New ozone-depleting gases found in atmosphere
Mar 15 BTI
Worried scientists said Sunday they had found four new
ozone-destroying gases in the atmosphere, most likely put there by
humans in the last 50-odd years despite a ban on these dangerous
compounds.It is the first time since the 1990s that new substances
damaging to Earth's stratospheric shield have been found, and others may
be out there, they said.
“Our research has shown four gases that were not around in the
atmosphere at all until the 1960s, which suggests they are man-made,”
the team from Europe and Australia wrote in the journal Nature
Geoscience.They analysed unpolluted air samples collected in Tasmania
between 1978 and 2012, and from deep, compacted snow in Greenland.The
identification of these four new gases is very worrying as they will
contribute to the destruction of the ozone layer,” added a statement
from the team.
“We don't know where the new gases are being emitted from, and this
should be investigated.” Three of the gases are chlorofluorocarbons
(CFCs) a group which includes chemicals traditionally found in
air-conditioning, refrigerators and aerosol spray cans but banned under
the Montreal Protocol.
The fourth is a hydrochlorofluorocarbon (HCFC), part of a
closely-related group of compounds which replaced CFCs but are being
phased out.More than 74,000 tonnes of the four newly-identified gases
had accumulated in the atmosphere by 2012, said the team.This is very
small compared with peak emissions of CFCs in the 1980s of more than a
million tonnes per year.
“However, the reported emissions are clearly contrary to the
intentions behind the Montreal Protocol, and raise questions about the
sources of these gases,” the team wrote.Two of the gases, one CFC and
the HCFC, are still accumulating.Previously, seven types of CFC and six
of HCFC were known to contribute to ozone destruction.
CFCs, the main cause of the hole in the ozone layer over Antarctica,
are man-made organic compounds made of carbon,chlorine and fluorine.
They were phased out from 1989, followed by a total ban in
2010.HCFCs, CFC-like compounds which also include one or more hydrogen
atoms, are less ozone-damaging but contribute to climate change by
trapping more of the Sun's heat in the atmosphere.
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