March 12, 2009 / 5:05 AM / 10 years ago

Termite-killer is powerful greenhouse gas -study

By David Fogarty, Climate Change Correspondent, Asia

SINGAPORE, March 12 (Reuters) - A compound used to kill termites and other pests has turned out to be a potent greenhouse gas that stays in the atmosphere much longer than previously thought, an international team of scientists has found.

Sulfuryl fluroide (SO2F2) is nearly 5,000 times more effective at warming the atmosphere than an equal volume of carbon dioxide, scientists say.

The SO2F2 findings come just months after similar research found that another powerful greenhouse gas used in the electronics industry was more abundant than previously thought.

Sulfuryl fluoride is used to fumigate buildings and was created to replace methyl bromide, which attacks the Earth’s ozone layer.

Study leader Jens Muehle, an atmospheric chemist at Scripps Institution of Oceanography, in La Jolla, California, said he started detecting an unknown compound in air samples in early 2004.

A team of researchers expanded the analysis to air samples routinely collected around the world at stations of the NASA-funded Advanced Global Atmospheric Gases Experiment network and to old air samples archived in metal cylinders.

They found that the gas remained in the atmosphere about 36 years, six to ten times longer than previously thought. The study appears in the March 12 Journal of Geophysical Research, a publication of the American Geophysical Union.

The concentration of the gas also rose 4 to 6 percent per year between 1978 and 2007, to a global atmospheric level of about 1.5 parts per trillion by the end of 2007, the study says.

"SO2F2 wasn’t recognised as an important greenhouse gas," Paul Fraser, one of the report’s authors, told Reuters. About 2,000 tonnes of the gas are emitted annually.

"They thought it had a short life-time and recent work has shown it’s quite long and that changes its impact on the environment completely. So now it’s recognised as a potent greenhouse gas," said Fraser, of Australia’s state-backed Commonwealth Scientific and Industrial Research Organisation.

But he doubted it would be included in the broader climate pact being negotiated to replace the Kyoto Protocol, given it was already a replacement gas for the ozone-damaging methyl bromide.

Last year, scientists from Scripps found that the levels of nitrogen trifluoride (NF3), used to etch silicon wafers and to make plasma televisions, were four times higher than previously thought and rising rapidly.

NF3 is 17,200 times more powerful a greenhouse gas than CO2 and stays in the atmosphere for hundreds of years. About 600 tonnes of the colourless gas are emitted each year.

Fraser said nitrogen trifluoride’s concentration in the atmosphere was only about 1 part per trillion but was increasing by 11 percent a year and was likely to be included in the next U.N. climate pact to fight global warming. (Editing by Valerie Lee)



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