(Mysterious compounds undermining recovery of giant ozone hole over Antarctica, scientists warn
The new research, published the journal Nature Geoscience, analysed air samples captured since the mid-1970s in several ways. Air bubbles trapped in snowpack in Greenland, samples taken by scientists in Tasmania and others collected by aircraft flying 13 miles above Europe were all analysed. The team found three new CFCs and one HCFC, none of which had been identified before. "I was surprised no-one had picked these up before," said Laube. At least 74,000 tonnes of the four newly discovered chemicals have been emitted, the scientists estimate, although in the 1980s one million tonnes of other CFCs were pumped into the atmosphere every year.
Despite the production of all CFCs having been banned since 2010, the concentration of one – CFC113a – is rising at an accelerating rate. The source of the chemicals is a mystery but Laube suggests that CFC113a may be being used as a feedstock chemical in the production of agricultural pesticides. "But we can't rule out illegal sources," he said.
"Although these new emissions [of the four chemicals] are small, for the Montreal protocol to continue to be successful it is necessary to understand whether it is being strictly complied with," said Prof William Collins, at the University of Reading, and not part of the research team. "This study provides useful new information on policing the protocol, tracing sources of new CFCs that are possibly arising as the by-products of manufacturing other chemicals."