A synthetic chemical widely used in the manufacture of computers and flat-screen televisions is a potent greenhouse gas, with 17,000 times the global warming effect of carbon dioxide, but it has never been measured in the atmosphere or regulated by international treaty.

The chemical, nitrogen trifluoride (NF3) could be considered the "missing greenhouse gas," atmospheric chemists Michael J. Prather and Juno Hsu of the University of California, Irvine, wrote in a paper released June 26 in the journal Geophysical Research Letters. "With the surge in flat panel displays, the market for NF3 has exploded."

The rapid growth in the production of the once-obscure substance is raising alarm among some climate scientists. Once emitted into the atmosphere, it has a life of 550 years, according to calculations by Prather and Hsu.

When the Kyoto Protocol, the 1997 international global warming treaty, was negotiated to control the rapid rise of planet-warming gases, NF3 was a niche product used in modest amounts in the semi-conductor industry.

At the time, computer chip manufacturers used perfluorocarbons to clean the vacuum chambers where integrated circuits were made. But about two-thirds of the chemicals escaped into the atmosphere, contributing to the greenhouse effect, a warming of the Earth's surface.

Reacting to environmental concerns, the industry sought a substitute &

and estimated that NF3, though it had greater potential for global warming, was less likely to escape into the air. "We moved into manufacturing NF3 for environmental reasons," said Corning F. Painter, vice president of global electronics for Air Products, the world's leading producer. The Allentown, Pa., company received a 2002 "Climate Protection Award" from the Environmental Protection Agency for its transition.

Last year, it announced a major production expansion at its U.S. and Korean plants. About three quarters of the chemical is now used to manufacture computer microchips; the rest is used to make liquid crystal display panels on flat-screen televisions, Painter said.

Overall, world production of NF3 is likely to reach 8,000 tons a year by 2010, Painter said.That is the equivalent of more than 130 million metric tons of carbon dioxide. comparison, according to the UC Irvine paper, a major coal-fired power plant, producing 3,600 megawatts of electricity emits as much as 25 million metric tons of carbon dioxide a year.

Air Products officials say that about 2 percent of NF3 is emitted during manufacturing and much of that is burned off before reaching the atmosphere.

But Prather, a leading author of the influential reports of United Nations' Intergovernmental Panel on Climate Change, cited a study showing that even "under ideal conditions," more than — percent may be emitted. And, he added, "a slippery gas" such as NF3 could easily leak out undetected during manufacture, transport, application or disposal.

"We don't know if — percent is getting out or 20 percent is getting out. ... But once you let the genie out of the bottle, you can't get it back in."

Prather said that UC Irvine researchers were working on a method to measure concentrations of the gas in the atmosphere, so that industry emissions estimates are not the only source of information.

Atmospheric scientists not connected with the paper praised the authors for raising a significant issue for future climate negotiations. "NF3 lives a very long time in the atmosphere," said Charles E. Kolb Jr., an IPCC scientist with Massachusetts-based Aerodyne Research Inc. "We are having a hard enough time controlling carbon dioxide and methane &

we shouldn't be creating a new problem."

Another climate scientist, V. (Ram) Ramanathan of UC San Diego, noted the potency and long-life of NF3, adding "This paper raises new awareness of this molecule. We need to know how much of these super-greenhouse gases are up there." The Kyoto protocol covered six greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, PFCs and sulphur hexafluoride.

California, citing the danger of water shortages, wildfires and other effects of climate change, last month adopted a draft plan to control global warming emissions statewide, including several synthetic greenhouse gases but not NF3. "The larger issue is the chlorofluorocarbons and hydrochlorofluorocarbons," said state air resources board spokesman Stanley Young.

"Enough material (is) stored in old refrigerators, air conditioners and insulating foams to equal over 600 million metric tons of carbon dioxide in California alone."