Source of new CFC emissions discovered

Since 2013, annual emissions of the banned chlorofluorocarbon CFC-11 have increased by around 7,000 metric tons from eastern China, according to a new study by an international team of scientists including Empa researchers, published in «Nature» today. The new discovery follows a finding in 2018 that emissions of this very important ozone-depleting substance had increased. This surprise finding indicated to researchers and policy makers around the world that someone somewhere was likely producing and emitting thousands of metric tons of this substance, despite a global phase-out since 2010 under the Montreal Protocol (see box). Matt Rigby, a lead author of the study of the University of Bristol, says: "Through global monitoring networks such as the Advanced Global Atmospheric Gases Experiment ( AGAGE ) and the National Oceanic and Atmospheric Administration Global Monitoring Division ( NOAA GMD ), scientists have been making measurements of CFCs in the atmosphere for over 40 years. In recent decades, we've primarily seen declining CFC emissions reflected in these measurements because of the Montreal Protocol. Therefore, it was unexpected when it was reported last year that, starting around 2013, global emissions of one of the most important CFCs suddenly began to grow." This finding was concerning because CFCs are the main culprits in depletion of the stratospheric ozone layer, which protects us from the sun's ultraviolet (UV) radiation. Any increase in emissions of CFCs will delay the time it takes for the ozone layer, and the Antarctic ozone "hole", to recover. But where were these new emissions coming from?