Nitrogen trifluoride in the global atmosphere

[1] Background atmospheric abundances and trends of nitrogen trifluoride (NF₃), a potent anthropogenic greenhouse gas, have been measured for the first time. The mean global tropospheric concentration of NF₃ has risen quasi-exponentially from about 0.02 ppt (parts-per-trillion, dry air mole fraction) at the beginning of our measured record in 1978, to a July 1, 2008 value of 0.454 ppt, with a rate of increase of 0.053 ppt yr⁻¹, or about 11% per year, and an interhemispheric gradient that is consistent with these emissions occurring overwhelmingly in the Northern Hemisphere, as expected. This rise rate corresponds to about 620 metric tons of current NF₃ emissions globally per year, or about 16% of the poorly-constrained global NF₃ production estimate of 4,000 metric tons yr⁻¹. This is a significantly higher percentage than has been estimated by industry, and thus strengthens the case for inventorying NF₃ production and for regulating its emissions.