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Food has always been at the top of the sustainable development agenda focusing on prominent issues such as food security, land rights, soil degradation and trading relationships. Now there is a growing recognition that how we grow, distribute, store, sell and consume food also makes a significant contribution to one of the greatest sustainability threats of all – climate changing greenhouse gas emissions.
Globally, the main greenhouse gas (GHG), carbon dioxide, accounts for about 72 per cent of all GHG emissions. However there are other GHGs, and these are particularly associated with the food chain. Methane, much of which comes from grazing livestock, contributes 20 per cent while arable soils and livestock wastes contributes to the amount of nitrous oxide which, in turn, adds another seven per cent to the total global warming effect.
How food contributes to greenhouse gas emissions
Most research on food and its greenhouse gas impacts so far has been undertaken by developed countries, such as Sweden, the UK and the Netherlands. These country specific studies put the food chain’s contribution to national emissions at about 20 per cent. However a major EU wide study puts the contribution higher still at 31 per cent of all EU GHG emissions (see Environmental impact of products (EIPRO): Analysis of the life cycle environmental impacts related to the total final consumption of the EU25, European Commission Technical Report EUR 22284 EN, May 2006).
Transport or agriculture as main source of food GHG emissions?
Most of the attention on food and its GHG contribution has, until now, centred on the ‘food miles’ issue, ie the environmental impacts of long distance transport arising from increasingly globalised food sourcing and distribution patterns. However, life cycle based studies that look at the food system as a whole increasingly show that transport is only part of the picture. An understanding of food’s GHG contribution requires us to consider emissions at all stages in the food chain including agricultural production, manufacturing, refrigeration, transport, packaging, retail, home storage, cooking and waste disposal. A change in practice at one point in the food chain can positively or negatively affect emissions at another stage. The Figure gives an estimated breakdown for the UK.
Source: Overall food consumption related greenhouse gases, Food Climate Research Network.
Agriculture accounts for almost half of food-related greenhouse gas emissions, or between 10 and 15 per cent of total national contributions to greenhouse gas emissions. It is agricultural production, rather than food transport, that poses the major challenge.The latest report by the Intergovernmental Panel on Climate Change (IPCC AR4, Working Group III) estimates agriculture to contribute to 10-12 per cent of anthropogenically generated greenhouse gases. Grazing livestock (cattle, sheep and goats), together with rice cultivation, are responsible for major fluxes of methane, while both arable soils and livestock wastes are potent sources of nitrous oxide.While the agricultural stage of food production represents the main cause for concern, the importance of other supply chain stages may be greater for some particular foods. Potatoes, chickpeas and tea leaves, for example, are less greenhouse gas intensive to grow they are to cook. Think of cooking a baked potato in an oven, boiling chickpeas for an hour till soft, or switching the kettle on for tea. For frozen vegetables, the refrigeration stage will dominate as an ‘emission hotspot.’ And for the very small proportion of foods that are transported by air, the emissions generated during this stage will dominate by a very long way.
Taking a product focused approach
Given these variations, a product focused approach may be more appropriate.
Fruit and vegetables
UK calculations suggest that fruit and vegetable consumption, both indigenous and imported, accounts for around 2.5 per cent of all UK GHG emissions once the growing, refrigeration and transport activities are taken into account. Trends also suggest that in the UK, as elsewhere in the developed world, our preference for the more emission-intensive types of produce is growing. These include fruits and vegetables that, because of their short shelf life, are air freighted, or those that are cultivated beyond their natural growing season in energy intensive heated glasshouses. We are also increasing our consumption of inherently fragile and spoilable produce, such as berry fruits and salads. These require rapid and energy intensive modes of transport, packaging to prevent spoilage, and are prone to damage with high wastage rates.
Meat and dairy
Meat and dairy products are the foods that are by far the most GHG intensive, accounting for around eight per cent of the UK’s GHG emissions, or nearly 50 per cent of total food related impacts (Meat and dairy production & consumption: Exploring the livestock sector’s contribution to the UK’s greenhouse gas emissions and assessing what a less GHG intensive system of production and consumption might look like, Food Climate Research Network, November 2007).In addition, a major report by the Food and Agriculture Organisation states that globally, livestock account for 18 per cent of world GHG emissions, a figure that includes livestock-induced deforestation and associated emissions (this explains the disparity with the IPCC figure highlighted earlier). What is more, global consumption of these foods is set to grow, particularly in the developing world where it is predicted to double by 2030. This in turn will mean increases in emissions.
Past and projected trends in milk and meat consumption
Source: Livestock’s Long Shadow – Environmental Issues and Options, FAO, December 2006
Taking a staged approach
How significant a contribution do particular technologies associated with the food chain such as transport and refrigeration make to food emissions?
Nearer/farer?
