How Much Does Ag Contribute to Greenhouse Gases

Ezra Klein in the Post last week used 18 percent. Today the Meat Institute wrote a letter to the editor, saying Klein was using a global figure, which didn't apply to US emissions;

The Environmental Protection Agency concluded that in 2007, only 2.8 percent of U.S. greenhouse gas emissions came from animal agriculture.

Meanwhile, at farmgate, I get this:

Agriculture contributes 6.7% of the total greenhouse gases emitted by the US, but the legislation so far does not penalize agriculture.

And Tom Philpott at Grist provides a useful explanation of the discrepancy between Klein and the Meat people (different denominators, different things included) and provides this ending:

So if Boyle’s 2.8 percent figure is off the mark, what percentage of U.S. greenhouse gas emissions does actually stem from meat production? Loglisci of The Center for a Livable Future says it’s hard to pinpoint. “As far as I know, no one has crunched the numbers to determine a comparable GHG emissions number for U.S. livestock,” he writes.

Working with a Johns Hopkins researcher, Loglisci compiled some rough numbers and came out with an estimate of about 9 percent—half of the global FAO number cited by Klein, but three times the figure pushed by Boyle. “And in real numbers, not percentages, U.S. livestock production’s GHG contribution could still be the largest in the world,” Loglisci writes.