If you think you can make the planet better by clever shopping, think again. You might make it worse.You probably go shopping several times a month, providing yourself with lots of opportunities to express your opinions. If you are worried about the environment, you might buy organic food; if you want to help poor farmers, you can do your bit by buying Fairtrade products; or you can express a dislike of evil multinational companies and rampant globalization by buying only local produce. And the best bit is that shopping, unlike voting, is fun; so you can do good and enjoy yourself at the same time.Sadly, it’s not that easy. (41) . People who want to make the world a better place cannot do so by shifting their shopping habits: transforming the planet requires duller disciplines, like politics.Organic food, which is grown without man-made pesticides and fertilisers, is generally assumed to be more environmentally friendly than conventional intensive farming, which is heavily reliant on chemical inputs. But it all depends on what you mean by "environmentally friendly". Farming is inherently bad for the environment: since humans took it up around 11 000 years ago, the result has been deforestation on a massive scale.(42) . Organic methods, which rely on crop rotation, manure and compost in place of fertiliser, are far less intensive. So producing the world’s current agricultural output organically would require several times as much land as is currently cultivated. There wouldn’t be much room left for the rainforest.Fairtrade food is designed to raise poor farmers’ incomes. It is sold at a higher price than ordinary food, with a subsidy passed back to the farmer. But prices of agricultural commodities are low because of overproduction, (43) .Surely the case for local food, produced as close as possible to the consumer in order to minimise "food miles" and, by extension, carbon emissions, is clear Surprisingly, it is not. A study of Britain’s food system found that nearly half of food-vehicle miles (i. e. , miles travelled by vehicles carrying food) were driven by cars going to and from the shops. Most people live closer to a supermarket than a farmer’s market, so more local food could mean more food-vehicle miles. Moving food around in big, carefully packed lorries, as supermarkets do, may in fact be the most efficient way to transport the stuffWhat’s more, once the energy used in production as well as transport is taken into account, local food may turn out to be even less green. (44) . And the local-food movement’s aims, of course, contradict those of the Fairtrade movement, by discouraging rich-country consumers from buying poor-country produce. But since the local-food movement looks suspiciously like old-fashioned protectionism masquerading as concern for the environment, helping poor countries is presumably not the point.(45) . The problems lie in the means, not the ends. The best thing about the spread of the ethical-food movement is that it offers grounds for hope. It sends a signal that there is an enormous appetite for change and widespread frustration that governments are not doing enough to preserve the environment, reform world trade or encourage development. 41（）

A. The aims of much of the ethical-food movement--to protect the environment, to encourage development and to redress the distortions in global trade--are admirable.
By maintaining the price, the Fairtrade system encourages farmers to produce more of these commodities rather than diversifying into other crops and so depresses prices--thus achieving, for most farmers, exactly the opposite of what the initiative is intended to do.
C. Proper free trade would be by far the best way to help,poor farmers. Taxing carbon would price the cost of emissions into the price of goods, and retailers would then have an incentive to source locally if it saved energy.
D. There are good reasons to doubt the claims made about three of the most popular varieties of "ethical" food: organic food, Fairtrade food and local food.
E. But following the "green revolution" of the 1960s greater use of chemical fertiliser has tripled grain yields with very little increase in the area of land under cultivation.
F. And since only a small fraction of the mark-up on Fairtrade foods actually goes to the farmer--most goes to the retailer-the system gives rich consumers an inflated impression of their largesse and makes alleviating poverty seem too easy.
G. Producing lamb in New Zealand and shipping it to Britain uses less energy than producing British lamb, because fanning in New Zealand is less energy-intensive.