Popular opinion believes that reducing ‘food miles’ will lead to reductions in food related greenhouse gas emissions. However, nearer may not always be better. In the UK, for example, growing British tomatoes in heated greenhouses in winter will generate more emissions than importing them from Spain where growers benefit from ‘free’ sunlight. This said, food transport emissions worldwide are growing and new infrastructure developments, such as roads, ports and airports, will not only generate emissions in the construction but will also make further globalisation increasingly cost effective and inevitable. As such there are likely to be future, second order impacts associated with transport.The use of air freight for all commodities is growing, and the flying of food is growing fastest of all. This in turn reflects our desire for highly perishable goods, particularly fresh fruit and vegetables. According to one study, during the UK growing season, imported Kenyan green beans imported are 20-26 times more GHG intensive than their UK seasonal counterparts. The issue is more complex than simply greenhouse gas quantification. Almost all the top 20 air freight importers into the UK (by volume) are from developing countries. Around 1-1.5 million people depend directly or indirectly on export horticulture in sub-Saharan Africa for example. Banning air freighted imports in the name of emissions reduction might have damaging consequences of these people since the highly perishable goods they produce cannot (yet) be transported by other means. This said, sea freight technology is now moving on and it may be that in coming years, with suitable investment and support, shipping can substitute for air.
Refrigeration and wastage
For some foods, refrigeration represents the major, an ‘emission hotspot.’ Its use has both beneficial and negative consequences for emissions. In the developed world refrigeration is used at almost every stage in the supply chain and plays a vital role in reducing waste. This is up to the point where people bring food home; after that, cultural attitudes, cheap food and somewhat blasé attitudes to food wastage mean up to a third of household food, most of it edible, is thrown away. This is a major concern since wasted food represents a waste of all the embedded GHG emissions associated with growing, distributing and selling that food. Where it can prevent food waste, refrigeration helps avoid the emission of greenhouse gases.In the developing world, post harvest losses are greater because there is less access to refrigeration and clearly more and better refrigeration could help reduce spoilage. But refrigeration comes with its own greenhouse gas burdens because of the refrigerant gases used which have a high global warming potential and, more significantly, due to the energy they require. In the UK refrigeration is estimated to account for 2.4 – 3.5 per cent of total greenhouse gas emissions. Some refrigeration use is unavoidable and desirable. However its ready availability means that a ‘refrigeration dependence’ culture has developed. The types of foods we consume are now predicated on refrigeration’s existence. A warming global climate might also increase our reliance on, and need for, refrigeration particularly if we are not prepared to accept changes to the sorts of foods we consume.
Climate change impacts on food supply
The food system has an impact on climate change but the reverse is also true. A warming climate is likely to present major challenges to current systems of agricultural production and food provisioning. Poorer parts of the world that tend to be in the lower latitudes are likely to experience the worst effects of climate change, including drought or flooding, or both. Richer countries in Northern Europe and North America may find that initially warmer temperatures and longer growing seasons actually favour agricultural production, but by 2050 the negative impacts of high temperatures and water shortages will start to hit. Climate change could also trigger changing patterns of crop and livestock disease while extreme weather events could disrupt transport systems and stationary infrastructure.
Reducing food related greenhouse gas emissions
What can be done to reduce food related greenhouse gas emissions? How far will technology solve our problems? A great deal, technologically speaking, can in fact be done. For agriculture, examples include breeding crops to take up nutrients more effectively (meaning less nitrogen staying in the soil and turning into nitrous oxide). There is also massive scope for improving manufacturing and refrigeration efficiency through better equipment design and maintenance. Alternative and renewable fuel sources, such as biogas, and emerging technologies, such as trigeneration (combined heat, power and coolness), can also reduce the carbon intensity of processes and reduce emissions. Some manufacturers have started to use these technologies with demonstrable success.
Developing more efficient transport systems and shifting goods, where possible, to cleaner modes such as shipping and rail will also help. In the home, more efficient refrigerators, cookers and boilers are entering the market and will make a difference.
It is not clear, however, whether these improvements will get us to the 80 per cent reduction in greenhouse gas emissions that we need to achieve by 2050 if we are to keep below a 2˚C rise in temperatures, above which ‘dangerous climate change’ becomes a distinct possibility. We may also need to address what and how we consume, shifting our habits in less greenhouse gas intensive directions. This will mean reducing substantially, in the developed world, or curtailing growth in, for the developing world, our consumption of meat and dairy products. It may also involve rethinking our growing reliance on refrigerated or highly processed foods and consuming more seasonal, robust produce; produce that does not need delicate handling or storage or rapid transport modes. Importantly, it will mean wasting less food so that less needs to be produced in the first place.
All this very clearly goes against current and emerging patterns of consumption. In the developed world, our food system is predicated on the availability of cheap food, and particularly cheap meat and dairy products, provided by a sophisticated and economically efficient manufacturing and retail infrastructure. The signs are that the rapidly growing middle classes in the developing world aspire to similar lifestyles and a food industry is rapidly developing to cater to such aspirations. At present, there are few indications that policy makers anywhere in the world are willing to tackle excessive consumption although some are at least starting to talk cautiously about the issue. The danger is that if we do not take steps now to address what and how much we consume, a changing climate may force altered patterns of consumption on us. And if this arises, the fear is that those who have very little already will, as ever, stand to lose the most.
