More Ozone-Depleting Chlorofluorocarbons Detected In Atmosphere

Once widely used as refrigerants, propellants, and solvents, chlorofluorocarbons (CFCs) released to the atmosphere cause the destruction of Earth’s protective ozone layer. Their prevalence has declined in the past two decades because of an international treaty to control their use. Nevertheless, researchers recently detected three CFCs and one hydrochlorofluorocarbon not previously observed in the atmosphere, reports an international group led by Johannes C. Laube of the University of East Anglia, in England (Nat. Geosci. 2014, DOI: 10.1038/ngeo2109). The compounds turned up in air and snow. Concentrations of two of the species—CFCl₂CFCl₂ and CF₂ClCCl₃—increased in the atmosphere from the 1970s to the mid-1990s, then began to slowly decrease, similar to previously tracked CFCs controlled by the treaty. Concentrations of two others, however—CF₃CCl₃ and CF₃CH₂Cl—continued to increase through 2012, when the study’s sampling ended. No data are available to pinpoint the origins of the still-increasing compounds, which are intermediates in refrigerant production; CF₃CCl₃ is also an insecticide feedstock. Although emissions of the compounds are far less than peak CFC emissions in the 1980s, their increases suggest that their sources should be investigated, Laube and colleagues say.