Four new man-made gases which contribute to destruction of the ozone layer have been identified by scientists.
An estimated 74,000 tons of three chlorofluorocarbons (CFCs) and one hydrochlorofluorocarbon (HCFC) have been released into the atmosphere within recent decades, the research led by the University of East Anglia (UEA) found.
All four gases started to enter the atmosphere in the 1960s, suggesting they are entirely man-made, and two are significantly increasing, the research revealed.
Emission increases on this scale have not been seen for other types of CFCs – the main cause of the hole in the ozone layer discovered above Antarctica – since controls on the gases were introduced in the 1990s, the scientists said.
But they are nowhere near the peak emissions of CFCs of around a million tons a year seen in the 1980s, before action to tackle the problem was taken.
Controls on CFCs to preserve ozone in the stratosphere that protects life on earth by absorbing harmful ultraviolet radiation from the sun came into force under the Montreal Protocol in 1989, with a total global ban implemented by 2010.
Although the research does not pinpoint where the gases are coming from, it appears they are from the northern hemisphere
Scientists identified the new gases by analysing air samples from unpolluted Tasmania between 1978 and 2012, and comparing modern air samples with air trapped in polar ‘firn’ snow, which provides a natural archive of the atmosphere dating back a century.
Johannes Laube, from UEA’s School of Environmental Sciences, 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.”
He said the laws to reduce and phase out CFCs, followed by the total ban, had successfully cut the production of many such compounds on a global scale, but legislation loopholes still allowed for some use under certain exemptions.
“The identification of these four new gases is very worrying as they will contribute to the destruction of the ozone layer.”
Although the research does not pinpoint where the gases are coming from, Laube said it appeared they were from the northern hemisphere.
He added: “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.”
But he said he hoped that by detecting and highlighting the new gases very early, it would be possible to address the problem, and that the loopholes in the Montreal Protocol could be tightened.
Commenting on the research, William Collins, professor of meteorology at the University of Reading, said: “Although these new emissions are small, contributing a fraction of a per cent of the total emissions of ozone depleting substances, for the Montreal Protocol to continue to be successful it is necessary to understand whether it is being strictly complied with.
“This study provides useful new information on policing the Montreal Protocol, tracing sources of new CFCs that are possibly arising as the by-products of manufacturing other chemicals.”
Martyn Chipperfield, professor of atmospheric chemistry at the University of Leeds, said: “While these newly discovered gases can, in theory, cause some damage to the ozone layer, their combined abundance is over 500 times smaller than that of the main ozone-destroying compounds in the 1990s.”