"how to live a low-carbon life", aka - those damaging methane burps

food

recent research, summarized in the new scientist magazine of 18th july 2007, suggests that modern methods of intensive beef production generate large amounts of greenhouse gases. this is, of course, not a new hypothesis: we have gradually become aware of the huge amounts of grain needed to feed our animals, and of the troublesome amounts of energy needed to produce the fertilizer needed to get our cereals to grow. the scientist david pimentel has suggested that it takes seven times as much grain to feed all meat animals in the US as it does to feed the human population.
the new research, carried out in japan but surely representative of the impact of modern farming methods in the rest of the industrial world, suggests that one kilogram of meat creates the equivalent of over 36kg of global warming gases. this number immediately strikes one as large. the average person in the US eats about 12 kilogram of beef a year. so eating a typical amount of beef generates 0.4 tons of emissions. after including the impact of international aviation, each US citizen is responsible for about 12 tons of emissions from all sources, including industry.
a simple sum shows that beef, a relatively small part of many people's diet, accounts for between 3 and 4% of one's carbon footprint. this is bad enough. but let's look at it another way which perhaps makes our concerns with food production even clearer. a simple calculation shows that industrial food production is more destructive of the global atmosphere than driving a car.

here's an example. walking three miles uses about 180 calories. replacing, assuming you don’t want to lose weight, would mean eating about 100 grams of beef. of course, it depends on the cut of meat, and how much fat it contains, but this figure is reasonably typical of beef in US shops. the scientists in japan give a figure of 36 kg of emissions for a kilo of meat, so a portion of 100 grams equates to about 3.6kg. this is the first part of the calculation – it shows that one 3 mile walk generates 3.6kg of emissions if one replaces the energy lost with beef.
what if one drove the 3 miles instead, and so didn't need the extra food? the average US car emits about 290 grams (0.29kg) of CO2 for every mile traveled. a 3 mile trip therefore generates 0.87 kg of emissions. this is about a quarter of the equivalent emissions from walking. and if there are two of you, and you share the car, then walking would be eight times as bad for the climate, if both are replacing the energy lost with beef. the troubling fact is that taking a lot of exercise and then eating a bit more food is not good for the global atmosphere. eating less and driving to save energy would be better. i can't deny that this is a troubling conclusion.

why am i recommending driving? the honest answer is – i'm not, i'm simply pointing out that modern agriculture is extraordinarily energy intensive. and it is not just energy. cows belch gallons of methane every day and methane is a fiercer global warming gas than CO2. manure and fertilizer also give off smaller quantities of nitrous oxide, which has over 300 times the impact of CO2. intuitively we recognize that major industries such as aluminium smelting generate climate changing emissions.
we need also to become accustomed to the idea that our food production systems, particularly those involving ruminant animals and their methane burps, are equally damaging. as the man from delta air says, cows generate more emissions than aircraft. unfortunately, we have to agree with him. and it wouldn’t do any harm also to acknowledge that transport is getting slightly more energy efficient by the year but as far we can tell this isn’t the case with the food supply chain.