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

Dwayne Harmon
May 17, 2018

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 from ozone depletion, '" NOAA scientist Stephen Montzka, lead author of the paper, said in a statement. The discovery is likely to encourage the worldwide investigation of a mysterious source.

The standard reference for CFC concentrations, the United Nations Environment Program's Handbook for the Montreal Protocol, reported in its 2012 edition that production of CFC-11 was very close to zero.

The scientists said the deviation coincided with a rise in amounts of two other chemicals, chlorodifluoromethane and dichloromethane, suggesting they were all coming from the same source, though it was not clear exactly where they were being produced.

The researchers show that CFC-11 levels, measured at a number of remote monitoring sites around the world, decreased in line with expectations between 2002 and 2011.

If you thought the crisis over the gaping hole in the ozone layer was under control, prepare to be disappointed. A US observatory in Hawaii found CFC-11 mixed in with other gases that were characteristic of a source coming from somewhere in east Asia, but scientists could not narrow the source down any further.

There is a small chance that there is a more innocent explanation for the rise in CFC-11 emissions, the scientist say.

The protocol was a huge success, slowly shrinking the giant hole that forms over Antarctica each September.

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But they concluded these sources could not explain the increase, which they calculated at about 13 billion grams per year in recent years.

To put this in perspective, at peak emissions in the 1980s, the world was producing 350,000 tons of CFC-11 each year, before dropping to 54,000 tons per year at the turn of the century. 'The slower decline in CFC-11 means a delay in recovery, and as CFC-11 is a strong greenhouse gas this [will also contribute] to more global warming'. 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.

Watson suggested that aircraft flights might be necessary to better identify the source of the emissions.

Plus, it isn't just CFC-11 that was found to be increasing.

But in the last few years, it looks like someone has started cheating.

The situation got even worse in the years after 2012 when the rate of CFC decline slowed by 50 percent, which could have only been possible due to an increase in CFC emissions.

"Knowing how much time and effort and resources have gone into healing the ozone layer, and to see this is a shocker, frankly", said Montzka.

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