It can only get warmer

Scientists discover a greenhouse gas that is several times more dangerous than carbon dioxide

Published: Monday 15 May 2000

Researchers in the US and Europe have made an alarming discovery -- a greenhouse gas which is 18,000 to 22,000 times more powerful than carbon dioxide (CO 2 ) and with an atmospheric life estimated at 3,500 years.

The findings were recently presented by Ole John Nielsen of the Chemical Institute at Copenhagen University at a conference on greenhouse gases conducted by the Society of Danish Engineers' chemistry group. According to the results of the research, the gas trifluoromethylsulphur pentafluoride or SF5CF3 is present in the atmosphere at a height of eight to 32 kilometres above the Earth's surface. The SF5CF3 was first detected during an analysis of stratospheric air samples when an unexpected reading was found close to sulphur hexafluoride or SF6, a more common industrial gas.

SF6 and SF5CF3 share one common characteristic in that they both can absorb heat radiating from the Earth's surface, a trait that classifies them as greenhouse gases. Both gases have been found to exist in deep snow in remarkably similar concentrations. But, since the concentration of SF6 in the atmosphere has been measured for years, researchers conclude that SF5CF3 concentrations have increased from nothing in the late 1960s to 0.12 parts per trillion -- 10 to power of 12 -- in 1999.

Commenting on the latest discovery, one of the researchers of the Ford Motor Company's chemical laboratories says, "We don't know where SF5CF3 comes from, which is worrying. But it must be connected with human activity." Researchers think the new gas may be a by-product of the manufacture or decomposition of SF6, an electrical insulator in transformers and similar high-voltage electrical equipment.

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