杏吧原创

Meat is bad: bad for you, bad for the environment. At least, that鈥檚 the usual argument. Each year, the doors to the UN climate negotiations, which kick off again in Durban, South Africa, on 28 November, are assailed by demonstrators brandishing pro-vegetarian placards. The fact is that livestock farming accounts for a whopping 15 per cent of all greenhouse gas emissions. We can鈥檛 all go veggie, so just how much meat is it OK for an eco-citizen to eat?

It鈥檚 not just the demonstrators who are concerned about food鈥檚 impact on the climate. This week, a major report concludes that food production is too close to the limits of a 鈥渟afe operating space鈥� defined by how much we need, how much we can produce, and its impact on the climate.

Meat is a major contributor to that: , and the problem is getting worse. As people get richer, the demand for protein gets stronger, says Molly Jahn, a former undersecretary at the US Department of Agriculture, and one of the authors of Achieving Food Security in the Face of Climate Change, commissioned by the (CGIAR).

It鈥檚 unrealistic to expect everyone to give up meat entirely, and many of the world鈥檚 poor need to increase their meat consumption to overcome malnutrition and food insecurity.

The solution is to eat less meat rather than no meat.

In 2007, of the Australian National University in Canberra estimated that the average person consumed 100 grams of meat a day, or about one burger (a quarter-pounder is 113聽g). The rich eat 10 times more than the poor 鈥� in other words, some people get 10 burgers a day while others get none.

Butler showed that if every person in the world ate 50聽g of red meat and 40聽g of white meat per day by 2050, greenhouse gas emissions from meat production would stabilise at 2005 levels 鈥� a target cited in national plans for agricultural emissions. That鈥檚 about one burger and one small chicken breast per person every two days (The Lancet, DOI: 10.1016/S0140- 6736(07)61256-2).

Butler鈥檚 2007 figures didn鈥檛 take into account the fact that we throw out a lot of the animal mass produced because we consider it inedible. Western countries are the biggest offenders: while many cultures are not fazed by a meal of brains or testicles, Butler estimates that Americans and Australians throw out up to half the cow mass they produce.

At New 杏吧原创鈥榮 request, he updated his calculations. He estimates that globally we discard between 5聽and 10聽per cent of the animal. This means we can only allow ourselves 80 to 85聽g of red and white meat, or one burger and one chicken fillet every three days.

That鈥檚 an upper limit. Emissions may need to be cut further.

Our allowance would drop further if more people were as wasteful as the Americans and Australians. And, according to CGIAR, in addition to the waste between the abattoir and the plate, one-third of all produced food is spoiled because of poor refrigeration, pests and bulk packaging that encourages consumers to buy more than they can eat. All of which eat into our meat allowance.