Food
At the bottom of this page, we provide the chapter summary for this portion of 'How to Live a Low-Carbon Life'. This provides some of the main conclusions from the material covered in the main text. In the rest of this page, we comment on new products, research findings and offer feedback from customers. If it's only greenhouse gas emissions you are worried about, then it may be better to drive than to walk. First, please, a word of excuse. I don’t intend this piece as a recommendation to use your car. I want to make the case – explained in much more detail in 'How to Live a Low-carbon Life' – that modern food production is an important but under-recognised source of climate changing gases. Recent research, summarised in the New Scientist magazine of 18th July 2007, suggests that modern methods of intensive beef production generate large amounts of greenhouse gases. This is, of course, not a new hypothesis: we have gradually become aware of the huge amounts of grain needed to feed our animals, and of the troublesome amounts of energy needed to produce the fertiliser needed to get our cereals to grow. The scientist David Pimentel has suggested that it takes seven times as much grain to feed all meat animals in the US as it does to feed the human population. The new research, carried out in Japan but surely representative of the impact of modern farming methods in the rest of the industrial world, suggests that one kilogramme of meat creates the equivalent of over 36kg of global warming gases. This number immediately strikes one as large. The average person in the UK eats about 12 kilogrammes of beef a year. So eating a typical amount of beef generates 0.4 tonnes of emissions. After including the impact of international aviation, each UK citizen is responsible for about 12 tonnes of emissions from all sources, including industry. A simple sum shows that beef, a relatively small part of many people's diet, accounts for between 3 and 4% of one's carbon footprint. This is bad enough. But let's look at it another way which perhaps makes our concerns with food production even clearer. A simple calculation shows that industrial food production is more destructive of the global atmosphere than driving a car. In particular, if one walks to the shops, and eats something after the walk to put back the calories lost in the exercise, then it would generally be better to drive instead of walk. The greenhouse gas content of the top-up food might be greater than the emissions from the car. Here's an example. Walking three miles uses about 180 calories. Replacing, assuming you don’t want to lose weight, would mean eating about 100 grammes of beef. Of course, it depends on the cut of meat, and how much fat it contains, but this figure is reasonably typical of beef in British shops. The scientists in Japan give a figure of 36 kg of emissions for a kilo of meat, so a portion of 100 grammes equates to about 3.6kg. This is the first part of the calculation – it shows that one 3 mile walk generates 3.6kg of emissions if one replaces the energy lost with beef. What if one drove the 3 miles instead, and so didn’t need the extra food? The average UK car emits about 290 grammes (0.29kg) of CO2 for every mile travelled. A 3 mile trip therefore generates 0.87 kg of emissions. This is about a quarter of the equivalent emissions from walking. And if there are two of you, and you share the car, then walking would be eight times as bad for the climate. The troubling fact is that taking a lot of exercise and then eating a bit more food is not good for the global atmosphere. Eating less and driving to save energy would be better. I can't deny that this is a troubling conclusion. When I make similar arguments in public talks, I usually get an angry interruption. Why am I recommending driving, I get asked. The honest answer is – I'm not, I'm simply pointing out that modern agriculture is extraordinarily energy intensive. And it is not just energy. Cows belch gallons of methane every day and methane is a fiercer global warming gas than CO2. Manure and fertiliser also give off smaller quantities of nitrous oxide, which has over 300 times the impact of CO2. Intuitively we recognise that major industries such as aluminium smelting generate climate changing emissions. We need also to become accustomed to the idea that our food production systems, particularly those involving ruminant animals and their methane burps, are equally damaging. As the man from Ryanair says, cows generate more emissions than aircraft. Unfortunately, we have to agree with him. And it wouldn’t do any harm also to acknowledge that transport is getting slightly more energy efficient by the year bur as far we can tell this isn’t the case with the food supply chain. July 19th 2007 Bread - more energy used in a breadmaker or in a commercial bakery? Commercial bakeries ought to be more efficient. The ten thousand loaves in a huge oven should be sharing the heat. In response to a question from a web site visitor, I tried to find out whether breadmakers use more energy than a bakery. As usual, the answer is complicated. The best data I could find was a highly efficient bakery would take about 