EXPERT REACTION: Mysterious rise in CFC emissions tracked to China

CFC-11 is a chlorofluorocarbon (chemical formula CFCl3) that is very stable in the lower atmosphere but rises to the stratosphere, 30 km or so above Earth's surface, where it is smashed up by radiation. The resulting  chlorine atoms cause destruction of ozone molecules (O3) in the ozone layer that stops dangerous ultraviolet radiation reaching Earth's surface and impacting on us and other species.

CFC-11 was mainly used  in 'foam blowing' - that is, the process of producing the voids in plastic foams.

Under the Montreal Protocol on substances that deplete the ozone layer, production and consumption of CFC-11 was phased out by January 1996 in developed countries, and January 2010 in developing countries, of which China is the largest. CFC-11 is still leaking out of old foams, but atmospheric concentrations have been declining.

Because it's very effective at what it does, however, there have been rogue users of old supplies and rogue producers who flout international agreements that their governments have signed up to.

Regulated production and uses of ozone-depleting substances in China, for example, have been phased out with assistance from the multinational fund that developed countries have provided. However, regulators like China EPA and some in other countries have found it difficult to deal with the rogues.

Among the authors of this international study is Dr Paul Fraser, an Australian scientist who has spent many decades studying these industrial gases that have become minor but important constituents of our atmosphere.

In Australia, CFC-11 levels are monitored at the Cape Grim Baseline Air Pollution Station in Tasmania. This data was key to deriving the global CFC-11 emissions and shows that Australian emissions, likely from old insulating foams, are not contributing to the global increase in CFC-11 emissions.

 This study highlights the importance of undertaking long-term measurements of trace gases like CFC-11 to verify the efficacy of international protocols and treaties.

This research identifies the major source region for new CFC-11 emissions as eastern mainland China, likely due to the new production of insulating foams used in buildings, which is not permitted under the Montreal Protocol.
 
Increased emissions of CFC-11 are of concern because it is a powerful ozone-depleting chemical. If emissions do not decline, it will delay the recovery of the Antarctic ozone hole, possibly for decades.