China is behind the puzzling increase in annual emissions of the banned chlorofluorocarbon (CFC), with new satellite imagery showing eastern China responsible for the majority of the 7,000 tonnes emitted into the atmosphere.
The findings come a year after a surge in CFC emissions was recorded, confusing scientists following the 2010 phase out of the dangerous chemical under the Montreal Protocol.
The University of Bristol’s Dr Matt Rigby lead the research into the puzzling emissions of CFC.
"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 chlorofluorocarbons (CFCs) in the atmosphere for over 40 years,” Dr Rigby said.
"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 ultra-violet 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? Until now, researchers only had an indication that at least part of the source was located somewhere in eastern Asia.
"Initially our monitoring stations were set up in remote locations, far from potential sources," said Ron Prinn, co-author of the new study, leader of the AGAGE network and professor at the Massachusetts Institute of Technology (MIT).
"This was because we were interested in collecting air samples that were representative of the background atmosphere, so that we could monitor global changes in concentration and determine their atmospheric lifetimes."
The full report, published in the Nature International Journal of Science, can be found here