Potent New Greenhouse Gas Discovered

MAINZ, Germany, July 31, 2000 (ENS) - Researchers from seven institutions in Germany, the United Kingdom and the United States have detected a previously unreported compound of industrial origin in the atmosphere - trifluoromethyl sulphur pentafluoride (SF5CF3). It is considered the most potent greenhouse gas measured to date.

There is no doubt that the new gas SF5CF3 is made by industry, or is produced during certain processes involving industrial gases, but its exact source remains a mystery.

Antarctica

Analysis of Antarctic snow revealed a new greenhouse gas, SF5CF3. (Photo courtesy National Renewable Energy Lab)
The increase of this peculiar gas in the atmosphere is coupled with the increase of the very inert gas sulfur hexafluoride (SF6), suggesting a common source, according to their article in the journal "Science," a publication of the American Association for the Advancement of Science.

Emissions of sulfur hexafluoride (SF6) are governed by the Kyoto Protocol, an addition to the United Nations climate change treaty. It is one of the six greenhouse gases linked to global warming.

The new greenhouse gas was discovered by scientists at the Max Planck Institute for Chemistry in Mainz, Germany, working with researchers from the School of Environmental Science at University of East Anglia in the UK; Ford Motor Company, USA; University of Reading, UK; Natural Environment Research Council in Cambridge, UK; and the University of Frankfurt working with scientists from the British Antarctic Survey.

The scientists speculate that SF5CF3, which is closely chemically related to SF6, originates as a breakdown product of SF6 in high voltage equipment.

SF6 is used in electrical switches to suppress sparks, in protecting metals during a melting process, in tennis balls, car tires and even at one stage in running shoes. Due to its good insulation properties it was also used as a noise barrier in double glazed window panes.

switches

High voltage direct current transmission at the Celilo substation, part of the Bonneville Power Administration. SF5CF3 is a breakdown product of the gas SF6 in high voltage equipment. SF6 is used to electrically insulate high voltage components. (Photo courtesy Oak Ridge National Laboratory)
SF6 is a strong greenhouse gas and the molecule is very resistant against attack in the atmosphere. The natural self cleansing property of the atmosphere is insufficient to deal with such super molecules. It has a long lifetime, and being a strong greenhouse gas, its production is now restricted under the Kyoto Protocol.

The new molecule SF5CF3 is even a stronger greenhouse gas. Measurements of its infrared absorption cross section revealed the largest radiative forcing, on a per molecule basis, of any gas found in the atmosphere to date, the discoverers report. It has a long lifetime - somewhere between several hundred and a few thousand years.

The researchers found this new gas while conducting expeditions in Antarctica to extract air samples from the thick firm layers of snow.

These layers, up to 100 meters thick, contain old air, sometimes from the beginning of the last century, according to Carl Brenninkmeijer of the Max Planck Institute.

"This air has been extensively analyzed in our institute and in Norwich, England. The new gas was discovered at extremely low concentrations," he said.

"Without even knowing it, we have been releasing a very potent greenhouse gas for almost 50 years. We have to find the source of this gas and to try to stop its increase," Brenninkmeijer said.