Warning: your festive meal could be more damaging than a long-haul flight
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.
A paper published a few days ago suggests that switching from meat to green vegetables would be environmentally damaging. Per calorie, growing lettuces produces more greenhouse gases than rearing pork. But all this establishes is that lettuces are low in calories. You would need to eat 15kg of lettuce in order to meet your daily energy requirement, which might be reasonable if you were a 200kg rabbit. As another study remarks, “20 servings of vegetables have less greenhouse gas emissions than one serving of beef”.
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.All sorts of questions jump out here:
- How much lettuce would an ordinary size rabbit eat per day?
- Does a human need more or less lettuce than a rabbit, proportionate to its size?
- In the final paragraph, how much meat is he assuming will be eaten per person per year on average? Is that reasonable?
How much does an adult human weigh in kg? I genuinely don't know.
1kg is about 2.2 pounds. 1 stone is 14 pounds, so 1 stone is just over 6kg. A 12 stone adult would therefore weigh over 12 x 6kg = 72kg. The rabbit can weigh nearly three times that, so it needs less food.
13 billion tonnes is 13 000 billion kg. Dividing by 650kg (using the figures from the first paragraph) you get 20 billion kg of meat protein. There are about 7 billion people on the planet, so that is about 3kg per person per year.
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