Food miles and the carbon footprint of food production


It was back in 2000 that I first gained an interest in food miles. That interest was reawakened in the last few weeks with a focus on salmon farmers claims regarding carbon footprint and food miles. Recent fears, even last week at the United Nations, and the growing awareness about the reality of climate change and global warming is a stark reminder that we need to rethink many of our “globalised” expectations regarding food supply. But food movement in not only a phenomenon of our times. North Africa was the bread basket of the Roman Empire and Francis Drake the
explorer, imported potatoes and sugar into Britain from South America in the late 1500s.

The first Food Miles report by Professor Tim Lang entitled “The dangers of long-distance food transport” was published in 1994 and this illustrated the environmental and social implications of the rapid escalation in the distance our food was travelling “from plough to plate”. By one measure – that of output from the farmers field – the industrialisation of farming has been a triumph of technology. But the cost efficiency of production has led to underlying problems. Topsoil is being eroded, soil productivity has fallen and there is a serious loss of the soil’s organic structure. Many ancient civilisations have collapsed because they degraded their topsoil which often led to accelerated erosion and loss of moisture retention. More recently demands to grow crops in arid areas has resulted in serious depletion of ground water resources on which subsistence farmers relied. This degradation of the natural capital (natural capital can be defined as the world’s stock of natural assets which include geology, soil, air, water and all living things) that is the foundation of sustainable farming is not effectively costed in our food for sale in the supermarket. Additional changes due to monoculture practices include loss of biodiversity, increase in pesticide and fungicide use and progressive resistance to the armoury of chemicals we rely on. Monocultures’ chemical dependence requires enormous amounts of energy intensive fertilisers to make up for the loss of soil biota, other plants and manure,
which can provide crops with essential nutrients more akin to natural systems. All these interventions increase the carbon footprint of food production.

Food miles is a measure of the distance food or final food ingredients are transported from the point of production until they reach the consumer. Food miles is one factor used when assessing a major environmental impact of food, namely the fossil fuel contribution to world warming. Some believe that an increase in the distance food travels is a product of the globalisation of trade generally. This in turn has driven the focus of food supply sources into fewer, larger districts; drastic changes in delivery patterns; the increase in processed and packaged foods; and consequent loss of local suppliers being replaced by dependence on large supermarkets. These factors make up a small part of the greenhouse gas emissions created by growing and supplying food, its carbon footprint; 83% of overall emissions of CO2 are in production phases.

Carbon footprints and food miles. A carbon footprint is a measure of how much carbon, largely in the form of fossil fuels, is used in the production and transportation of a product. Some of the food harvested in the UK is sent abroad to
be processed before being returned to the UK, so this has a higher carbon footprint. Food miles are often used to refer to the total distance food has travelled before it is sold. Several studies have compared emissions over the entire food
cycle, including production, consumption, and transport. These include estimates of food-related emissions of greenhouse gas ‘up to the farm gate’ versus ‘beyond the farm gate’. In the UK, for example, agricultural-related emissions may account for approximately 40% of the overall food chain (including retail, packaging, fertilizer
manufacture, and other factors), whereas greenhouse gases emitted in transport account for around 12% of overall food-chain emissions.

Today we are able to head down to the supermarket and other local stores and purchase a vast array of foods from all over the world, no longer restricted by local environmental factors and/or the seasonality of a product: flowers from Africa, fruit from Europe and the southern hemisphere in our winter, snacks from Asia and spices from South America. Today retailers can source food from wherever it is cheapest around the globe at the touch of a computer key. Air freight generates 50 times more carbon dioxide, CO2, than sea shipping per tonne of food transported.
But shipping by sea container is slow, and in our increasing demand for fresh perishable food, this is more frequently being shipped by faster—and more polluting —means.

In order to transport food long distances, much of it is picked while still unripe and then exposed to ethylene for example to “ripen” it after transport, or it is highly processed in factories using preservatives, irradiation, and other means to keep it stable for transport and sale.

By emitting nitrous oxides and particulates in addition to carbon dioxide in combustion food transportation causes air pollution. Poor air quality in urban areas is considered to be the most dangerous environmental threat caused by transportation. Highway vehicles, marine engines, trains and planes are the main causes of pollution which affects air quality causing damage to human health.

The concept of “food miles” has been criticised, and food miles are not always correlated with carbon footprint which is the climate change factor of food production. For comparison, the proportion of total energy used in home food preparation is 26% and in food processing is 29%, far greater than transportation. It is often claimed an ‘average’ food product travels 1500 miles before reaching the consumer. But mileage does not represent where our food is grown or manufactured, and how it is processed, stored and transported. For example take UK-grown green beans. Yes, they do not journey as far as those same beans grown in Kenya. But the ability to grow them here relies on fossil-fuel farm machinery and manufactured fertilisers, potentially representing a higher environmental impact than the flown-in kind, farmed using much less energy. Further, a study as long ago as 1998 demonstrated that Swedish tomatoes had a greater carbon footprint than those imported from Spain, due to the energy required to operate greenhouses in their climate unless of course the low grade heat energy was obtained as a byproduct of another process such as electricity generation. Just talking about distance also ignores the fact that different modes of transport have radically different footprints, with air freight being considerably more carbon-intensive and inefficient than shipping. Depending on the country and the product in question, however, air freight may still be more ecofriendly than trying to grow something locally using energy-hungry methods. Perhaps we should just go without fruit and vegetables that are out of our growing season. Yes ! you’ve said it, just like the old days !

