A greenhouse gas 17,000 times more potent than carbon dioxide is more widespread in the atmosphere than previously thought.
Researchers say that in 2006 there were 4,200 metric tons of nitrogen trifluoride (NF3) in the air instead of the estimated 1,200 metric tons. And there is now 5,200 metric tons of it in the atmosphere, according to a research team led by Ray Weiss of the Scripps Institution of Oceanography in La Jolla, Calif.
NF3 is used primarily in manufacturing semiconductors, but is also involved in the production of flat panel LCDs and thin film photovoltaic cells. It's used as a chamber cleaning gas, not an actual part of products, and manufacturers try to destroy as much of it as possible after it has been used.
Industries switched to NF3 as a replacement for perfluorocarbon gases since it has a shorter lifespan (550 years compared to 10,000-50,000 years) and it was estimated that less of NF3 was emitted during manufacturing, even though NF3 has a higher global warming potential.
Previous estimates said that 2 percent of the gas is emitted when used. Weiss' research says, though, that 16 percent of the estimated 4,000 metric tons of NF3 produced a year is being emitted.
Although NF3 is stronger and longer lasting than carbon dioxide, it accounts for 0.04 percent of the global warming effect caused by human-produced carbon dioxide emissions, according to Weiss' research. But Weiss says that impact needs to be kept small, and the gas should be included in the Kyoto Protocol. "Otherwise an artificial incentive is created to emit NF3 in place of the perfluorocarbons despite its higher global warming potential, and its effect could grow to a much greater value than it is at present," he said. NF3 is not covered in the 1997 Kyoto Protocol with other greenhouse gases because its emissions were considered so low at the time.
Weiss and his team got their figures by looking at air samples from California and Tasmania from the past 30 years gathered by the NASA-funded
Advanced Global Atmospheric Gases Experiment. Concentrations of NF3 went from 0.02 parts per trillion in 1978 to 0.454 parts per trillion in 2008, with higher concentrations found in the Northern Hemisphere, where the gas is primarily used. According to a
new report on the global market for NF3 also released this month, the Asia-Pacific region holds a 67.3 percent share in the NF3 market due to the semiconductor industry being concentrated in that area.
Weiss' full research will be published at the end of this month in
Geophysical Research Letters. Earlier this year, researchers from the University of California
published a report on the impact of NF3, calling for research into how much of the gas is in the air and arguing for its inclusion in the Kyoto Protocol.
