Livestock sector spews a fifth of human-caused greenhouse-gas emissions, says U.N.

The U.N. has issued fresh content on a vital cause of global warming: cow farts. It seems that 18 percent of human-caused greenhouse gases stem from farm animals and the livestock industry, according to the U.N. Food and Agriculture Organization. Besides poots, agriculture-related deforestation and energy use contribute to the total. When all the carbon-equivalent math is said and done, livestock produce more of the world’s human-caused greenhouse-gas emissions than cars, says the U.N.: about 9 percent of carbon dioxide, up to 40 percent of methane, and nearly two-thirds of nitrous oxide. If those numbers don’t mooove you, consider that global meat and milk production is projected to roughly double by mid-century. To address livestock’s effect on global warming (not to mention water pollution and biodiversity) the report proposes using manure as fuel, increasing irrigation efficiency, improving land use, and changing animals’ diets to reduce flatulence. Which does not make us grin.