UNITED KINGDOM, June 26, 2014 (New Scientist): As much as a quarter of our greenhouse gas emissions come from food production. But it's not clear how much would really be saved if people swapped their beef steaks for tofu burgers. On some estimates, going vegetarian could cut out 25 per cent of your diet-related emissions. But it all depends on what you eat instead of the meat. With some substitutions, emissions could even rise.
So Peter Scarborough and his colleagues at the University of Oxford took data on the real diets of more than 50,000 people in the UK, and calculated their diet-related carbon footprints. "This is the first paper to confirm and quantify the difference," says Scarborough.
They found that the benefits could be huge. If those eating more than 100 grams of meat a day went vegan, their food-related carbon footprint would shrink by 60 per cent, saving the equivalent of 1.5 tonnes of carbon dioxide a year. Perhaps more realistically, if someone eating more than 100 grams of meat a day simply cut down to less than 50 grams a day, their food-related emissions would fall by a third. That would save almost a tonne of CO2 each year, about as much as an economy return flight between London and New York.
"This research presents a strong case for the greenhouse gas benefits of a low-meat diet," says Christopher Jones of the University of California, Berkeley. In 2011, Jones compared all the ways US households can cut their emissions. Although food was not the biggest source of emissions, it was where people could make the biggest and most cost-effective savings, by wasting less food and eating less meat. Jones calculated that saving each tonne of CO2 emissions would also save the household $600 to $700 (Environmental Science & Technology, DOI: 10.1021/es102221h).