Newly discovered man-made gases pose threat to ozone layer
Four newly-detected gases are depleting the ozone in the atmosphere, and humans are to blame, according to the results of a study published in the journal Nature Geoscience on March 9.
"'Ozone depleting substances emitted through human activities cause large-scale damage to the stratospheric ozone layer and influence global climate," according the research team led by Johannes C. Laube of the Centre for Ocean and Atmospheric Sciences at the University of East Anglia in the UK. "Consequently, the production of many of these substances has been phased out — prominent examples are the chlorofluorocarbons, or CFCs, and their intermediate replacements, the hydrochlorofluorocarbons, or HCFCs."
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Until now, seven types of CFCs and six types of HCFCs were shown to contribute to destruction of the ozone layer. The four newly discovered damaging gases consist of three CFCs and one HCFCs.
"CFCs are the main cause of the hole in the ozone layer over Antarctica. Laws to reduce and phase out CFCs came into force in 1989, followed by a total ban in 2010. This has resulted in successfully reducing the production of many of these compounds on a global scale," said Laube in a report on the findings published by the University of East Anglia. "However, legislation loopholes still allow some usage for exempted purposes."
Even as the global community has taken steps toward limiting the destruction of the ozone layer, mankind, it seems, has new ways to cause environmental damage. "Our research has shown four gases that were not around in the atmosphere at all until the 1960s, which suggests they are man-made," said Laube. The sources of the newly-found gases are unknown, which means investigation is necessary, he said. "Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components," said Laube. "What's more, the three CFCs are being destroyed very slowly in the atmosphere — so even if emissions were to stop immediately, they will still be around for many decades to come,
The four new gases have been identified as CFC-112, CFC-112a, CFC-113a and HCFC-133a. CFC-113a has been listed as an "agrochemical intermediate for the manufacture of pyrethroids", a type of insecticide once widely used in agriculture. CFC-113a and HCFC-133a are intermediaries in the production of widely used refrigerants.
Researchers made the discovery by analyzing unpolluted air samples collected in Tasmania between 1978 and 2012. They based their findings on the extraction of deep firn snow, the perennial snow pack, in Greenland in 2008, using gas chromatography with mass spectrometric detection. Air extracted from this snow is a natural archive of the contents of the atmosphere up to 100 years ago, according to the BBC.
Scientists from the British Antarctic Survey were the first to discover a huge hole in the ozone over Antarctica in 1985. Research found it was caused by CFC gases, invented in the 1920s for use in refrigerants and as aerosol propellants in products such as hairspray and deodorant. Rapid global action was taken to limit the substance, and in 1987, the Montreal Protocol went into effect.
According to NASA, the ozone hole over Antarctica was slightly smaller in 2013 than the average for recent decades, based on data from the Ozone Monitoring Instrument on NASA's Aura satellite and the Ozone Monitoring and Profiler Suite on the NASA-NOAA Suomi NPP satellite. The average size of the hole from September to October 2013 was 21 million square kilometers, or 8.1 million square miles. The average size since the mid-1990s was 22.5 million square kilometers, or 8.7 million square miles. The single-day maximum area reached 24 million square kilometers, or 9.3 million square miles, on Sept.16, 2013, an area about the size of North America.
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