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the largest source of carbon dioxide emissions in the farm sector, but these emissions are not included in the government’s figures for agricultural emissions. Sheep and cows emit methane as a result of the digestive process, resulting in high levels of emissions from livestock and dairy farming.

      Meat farming is responsible for two thirds of the nitrous oxide and more than a third of the methane associated with human activity. One study found that every 1 kg of beef produced results in emissions of more than 36 kg of carbon dioxide equivalent: two-thirds of the energy used goes to produce and transport cattle feed. Producing food for livestock and clearing land for grazing is having a huge impact on valuable forests. Greenhouse gas emissions from livestock have been put at around 18 per cent of the global total. And demand for meat is rising, especially in the developing world: meat production is predicted to double between 2000 and 2050.

      the UK’s carbon footprint

      Despite the government’s recognition that climate change is a greater threat than terrorism, UK emission levels have continued to rise over the past decade.

      Some parts of the economy have started to reduce their carbon footprint, but emissions from transport and electricity generation are rising – the latter the result of the recent switch back to coal in power stations.

      The government’s draft Climate Change Bill set a target of cutting carbon dioxide emissions by 60 per cent by 2050. But science suggests that this will not be enough. ‘It is clear to us that climate science suggests that this figure may not be adequate to prevent global temperatures rising above dangerous levels,’ said a House of Commons Joint Committee on the Draft Climate Change Bill in August 2007.

      The crucial factor is not the target at some distant point in the future, but how much carbon dioxide is building up in the atmosphere. Making cuts sooner rather than later will result in less carbon in total. If the UK is committed to keeping global temperatures within 2°C it may need to look at cuts of 90 per cent by 2050.

      eating our way to climate change

      The contribution of food to global warming doesn’t stop at the farm gate. More than 30 per cent of greenhouse gas emissions in Europe are estimated to come from the food and drink sector. In the UK the food chain contributes more than one in every five tonnes of greenhouse gas emissions.

      Much of the food on our supermarket shelves has travelled the world, some of it ‘air-freighted for freshness’, some by ship – and almost all of it by road. A piece of beef can travel 12,000 miles just to reach the UK shops. Ninety per cent of the fruit we eat and 40 per cent of our veg are imported into the UK. Air freight has the highest emissions of carbon dioxide per tonne of food – and is being used more and more.

      Even food from the UK tends to be well-travelled. The average potato’s journey starts at the farm, goes by lorry to a factory or warehouse for packaging and is then taken by lorry to a centralised warehouse before distribution to the stores. One in four heavy goods lorries on UK roads are transporting food, clocking up 5.5 million food miles in 2004. That’s the equivalent of one potato travelling 220 times around the Earth. But on average, lorries are only just over half full. More efficient distribution could greatly reduce the impact of food miles.

      Focusing only on food miles ignores the fact that producing and processing food accounts for around 14 per cent of energy consumption by UK businesses; and food, drink and tobacco manufacturers consume more energy than is used in iron and steel production. Keeping food cool contributes to the emissions total: fresh food, especially meat, is stored and transported in refrigerated containers that produce greenhouse gases.

      Globally, food production contributes around 30 per cent of total greenhouse gas emissions, half of which come from methane. And to think that on average we throw away around a third of the food we buy – where, left to rot in a landfill, it generates yet more methane.

      the footprint of a packet of crisps

      To discover the carbon footprint of a standard packet of Walkers Cheese & Onion Crisps, the Carbon Trust plotted out the key stages of Walkers’ supply chain, from sowing the potato and sunflower seeds (for the oil) through to getting the crisps on the shelves and disposing of the packet. By looking at the energy consumption of each stage, and converting this into emissions, it worked out the total carbon footprint. Result: a packet of Walkers Cheese and Onion Crisps has a footprint of 75 g.

      business as usual?

      Do nothing to cut carbon dioxide emissions and the amount in the atmosphere will just build up. Climate modellers describe this scenario as ‘business as usual’. It assumes that emissions continue to rise at current rates – assuming continuing growth in the economy, and the on-going use of fossil fuels. If this were to happen, carbon dioxide emissions from fossil fuel would more than double by 2050 globally. Yet if we reduce the amount of energy we use, or start to switch to non-fossil fuel energy, we will slow down the rate of growth in emissions. It may sound obvious but the faster we make changes, the quicker carbon dioxide levels will stabilise.

      ‘The investments made in the next 10-20 years could lock in very high emissions for the next half-century, or present an opportunity to move the world onto a more sustainable path.’ Stern Review

      how can the cuts be achieved?

      There are many ways to curb greenhouse gas emissions. But the biggest savings will come from two simple strategies: using less energy and using cleaner fuels. We look at these more closely in the next two chapters.

       chapter 4

       saving energy

      Saving energy is a great way to shrink our carbon footprint. In fact it’s the first thing we should do. Why spend on power that we don’t really need?

      save it

      If we’re to play our part in reducing the dangers of climate change, we need to make serious cuts in our energy use. But how can these cuts best be made? In Chapter 7 you’ll find out what you can do as an individual, but here we look at the first big steps we can take as a society to save energy.

      where the savings will come from

      Imagine living in a home that was so well designed and insulated that it almost heated itself. Or living in a city where clean, fast public trains and buses turned up on time and took you where you needed to go. Where traffic jams, road rage and pollution were a thing of the past.

      Making our energy work harder doesn’t mean going back to the Dark Ages – or even to the winter of 1974 when a three-day working week, electricity rationing and power cuts got the country through an energy shortage. Although we use more energy now than we did in the 1970s, we can save more as well. In fact the UK could cut its energy use by nearly a third just by eliminating waste.

      In 2007 the government outlined energy-saving measures that would reduce carbon emissions by 6 per cent by 2020, saying that two-thirds of those savings would be from households, a quarter from business and 10 per cent from the public sector. Critics said even more could be done.

      reasons to use energy efficiently

      Fewer carbon emissions = cleaner air Fewer carbon emissions = better for the climate Do more with less = save money, reduce waste

      how can these cuts best be made

      The

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