New threats to the Ozone Layer
Scientific researchers have discovered new evidence that four man made gases are involved in the depletion of the ozone layer and two of them are present in amounts that are causing serious concern. The original fears about the ozone layer date back decades and in the mid 1980s production of chlorofluorocarbon (CFC’s) became restricted. The source of the new chemicals affecting the ozone layer however, are a mystery. The four new gases are, CFC-112, CFC-112a, CFC-113a, and HCFC 113a. CFC-113a is an ‘agrochemical intermediate for the manufacture of pyrethroids’, a category of insecticide commonly used in the agricultural industry. CFC-113a along with HCFC-133a are intermediaries commonly involved in making refrigerators. It is thought CFC-112 and 112a may be being used in producing solvents for cleaning electrical components.
The ozone layer is critical to maintaining a habitable environment on Earth and lies between 15 and 30 kilometres up in the atmosphere. The ozone layer blocks harmful Ultra Violet rays which would otherwise cause cancer and affect the reproductive capacity in animals. Scientific researchers from the British Antarctic Survey discovered a massive hole in the in he ozone layer in 1985. It was immediately agreed that the cause were CFC gases which had been invented and been in use since the 1920s. They had become widely used in propellants for products such as deodorants and hairsprays which had been used increasingly widely since the 1950s since when the effect on the ozone layer had been accumulating. Global action was almost immediate and the Montreal Protocol agreeing to restrict the use of these substances in the hope of reviving the ozone layer, was implemented in 1987. Eventually a complete world wide ban came into operation in 2010. But now new research into the ozone layer by the University of East Anglia in the UK, has unearthed evidence that four new man made gases capable of destroying the ozone layer are escaping into the atmosphere from sources yet identified. Three of the new gases are CFCs and the fourth is a hydrochlorofluorocarbon (HCFC) which is also capable of damaging the ozone layer. The scientists say that these four were not present in the atmosphere at all before the 1960s, a fact which indicates that they are likely to be man made substances. The scientific researchers discovered their newly introduced presence and potential effect on the ozone layer by doing scientific analysis of the polar snow pack. The air present in the snow contains a perfect record or what the Earth’s atmosphere would have contained at any time in the last 100 years.
The scientists compared the air extracted from the snow with up to date air samples collected in Tasmania and have estimated that around 74,000 tonnes of the offending gases have been released into the Earth’s atmosphere and are capable of damaging the ozone layer. Two of them are accumulating at a worryingly rapid rate. The concern is that eventually the gases will contribute to the destruction of the ozone layer. The main obstacle to any potential action at the moment to save the ozone layer would be the lack of information as to where the gases are coming from. Theories as to their origin include solvents used in cleaning electrical components and feedstock chemicals used to manufacture insecticides. But some scientists believe that for the sake of the ozone layer the problem has to be tackled urgently. They point out that the three CFC chemicals are destroyed very slowly in the atmosphere so even if emissions were to halt immediately they would still be present in the atmosphere for years to come and have an effect on the ozone layer. At the moment the gases are present in volumes which don’t present any serious threat to the ozone layer but may do in the future if nothing is done to restrict or eliminate further accumulation.
A job not yet done
Until these revelations emerged in March 2014 the ozone layer had dropped out of the headlines. It was considered that the Montreal Protocol had been so successful at eliminating CFCs that the threat to the ozone layer had been removed. But news about the new chemicals indicates that the ozone layer is not as yet and old story. At the moment CFC-113a seems to be causing the biggest cause for concern. But other mysteries surround the progress of the ozone layer in recent years. The hole which still appears over the Antarctic, changes in size and depth from year to year. The US Space Agency Nasa, thinks that it’s the weather rather than chemicals which is the driving force in variations in the ozone layer. They think it unlikely that chemicals are to blame for year to year fluctuations. The CFC’s which were restricted by the Montreal Protocol have now partly dissipated and the ozone layer was stating to recover. The CFCs had been damaging the ozone layer by breaking down in the upper part of the atmosphere and releasing chlorine. In reactions assisted by the Sun the chlorine systematically destroyed the ozone layer. Following the CFC ban however the hole stopped getting any bigger. But in some years, for example 2006 and 2011 the hole in the ozone layer appeared large but in 2012 it looked small. Nasa has concluded hat weather must be a driving force and is affecting the amount of ozone brought into the polar regions by the wind from year to year. Nasa has identified wind direction changes and fluctuating air temperature as influencing the amount of ozone hovering above Antarctica and so believe that weather is the cause of annual fluctuations in the apparent size of the hole in the ozone layer. Nasa thinks that these fluctuations will be the dominant feature of the hole in the ozone layer until about 2030 and after that the long lasting chemicals present in the atmosphere will start to decline steeply. They expect the ozone layer to make a full recovery by no later than 2080 and possibly sooner.
No laughing matter
The United Nations Environment Programme (Unep) has however identified yet another threat to the ozone layer. Unep thinks that the ozone layer is being depleted by nitrous oxide (laughing gas), and believes the chemical presents the biggest of the existing known threats. Scientists at Unep have concluded that owing to human activities including farming, levels of nitrous oxide might double by 2050. If that happens and the gas presents the threat to the ozone layer that Unep says it does, all of the gains already achieved by reducing CFCs could be eliminated and the ozone layer will become thinner. Thinning of the ozone layer apart from the effects identified in the mid 1980s might hasten the onset of global warming. Nitrous oxide is sometimes referred to as one of the ‘Cinderella Gases’ because its effect goes unnoticed. N2O is present naturally in the atmosphere, but agriculture is the largest man made source contributing two thirds of emissions and any effect of the ozone layer will derive from the man-made contribution. The gas is sometimes used as a painkiller and anaesthetic in surgery and dentistry. It’s sometimes used as a recreational drug called ‘nozz’ which itself is a cause for concern. Laughing gas abuse might lead to neurological damage and death. Unep believes that N2O is the third most important gas involved in potential global warming and although Nitrous Oxide makes up only 6% of greenhouse gases, its effect is the equivalent of emitting 3 billion tonnes of CO2 a year. Put in perspective this is the equivalent of half the emissions of all the motor vehicles in the world.