Wendell Berry, the American farmer, writer and thinker, famously said that “Eating is an agricultural act”. The quote now has a life of its own, but it is worth remembering that Berry used this quote in the context of “eat responsibly”. To do that, though, you have to understand how agriculture and the food we eat are connected, how they form part of an entire system.

Transporting food around the UK accounts for nearly 25 per cent of all the trips made by heavy goods vehicles, adding up to around 20 billion miles a year without even taking into account air and sea freight. Whilst only 1% of food is transported by air, it is responsible for around 11 per cent of the total carbon emissions from UK food transport. Worryingly, it is also the fastest-growing way of moving food around, according to latest figures from the Department for Environment, Food and Rural Affairs (DEFRA).

A simple idea: The idea behind the whole food miles thing is a very simple one – and the clue is, obviously, in the name; it is a way of expressing just how far the food we eat travels from the farm where it is first produced, before it ends up on our tables. In practice, however, it is not necessarily a straightforward thing to work out, since the journey from field to plate is not always a direct one. As a result, this distance may also include any number of other trips along the way, from farm to processor, from one processor to another, from processors to distribution centres, from there to the retailer and then finally to our homes. Worst of all, some of the journeys are very long indeed; in the fishing industry, for instance, there are tales of some of the fish and shellfish caught in Scotland travelling as far as China for
processing, before making its way back to European tables.

Just moving food up and down the country already represents huge distances travelled, but add all that is involved in bringing much of it into the UK by air, rail or ship in the first place, and it quickly becomes very clear that what we eat, consumes a lot of resources before ever we see it on our plate. Cut the food miles, source locally, cut the carbon dioxide– or so the thinking goes; but is it really that simple?

It is also important to think about the wider carbon costs involved in food production; locally produced food, it seems, may not automatically have the edge. A DEFRA study, for instance, concluded that it was less environmentally friendly to grow tomatoes in the UK than to import them from Spain, as in Sweden, because heating British greenhouses used more energy than the transport. There are other examples too, which show that when you factor in things such as energy usage, fertilisers, feed and pesticides, the embodied energy balance does not always favour local produce.

Based on the farm-gate value of unprocessed food in 2017, the UK supplied just under half (61%) of the food consumed in the country. The leading foreign suppliers of food consumed in the UK were countries from the EU (34%). Africa, Asia, North and South America each provided a 4% share of the food consumed in the UK. The three largest value imported commodity groups (at 2017 prices) were fruit and vegetables, meat and beverages.

Britain produces 80% of the cheese and beef consumed by the nation, but over half of our vegetables are imported.

  • Cheese: 80% UK and 20% EU.
  • Beef: 80% UK and 20% EU.
  • Tomatoes: 45% UK and 55% EU.
  • Broccoli: 45% UK and 55% EU.

How much food does the UK currently produce? The UK grows 61% of the food it eats, according to the National Farming Union (NFU),Tim Lang, Professor of Food Policy at City, University of London, and DEFRA’s Agriculture in the UK paper (July 2017).

Historically how much food has the UK produced? To find the highest historical rates for self-sufficiency in Britain, you need to go back to the 18th century with a much lower population. Historic modern-day lows include just before the First World War and before the Second World War, when we produced only around 33% of our food. The recent highest near self sufficiency was 82% in the early 1980s.

Fruit and vegetables The UK has a huge deficit in fruit and vegetable production. In 2015, imports of fruits to the UK were valued at £3.1 billion; imports of fresh vegetables (excluding potatoes) at £2.1 billion. UK exports of fruit and vegetables were valued at £199 million in 2015, less than 4% of the value of imports. The UK is self-sufficient in pre-packed potatoes but imports processed potatoes.

But what about waste food? In 2009, WRAP (Waste & Resources Action Programme) identified that UK households dispose of 8.3 million tonnes of food and drink waste every year, most of which could have been consumed without health risk. This avoidable food waste has a value of at least £12 billion. However, financial cost is not the only impact. By wasting food, we also waste the water and energy that was used to grow and process those foods, create greenhouse gas emissions, and have a range of other environmental impacts.

It is estimated that avoidable food waste is responsible for greenhouse gas emissions of 20 million tonnes CO2 equivalent per year, accounting for the whole life cycle. Avoidable food waste represents approximately 3% of the UKs domestic greenhouse gas emissions, with further emissions from overseas components of the supply chain. Two thirds of emissions associated with food waste occur in the UK, and these emissions are equivalent to those produced by over 7 million cars per year. The most significant contributors to avoidable carbon emissions are milk waste,
coffee waste and wheat products (bread, cake etc.). By reducing food waste, householders make a significant contribution to addressing current environmental concerns in the UK and abroad.

Sally Campbell,
Lamlash, Isle of Arran.