proportion of total emissions (2).

This graph represents the emissions from 5 fruits and vegetables consumed in the UK, split into production and transport. Note that this is in total volume, not percentages –most of our produce comes from the UK rather than from abroad, so this graph does not indicate that UK produce is inherently more polluting! What it does show is that the carbon footprint of produce from outside Europe is dominated by transport rather than production, mainly due to air freight. In contrast, for UK produce production makes up a much larger proportion of total emissions (2).

High flyers

Cutting air freight out of the food chain would at first sight seem to be the most obvious way of reducing emissions. This is often dismissed however, as 50% of air freight is carried in the belly of passenger planes, meaning it does not technically put more planes in the sky (just the extra fuel from transporting more weight) (4). There are two problems with this argument. First of all, there’s the other 50%, which has a staggeringly high impact of its own (2). Secondly, it is in the interest of transport companies to encourage long-distance food transport on the routes they operate, and air freight is forecast to grow partly because of this (3). As a consumer it’s almost impossible to know which produce is shipped and which is flown, so our advice is to prioritise UK and EU food items whenever possible if you want to reduce your impact. Worryingly, cross-boundary air freight is omitted from the GHG accounts of all countries, so the impetus may not even be there to restrict growth of this sector.

Seasonality

Eating locally and seasonally are inextricably linked. For example, out of season it has been suggested buying apples shipped from New Zealand rather than stored UK apples has a lower environmental impact (1). Environmental suitability is also important: greenhouse-grown tomatoes from the UK may actually be a worse choice than the equivalent import from Spain at all times of year, because of the intensive production costs. These are unusual cases, however – buying local and seasonal is still the safest option. It’s been found, however, that up to 70% of UK city-dwellers believe they should have year-round choice of any food product (5). Arguably, reductions in emissions through decarbonisation will fail to meet the UK’s targets if not supported by behavioural changes. 

Wishful thinking

So local is better, if the produce is in season. You could probably have guessed that beforehand. But what would be the consequences if all our food was grown locally? Surprisingly, we’re already about 60% self-sufficient in food items, an increase from 30-40% in the 1930’s (1). Without a change in diet, we would need to produce a lot more fruit, along with more vegetables, sugar and animal feed. However, most of the highest quality land needed for fruit and vegetable production is already used for that purpose, so some grassland would need to be converted, displacing dairy onto lower quality land that would likely be accompanied by a decrease in yield (1). Carbon emissions from land use change would result from any conversion of woodland or other non-farmed landscapes.

And what about the producers in developing countries who trade with the UK? Wouldn’t they lose out if we became self-sufficient? This is a complex issue depending on how each particular country controls its resources, and few studies are currently available. It's known, however, that countries which allocate large amounts of resources to export production can become more vulnerable to food insecurity due to dependence on sales of one or two main products. There are also conflicts over use of land and resources; although things are improving, some countries with large food exports, such as Bolivia, still have problems with undernourishment (3). Without this trade, though, food producers would lose a significant portion of their GDP, so clearly it's irresponsible to cut ties without rethinking the way food is distributed at an intergovernmental level. As a consumer, when buying products only grown outside the continent (like tea and chocolate), Fairtrade can help to ensure benefits of global food trade reach the growers directly.

The future for localism

A 2008 study found that for the average household in the US, buying local could achieve a maximum of a 4-5% reduction in GHG emissions due to the huge relative impact of food production. In contrast, cutting out one day of red meat consumption per week would have an equivalent impact as procuring all food locally (6). This is backed up by studies in the UK, too. Eating organically is also believed to have a bigger impact, as production and import of fertilisers and pesticides has a significant footprint. If you just want to make one change, it’s more worthwhile to eat meat and dairy less often, and buy higher-quality when you do. Eating locally has many more benefits than just the reduction in emissions, however. It’s really rewarding to get to know local growers and producers, to learn more about the process that brings produce to your table, and elevates eating to an altogether more wholesome experience. It supports small scale farmers, who often use more diversified and sustainable farming practices. It keeps money in the local economy rather than dissipating it out into the pockets of, ahem, tax-dodging / exploitative multinationals. It's also been suggested that eating locally has health benefits, as fruit and vegetables lose nutrients during transportation, and over-processing for longevity also reduces nutritional value.

This whole debate is pretty complex, and we don’t have all the answers. For now, we’re going to stick to buying regionally, nationally, and continentally produced foods in that order of preference, eating seasonally as much as possible, and cutting down on our good old meat consumption. A fool-proof method is of course growing your own! We can make an impact as consumers, but ambitious regulation and good governance must also be part of the solution. We all have a say in that, too. 

Next time we'll be discussing the impacts of land use change in regions where our food is produced, and how this can effect not only local but global environmental change. Head to the links page for more info on these topics.