The latest official estimate of the extraordinary role that livestock-rearing plays in global warming comes with a glimmer of hope: Switching over to established best practices could slash the sector's emissions by a third.
The Food and Agriculture Organization of the United Nations caused an international stir when it estimated in 2006 that livestock contributed 18 percent of the world's greenhouse gas emissions. Some critics derided the claim, saying T-bones and Big Macs couldn't possibly be so bad. The FAO has since updated its numbers, checked its facts and performed new calculations based on newer standards. The latest conclusion is little different from the earlier one: Livestock contributes 14.5 percent of worldwide emissions.
Flatulent, manure-dropping cows are by far the largest contributors to the problem. Beef production is responsible for 41 percent of the sector's emissions, and dairy farming can be blamed for 19 percent. Pig meat, poultry meat, and eggs are responsible for a little less than 10 percent apiece.
Why are cows so harsh on the climate? The same reason Auntie Flora doesn't get invited to parties: Because they belch and fart so damned much. Only the FAO doesn't say it like that. Rather, it blames the "enteric fermentation" of cattle and the methane that bovine rumination produces for 39 percent of the livestock industry's emissions.