Globe and Mail writer, Neil Reynolds, wrote an excellent column yesterday, linking meat to global warming and other environmental problems.

Here are some highlights:

“Livestock emit more greenhouse gases into the atmosphere than all of the cars, freight trucks, railways, airplanes and container ships in the entire world.”

“Together, livestock animals account for 20 per cent of terrestrial animal biomass – in other words, of all living land creatures, humans included. ...livestock biomass increased from 428 million tonnes in 1960 to 700 million tonnes in 2000.”

“Feed crops take 30 per cent of the world's arable land. Livestock command 70 per cent of the planet's agricultural land and 30 per cent of its entire land surface.”

“These animals emit 9 per cent of human-induced carbon dioxide, 37 per cent of human-induced methane, 64 per cent of human-induced nitrous oxide and 65 per cent of human-induced ammonia. ...ammonia is a well-known cause of acid rain.”

“Canadians and Americans consume almost 100 kilograms of meat, per capita, per year (which requires the killing of 10 billion animals).”

“Greenhouse gas emissions from beef, pork and chicken are every bit as human in origin as the emissions from cars and trucks – and every bit as serious.”

Two interesting arguments were raised by commenters:

1. The source of CO2 that cows emit is from food, which is renewable and is taken out of the atmosphere when crops are grown.

Jan Steinman responded: "That would be great were it true. But the so-called "green revolution" of mechanized, industrialized agriculture is entirely based on fossil fuel products. Ten calories of petroleum go into each calorie of food produced. So the CO2 emitted by today's domesticated ruminants largely comes from underground, not from current uptake of CO2 by plant material, as was true of wild animals in the past.

... Fertilizer comes from natural gas. Pesticides come from petroleum, as does fuel for tractors and irrigation pumps. And don't forget that most irrigation is from "fossil water" that is in decline in many large aquifers."

2. How are domesticated farm animals contributing any more greenhouse gasses than the millions of wild grass-chewers (caribou/bison/etc) who were here before?

Domesticated grazing animals are far denser in population than the wild animals that they displaced. Wild grasslands supported a diverse range of species and were not subject to the kind of over-grazing that often happens on modern rangelands. These natural wilderness areas stored massive amounts of carbon in the vegetation and soils. Furthermore, much forest land has been cleared for grazing. And today's farm animals are fed feed crops to a large extent. Cattle that are fed corn emit far more methane than when they eat their natural diet of grass.

For more on this issue also see our in depth article: Climate change: The inconvenient truth about what we eat.