For the good of the planet, we’re all being asked to reduce our carbon footprints — the quantities of greenhouse gases, aka GHGs, associated with our actions, writes Janet Raloff for Science News.

According to Science News, Ulf Sonesson of the Swedish Institute for Food and Biotechnology in Goteborg was one of the speakers on a panel titled “Food for Thought” at the American Association for the Advancement of Science annual meeting. The speakers shared data from largely new analyses on how foods, production techniques, and transportation affect the climate costs associated with dining choices. And there were some big surprises, says the report.

No longer a surprise is the relative energy intensity associated with meat, especially beef. For instance, roughly half of the GHG emissions due to human diets come from meat even though beef, pork and chicken together account for only about 14 per cent of what people eat.

From a climate perspective, beef is in a class by itself. It takes a lot of energy and other natural resources to produce cattle feed, manage the animals’ manure (a major emitter of methane, a potent GHG), get the livestock to market, slaughter the animals, process and package the meat, dispose of the greater part of the carcass that won’t be human food, market the retail cuts, transport them home from the store, refrigerate them until dinner time, and then cook the beef.

Tally the GHG emissions associated with all of those activities, Sonesson says, and you’ll find it’s the global-warming equivalent to spewing 19 kilograms of carbon dioxide for every kg of beef served. Swine are more environmentally friendly. It only takes about 4.25 kg of CO2 to produce and fry each kg of pork.