Published: Thu, May 17, 2018
Research | By Jody Lindsey

Banned ozone-destroying chemical makes a mysterious resurgence

Banned ozone-destroying chemical makes a mysterious resurgence

Staff at the South Pole get ready to release a balloon that will carry an ozone instrument up to 20 miles in the atmosphere, measuring ozone levels all along the.

The authors of the new report discount the idea that this change could be due to releases from existing stores, emissions from older buildings being decommissioned, or from the accidental production of CFC-11 as a by-product of other chemical manufacture.

A simple model analysis of our findings suggests an increase in CFC-11 emissions ... despite reported production being close to zero4 since 2006 ...

The rise in CFC-11 was revealed by Stephen Montzka, at the US National Oceanic and Atmospheric Administration (NOAA) in Colorado, and colleagues who monitor chemicals in the atmosphere. "Further work is needed to figure out exactly why emissions of CFC-11 are increasing and if something can be done about it soon". Global production of CFC-11, which has been used as a refrigerant and in insulating foams, has been banned since 2010 under the Montreal Protocol. Rather, the evidence "strongly suggests" a new source of emissions, the scientists wrote.

The researchers said that the less rapid decline of CFC-11 could prevent ozone from returning to normal levels, or at least as quickly as hoped.

The new study published on Wednesday shows that, as expected, the rate of decline of concentrations of CFC-11 observed was constant between 2002 and 2012.

The slowdown in reduction of CFC-11 also has implications for the fight against climate change.

Measurements from Hawaii indicate the sources of the increasing emissions are likely in eastern Asia. Scientists say there's more of it - not less - going into the atmosphere and they don't know where it is coming from.

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The Montreal Protocol has been effective in reducing ozone-depleting gases in the atmosphere because all countries in the world agreed to legally binding controls on the production of most human-produced gases known to destroy ozone.

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. CFC-11 concentrations have declined by 15 percent from peak levels measured in 1993 as a result.

That speculation is due to increased CFC-11 emissions, a big issue that could delay ozone restoration efforts and contribute to a warming planet. But the apparent increase in emissions of CFC-11 has slowed the rate of decrease by about 22 percent, the scientists found. "But this is most surprising one".

"If the emissions were to persist, then we could imagine that healing of the ozone layer, that recovery date, could be delayed by a decade", said Dr Montzka.

The ozone layer is slowly recovering, and ozone-depleting substances are still declining.

David Fahey, director of NOAA " s Chemical Science Division and co-chair of the United Nations Environment Programme's Ozone Secretariat 's Science Advisory Panel, said ongoing monitoring of the atmosphere will be key to ensuring that the goal of restoring the ozone layer is achieved.

But Mr. Doniger noted that the Montreal Protocol, which has been signed by almost 200 countries, has a strong track record of compliance, with countries often reporting their own violations.

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