The latest available data show that the US continues to increase its greenhouse gas emissions. Recently released studies show that the problem could be even worse than the current data indicate, as additional substances are added to the long list of greenhouse gas culprits. However, a proposed EPA rule may begin to provide a means for obtaining better data on greenhouse gas sources, and quantities released, if the rule becomes final.
EPA's annual inventory of greenhouse gas emissions shows that the US emitted 1.4% more in 2007 than in 2006. This continues a long-running trend of increases of similar magnitude nearly every year since 1990. Emissions in the vast majority of the scores of source categories tracked either increased or remained flat for 2007. The pervasive increases make it that much harder to achieve the drastic reductions being advocated by thousands of scientists, politicians, and advocates of various stripes worldwide. The EPA report, released March 4, 2009, is a draft, and is open for public comment until April 9, 2009.
- Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007  (draft report).
The inventory doesn't include a substance that researchers from MIT, the Scripps Institution of Oceanography in San Diego, and other institutions say is 4,800 times more potent than carbon dioxide as a greenhouse gas, pound for pound. Sulfuryl fluoride is present in far smaller quantities than CO2, the dominant culprit of the 17 substances tracked internationally and by EPA, but it is increasing in the atmosphere about 5% per year. The new data show that it lasts about 36 years once released into the atmosphere, 8 times longer than previously thought.
It is being phased in as a substitute for methyl bromide, as a fumigant used in buildings and for selected agricultural crops. Methyl bromide is being phased out because it destroys ozone in the upper atmosphere. The new findings suggest to the researchers that alternatives to the alternative fumigant may be warranted. Their study was published in the March 12, 2009, Journal of Geophysical Research-Atmospheres.
A similar discovery was made by Scripps researchers in a study published Oct. 31, 2008, in Geophysical Research Letters. They found that a substance used in the electronics industry, nitrogen trifluoride, was steadily and dramatically increasing in the atmosphere. It persists for hundreds of years, and is thousands of times more potent than CO2 as a greenhouse gas, pound for pound. It may be included in future international greenhouse gas assessments.
- "Nitrogen Trifluoride in the Global Atmosphere,"  Geophysical Research Letters, October 31, 2008, by R. F. Weiss, J. Mhle, P. K. Salameh, and C. M. Harth.
In an effort to better track greenhouse gases of many types, and their sources, EPA announced on March 10, 2009, a proposed rule that is intended to provide a more detailed inventory. There would still be a substantial gap in the data, however, since the new registry wouldn't include sources that emit less than 25,000 metric tons per year (equivalent to emissions from about 4,500 passenger cars, or 2,200 homes, and a threshold that most individual small businesses wouldn't exceed, according to EPA). When added together, those smaller emitters make up about 10-15% of total emissions, according to EPA.
But the new registry would at least cover about 13,000 facilities and source categories whose emissions remain poorly documented by the current assortment of mandatory or voluntary protocols, or very limited or absent protocols for most emitters in some states. The first annual report, covering the year 2010, would be released in 2011 if the rule is finalized as is. Emissions from vehicles would be added for model year 2011 going forward. If the rule is adopted, the registry is widely anticipated to be a key tool in regulating greenhouse gas emissions in some way, since it would provide currently unavailable data on who is emitting how much.
The public comment period on the proposed rule is likely to close in mid-May 2009, 60 days after the proposed rule is published in the Federal Register, which is expected shortly  (Docket ID No. EPA-HQ-OAR-2008-0508). Included in the public comment process will be two hearings, on April 6 and 7, 2009, at the EPA Potomac Yard Conference Center in Arlington, VA, and April 16, 2009, at the Sacramento Convention Center in Sacramento, CA.