America’s total greenhouse gas emissions actually fell 3.4 percent over the course of 2012, according to the LA Times.
“The decline over the previous year was driven mostly by power plant operators switching from coal to natural gas,” the LA Times reported, as well as by “improvements in fuel efficiency for transportation and a warmer winter that cut demand for heating.”
The report pulls from an annual greenhouse gas (GHG) inventory released by the Environmental Protection Agency — and the 2012 edition came out Tuesday. It shows the country’s GHG emissions peaked in 2007, at 7,325 million metric tons, and then fell. It hit 6,526 million metric tons in 2012, putting it 10 percent below 2005 levels. The 2012 number is also within a stone’s throw of the 6,233 million metric tons released in 1990 — the first year the inventory was taken.
CREDIT: Environmental Protection Agency
Eighty-two percent of the emissions were carbon dioxide; 9 percent of the emissions were from methane; 6 percent were nitrous oxide; and 3 percent were fluorinated gases such as hydrofluorocarbons — particularly potent GHGs that the U.S., China, and other major countries have sought to crack down on in recent years.
Methane poses a potential hazard: it is the major component in natural gas, and some of it inevitably leaks from the industry’s infrastructure. Like hydrofluorocarbons, methane traps much more heat on a pound-for-pound basis than carbon dioxide, and multiple studies suggest EPA’s measurements severely undercount the scale of the leakage. If that’s correct, then methane’s contribution to America’s GHG problem is more than enough to wipe out any advantage to natural gas in terms of avoiding climate change.
Also on the bad news front: an initial estimate by the U.S. Energy Information Administration, released in January, anticipated that national carbon dioxide emissions ticked back up by 2 percent in 2013. The reversal was largely due to a rise in natural gas prices — which may not be temporary — that shifted some utilities back to burning coal.