Mysterious rise in CFC11 emissions

Mindy Sparks
May 17, 2018

Paul Young, at Lancaster University, UK, said: "The Montreal Protocol has been rightly hailed as our most successful global environmental treaty, so the suggestion that there are possibly continued, unreported emissions of CFCs is certainly troubling and needs further investigation".

An ozone depleting CFC refrigerant, thought to be virtually extinct following Montreal Protocol phase outs, has mysteriously reappeared in increasing amounts in the atmosphere.

Countries have reported close to zero production of the chemical since 2006 but the study found about 14,300 tons (13,000 metric tons) a year has been released since 2013. The startling resurgence of the chemical, reported in Nature, will likely spark an worldwide investigation to track down the mysterious source.

Zaelke said he was surprised by the findings, not just because the chemical has always been banned but also because alternatives exist, making it hard to imagine what the market for CFC-11 today would be.

A chemical banned due to the harm it causes the ozone layer may be secretly in production somewhere in the world.

But starting in 2013, emissions of the second most common kind started rising, according to a study in Wednesday's journal Nature.

They considered a range of alternative explanations for the growth, such as a change in atmospheric patterns that gradually remove CFC gases in the stratosphere, an increase in the rate of demolition of buildings containing old residues of CFC-11, or accidental production.


"There's a reasonable chance we'll figure out what's happening here", he said.

CFC-11 still contributes about a quarter of all chlorine - the chemical that triggers the breakdown of ozone - reaching the stratosphere.

Nearly no CFC-11 has been been produced since 2006 - or so we thought.

"The ozone layer remains on track to recovery by mid-century", the UN Environment Programme (UNEP) said in a statement, reacting to the findings.

Two decades ago, CFCs - more potent by far as greenhouse gases than carbon dioxide or methane - accounted for around ten percent of human-induced global warming.

The Montreal Protocol, signed by more than 200 countries and generally regarded as having a good record of compliance, is created to protect the Earth's ozone layer. Use of the chemical was banned in 2010 via the Montreal Protocol, an worldwide agreement made to protect the environment. "It's therefore critical that we identify the precise causes of these emissions and take the necessary action". However, that decrease is significantly slower than it would be without the new CFC emissions. In 2012, however, the rate of decline suddenly reduced by about 50% - indicating that new source of production had started up.

"If the increased emissions were to go away [soon], it's influence on the recovery date for the ozone layer would be minor", he said.

Other reports by Iphone Fresh

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