It's a silent but deadly source of greenhouse gases that contributes more to global warming than the entire world transportation sector, yet politicians almost never discuss it, and environmental lobbyists and other green activist groups seem unaware of its existence.
That may be because it's tough to take cow flatulence seriously. But livestock emissions are no joke.
Most of the national debate about global warming centers on carbon dioxide, the world's most abundant greenhouse gas, and its major sources -- fossil fuels. Seldom mentioned is that cows and other ruminants, such as sheep and goats, are walking gas factories that take in fodder and put out methane and nitrous oxide, two greenhouse gases that are far more efficient at trapping heat than carbon dioxide. Methane, with 21 times the warming potential of CO2, comes from both ends of a cow, but mostly the front. Frat boys have nothing on bovines, as it's estimated that a single cow can belch out anywhere from 25 to 130 gallons of methane a day.
It isn't just the gas they pass that makes livestock troublesome. A report from the United Nations Food and Agriculture Organization identified livestock as one of the two or three top contributors to the world's most serious environmental problems, including water pollution and species loss. In terms of climate change, livestock are a threat not only because of the gases coming from their stomachs and manure but because of deforestation, as land is cleared to make way for pastures, and the amount of energy needed to produce the crops that feed the animals.
All told, livestock are responsible for 18% of greenhouse-gas emissions worldwide, according to the U.N. -- more than all the planes, trains and automobiles on the planet. And it's going to get a lot worse. As living standards rise in the developing world, so does its fondness for meat and dairy. Annual per-capita meat consumption in developing countries doubled from 31 pounds in 1980 to 62 pounds in 2002, according to the Food and Agriculture Organization, which expects global meat production to more than double by 2050. That means the environmental damage of ranching would have to be cut in half just to keep emissions at their current, dangerous level.
It isn't enough to improve mileage standards or crack down on diesel truck emissions, as politicians at both the state and national levels are working to do. Eventually, the United States and other countries are going to have to clean up their agricultural practices, while consumers can do their part by cutting back on red meat.
Burgers
A typical beef cow produces approximately 500 lbs of meat for boneless steaks and ground beef. By regulation, a beef cow must be at least 21 months old before going to the slaughterhouse; let's call it two years. A single cow produces 114 kilos of methane per year in eructations and flatulence, so over its likely lifetime, a beef cow produces 228 kilos of methane (not including the methane from its manure). Since a single kilo of methane is the equivalent of 23 kilos of carbon dioxide, a single beef cow produces 5244 CO2-equivalent kilograms of methane over its life. If we assume that the typical burger is a quarter-pound of pre-cooked meat, that's 2,000 burgers per cow. Dividing the methane total by the number of burgers, then, we get about 2.6 CO2-equivalent kilograms of additional greenhouse gas emissions from methane, per burger, or about 5-10 times more greenhouse gas produced from cow burps than from all of the energy used to raise, feed or produce all of the components of a completed cheeseburger!
At 2.85-3.1 kg of CO2 (equiv) per burger, then, that's 428-465 kg of greenhouse gas per year for an average American's burger consumption.
