Says U.S. greenhouse gas "emissions are at 20-year lows."
U.S. Rep. Joe Barton, R-Texas, in a tweet
Perry Lindstrom, an economist with the Energy Information Administration, emailed us a spreadsheet indicating that the nation's energy-related carbon dioxide emissions were estimated at 1,339 metric tons in the first quarter of 1992 and at a slightly higher amount, 1,344 metric tons, for the comparable months of 2012. In the intervening years, first-quarter emissions topped out at 1,580 metric tons in 2004 and bottomed out at 1,364 metric tons in 1993, according to the spreadsheet.
However, Lindstrom said he would hesitate to reach conclusions solely by comparing emissions in part of a year to emissions in part of another year in contrast to looking, say, decade to decade. At our request, he provided a spreadsheet comparing energy-related carbon dioxide emissions for the 10 months through October 2012 to such emissions over the comparable part of each previous year over two decades.
According to this spreadsheet, the estimated emissions from January through October 2012, 4,386 metric tons, were the lowest 10-month total since 1995 — 17 years earlier — when such emissions totaled 4,385 metric tons.
Mindful that Barton's tweet said greenhouse gas emissions were at a 20-year low, we looked next at emissions of methane, nitrous dioxide, sulfur dioxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride as estimated in the Environmental Protection Agency's April 2012 inventory of U.S. greenhouse gas emissions — the latest inventory that would have been available when Barton tweeted.
It indicates that total emissions of three gases were higher in 2010 than 1990, while emissions of four others were lower.
In keeping with Barton's 20-year window, we used the inventory figures to gauge the difference between estimated emissions of each greenhouse gas in 2010 and 1990:
• Carbon dioxide emissions in 2010 were 12 percent greater than in 1990.
• Methane emissions were lower by 0.3 percent.
• Nitrous oxide emissions were lower by 3 percent.
• Hydrofluorocarbon emissions were higher by more than 200 percent.
• Perfluorocarbons were lower by 73 percent.
• Sulfur hexafluoride emissions were lower by 57 percent.
Taking all the greenhouse gases into account, according to the inventory, overall emissions were 11 percent higher in 2010 than 1990 — and also up 3 percent from 2009, when total emissions dipped considerably during the national recession. Aside from 2009, the previous year with lower greenhouse gas emissions than 2010 was 1997, according to the inventory.
We rate this claim Mostly False.
Edited for print. Read the full version at PolitiFact.com.