0.4kwh to make a loaf. These bakeries tend to be largest. Smaller bakeries might use double this amount. ( http://www.industry.gov.au/assets/documents/itrinternet/breadsummaryreport20040206153410.pdf) How does this compare to a domestic breadmaker? I'm afraid I found it extremely difficult to get measurements. The figures I eventually located were all informal, and usually personal measurements from people doing the calculation at home. But they did all concentrate around 1/3 of a kwh, or less than even the best bakeries. (In using the word 'best' I am, of course, referring to the energy efficiency of the process, not the quality of the product!). So we can be reasonably confident that a breadmaker uses less energy than a bakery though I had to assume that the loaves made in breadmaker were the same weight as a shop-bought version. Unfortunately, this doesn't mean it is less carbon intensive. A bakery will largely use gas, while your breadmaker uses electricity. In most countries of the world, electricity is at least twice as carbon intensive as gas. So the bread made at home is competitive in greenhouse gas terms with small bakeries, but not big. Simply put, it is unambiguously better to make bread than buy it from an instore bakery but it is less clear that a large industrial bakery isn't better. This isn't the whole truth. Shop bought bread needs shipping to the store from the bakery, and is usually packaged in plastic. But these factors are probably not overwhelmingly important in carbon terms. And another thing...... bread is usually made overnight at home. This is when energy is least carbon intensive, at least in the UK. At four in the morning almost half our energy is coming from nuclear plants. So if we really delved into this issue, we'd probably find that breadmakers actually score well. More important, perhaps, is that home baked bread is made on demand. You bake it when you want it. I suspect that less is wasted. And it tastes better than all but the best shop bread, contains less salt and sugar, has no preservatives and can be supplmented with good nutritious ingredients like flax seeds and walnuts. It's no contest. Marks & Spencer's 'Plan A' Please click on the PDF at the top of this page to read analysis of the practicality of M&S's zero emissions plans. (January 20th 2007) Organic box schemes and their impact on carbon emissions Riverford is one of the largest operators of organic box schemes in the UK. Its weekly newsletter (15th January 2007) gives some details of the results of a project to assess its own carbon footprint. Perhaps this work was partly prompted by a concern that schemes such as Riverford's, which ship food from Devon to most of southern UK and which use substantial volumes of imported food in winter, were little better than air-freighted supermarket food. The results are encouraging. Riverford estimates that each box typically generates about 1.8kg of carbon dioxide. (The newsletter actually says 'carbon', but I have checked and Riverford meant CO2). Since just one kilo of airfreighted food from the US probably emboides several times this volume of CO2 without considering the carbon costs of retailing or shopppers' travel, this is a good result. Riverford suggests that one of its boxes represents just 0.25% of the typical UK resident's carbon dioxide emissions. We shouldn't be too complacent: this means one box a week produces more CO2 than the typical person in th poorest countries generates from all his or her activities. Chapter Summary The food industry, one of the most carbon-intensive in the world, is by far the largest indirect contributor to UK emissions. The figures in this chapter suggest that producing and distributing food creates over five times the volume of the most energy-intensive manufacturing industry: iron and steel.213 This isn’t just about the carbon costs of transporting foodstuffs. The issue of ‘food miles’ is now becoming well understood; but it is only a small portion of the problem. The whole chain of supply is a huge user of fossil fuel from fertilizer on the fields to customers’ cars going to supermarkets. This chapter suggests that the food industry adds over 2 tonnes of greenhouse gases to the individual’s total emissions every year, or about one sixth of the total. This figure may actually be too low, since it excludes the carbon dioxide and methane emitted by the soil in intensive agricultural systems. This is still higher than some estimates: a recent UK government study put the total at 8 per cent of the UK’s energy needs, but omitted consideration of fertilizer production, packaging costs and methane from cows, though it does include the costs of running supermarkets.214 The energy used to provide the food on our tables is about nine times greater than the calorific value of the food itself. Changing food purchase habits can dramatically alter the climate change impact of our lifestyle. In its implications, it is comparable to the decision to abandon air travel. The three most important rules are these: buy organic where possible, local when available, and keep away from processed and packaged food.
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