Last updated May 24, 2019 at 3:26 pm
Australian and British scientists have cracked the case of a strange increase in an ozone-depleting chemical that has been banned for decades.
Atmospheric CFC levels have been on the decline since the mid-1990s, when they were phased out as part of the Montreal Protocol Agreement.
Since then, most of the emissions have been due to CFCs leaking from ‘banks’ – buildings and products that were produced with CFCs before the ban.
But in 2013, this decline slowed and Aussie and international researchers detected a mysterious rise in emissions of CFC-11.
CFC-11 is a chemical that was used in ‘foam blowing’ – a process that was used to insulate buildings and other products like refrigerators.
Worldwide hunt for origin of CFC-11 emissions
To trace the origins of this rise, the researchers gathered emissions data from monitoring stations across the globe, including Australia, the US, Europe, Japan and South Korea, and found the emissions came from East Asia – around the Shandong and Hebei provinces in China.
Study author Dr Paul Fraser from the CSIRO Climate Science Centre told the AusSMC these emissions are “likely due to the new production of insulating foams used in buildings, which is not permitted under the Montreal Protocol.”
The emissions from these areas account for at least 40-60 per cent of the increase, according to the authors, and were ten times higher than CFCs released from all fridges disposed of in China between 2014-2017, and equal to emissions predicted for building demolitions for the entire world over 20 years.
This indicates the emissions are due to new, unrecorded production and use of CFCs, the paper authors said, and could not simply be due to CFCs leaking from ‘banks’.
Australian CFC emissions not contributing to global increase
Paul Krummel from the CSIRO Climate Science Centre, another author on the paper, told the AusSMC they were also able to rule out Australia as a possible cause using Tasmanian data.
“In Australia, CFC-11 levels are monitored at the Cape Grim Baseline Air Pollution Station in Tasmania,” he said.
“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.”
Professor Ian Rae from the School of Chemistry at the University of Melbourne told the AusSMC that CFC-11 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 in the ozone layer that stops dangerous ultraviolet radiation reaching Earth’s surface,” he said
Rogues try to use old chemicals
Professor Rae said the problem with CFCs is that they’re effective at what they do, so rogue users of old supplies occasionally try to get away with using these chemicals again.
“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,” he said.
“However, regulators like China’s EPA and some in other countries have found it difficult to deal with the rogues.”
These parties must be dealt with, however, as CFCs cause detrimental effects that are long term and far-reaching.
“Increased emissions of CFC-11 are of concern because it is a powerful ozone-depleting chemical,” Dr Fraser said.
“If emissions do not decline, it will delay the recovery of the Antarctic ozone hole, possibly for decades.”