Banned ozone-destroying chemical makes a mysterious resurgence

Banned Ozone-Harming Gas Creeps Back, Suggesting a Mystery Source

Mysterious rise in CFC11 emissions

Measurements from a dozen monitors around the world suggest the emissions are coming from somewhere around China, Mongolia and the Koreas, according to the study. He calls it "rogue production", adding that if it continues, "the recovery of the ozone layer would be threatened".

More than 30 years ago, world governments dealt with an alarming hole in the ozone layer with the Montreal Protocol, which banned damaging chemicals including the chlorofluorocarbon CFC-11.

The US National Oceanic and Atmospheric Administration (NOAA) in Colorado has alarmed the global community with their discovery of increased emissions of an ozone-depleting chemical, whose production was banned worldwide almost ten years ago.

However, a new study published this week in the journal Nature revealed that contrary to what is expected upon the banning of CFC-11 production, the harmful emissions are on the rise again, as the rate of CFC-11 decline in the atmosphere has been cut by 50 percent since 2012. But the researchers noticed the rate at which it is declining appeared to be slowing down. The CFC-11 chemical dropped steadily in the atmosphere by near about 2.1 parts-per-trillion per year in between the year 2002 and the year 2012.

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The researchers built mathematical models to account for these observations, which suggest CFC-11 emissions have actually been increasing by around 25% each year since 2012, despite virtually no CFC-11 production being reported to the relevant authorities during this time. CFC-11 was once commonly used in insulating foams, but it's now banned under the Montreal Protocol and reported production is close to zero. I think this will be quite a shock to many people who, like me, thought the Montreal Protocol was working well'. It is only destroyed in the stratosphere, some 9 to 18 miles above the planet's surface, where the resulting chlorine molecules engage in a string of ozone-destroying chemical reactions.

"The newer substances that are out there, the replacements for CFC-11, might be more hard or expensive for some countries to produce or get at". They also estimate that around 6,500 to 13,000 tons of new CFC emissions would fit the observed trend in atmospheric concentrations.

To be clear, CFC-11 concentrations in the atmosphere are still declining, but they're declining significantly more slowly because of the possible new source as compared to if there was none. The chemical can be a byproduct in other chemical manufacturing, but it is supposed to be captured and recycled. As one of the most potentially risky and previously widespread CFCs, used in refrigerants, spray can propellant, styrofoam production, etc., this is a worrying substance to be making a resurgence. 'Three different instrument measurements systems are used by NOAA to measure CFC-11, and they all showed the same trends, ' he says. "Emissions from "banks" would have had to have doubled, which is considered very unlikely, ' says Heard".

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