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.
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.
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.
SOURCE: Environment News Service (ENS)
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