New research from the National Oceanic and Atmospheric Administration in Boulder suggests there are new sources of a banned ozone depleting chemical.
"The reduction in the atmospheric concentration of trichlorofluoromethane (CFC-11) has made the second-largest contribution to the decline in the total atmospheric concentration of ozone-depleting chlorine since the 1990s", the new research says. A smaller amount of CFC11 also exists today in older refrigerators and freezers. However, that decrease is significantly slower than it would be without the new CFC emissions. After considering a number of possible causes, Montzka and his colleagues concluded that CFC emissions must have increased after 2012.
Measurements from Hawaii indicate the sources of the increasing emissions are likely in eastern Asia. "This suggests unreported new production".
As a result of the controls, CFC11 concentrations have declined by 15% from peak levels measured in 1993.
Emissions of CFC-11 increased by 25 percent in 2012, despite the fact that the chemical substance is part of a group of pollutants for ozone, which were banned under the Montreal Protocol of 1987.
"We're raising a flag to the global community to say, 'This is what's going on, and it is taking us away from timely recovery of the ozone layer", said NOAA scientist Stephen Montzka, the study's lead author.
"This is the first time that emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since production controls took effect in the late 1980s", they note.
If the source of these new emissions can be identified and controlled soon, the damage to the ozone layer should be minor, Montzka said.
But Mr. Doniger noted that the Montreal Protocol, which has been signed by almost 200 countries, has a strong track record of compliance, with countries often reporting their own violations.
Keith Weller, a spokesman for the United Nations Environment Program, which helps implement the protocol, said the findings would be presented to the parties to the agreement for review.