For decades, environmental arguments against eating meat have been largely the preserve of vegetarian websites and magazines. Just two years ago it seemed inconceivable that significant numbers of western Europeans would be ready to down their steak knives and graze on vegetation for the sake of the planet. The rapidity with which this situation has changed is astonishing.

The breakthrough came in 2006 when the UN Food and Agriculture Organisation (FAO) published a study, Livestock's Long Shadow, showing that the livestock industry is responsible for a staggering 18% of all anthropogenic greenhouse gas emissions. This is only the beginning of the story. In 2008, Brazil announced that in the 12 months to July it had lost 12,000 sq km (3m acres) of the Amazon rainforest, mainly to cattle ranchers and soy producers supplying European markets with animal feed. There is water scarcity in large parts of the world, yet livestock-rearing can use up to 200 times more water a kilogram (2.2lbs) of meat produced than is used in growing wheat. Given the volatile global food prices, it seems foolhardy to divert 1.2bn tonnes of fodder - including cereals - to fuel global meat consumption, which has increased by more than two and half times since 1970