Four ozone-depleting man-made gases identified
An estimated 74,000 tonnes of three chlorofluorocarbons (CFCs) and one hydrochlorofluorocarbon (HCFC) have been released into the atmosphere in recent decades, the research led by the University of East Anglia 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. However, they are no where near the peak emissions of CFCs of around 1m tonnes 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.
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 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,” said Dr Laube.
“We don’t know where the new gases are being emitted from and this should be investigated. Possible sources include feedstock chemicals for insecticide production and solvents for cleaning electronic components.”
Although the research does not pinpoint where the gases are coming from, Dr Laube said it appeared they were from the northern hemisphere.
“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,” said Dr Laube.
However, he said he hoped that, by detecting and highlighting the new gases very early, it would be possible to address the problem, and that loopholes in the Montreal Protocol could be tightened.
William Collins, professor of meteorology at the University of Reading, said: “Although these new emissions are small, contributing a fraction of a percent 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.
