The Guardian, By George Monbiot, December 25
The figures were so astounding that I refused to believe them. I found them buried in a footnote, and assumed at first that they must have been a misprint. So I checked the source, wrote to the person who first published them, and followed the citations. To my amazement, they appear to stand up.
A kilogramme of beef protein reared on a British hill farm can generate the equivalent of 643kg of carbon dioxide. A kilogramme of lamb protein produced in the same place can generate 749kg. One kilo of protein from either source, in other words, causes more greenhouse gas emissions than a passenger flying from London to New York.
This is the worst case, and the figure comes from a farm whose soils have a high carbon content. But the numbers uncovered by a wider study are hardly reassuring: you could exchange your flight to New York for an average of 3kg of lamb protein from hill farms in England and Wales. You’d have to eat 300kg of soy protein to create the same impact.
As the world’s people adopt the western diet, a paper in the Climatic Change journal estimates, the methane and nitrous oxide produced by farming could rise to the equivalent of 13bn tonnes of carbon dioxide a year by 2070. This is more than all human activities combined can safely produce without exceeding 2C of global warming. Climate breakdown looks inevitable – unless we all change our diets.