Mysterious rise in emissions of ozone-damaging chemical
- Author: Regina Walsh May 17, 2018,
May 17, 2018, 16:02
CFC-11 was originally used as a refrigerant but was banned in 1987 under the Montreal Protocol, the global agreement created to protect the ozone layer. Movement of gases around the atmosphere, the destruction of buildings harboring CFCs from the 1970s and the failure to capture the chemical during the production of other chemicals could all lead to a rise in CFC-11, but not almost enough to explain the results.
Though they do not know who's responsible for the mysterious spike in CFC levels, the wide-spanning NOAA measurements, such as the difference between CFC-11 concentrations on both hemispheres, have hinted that the source might be located somewhere on the northern hemisphere, possibly around Eastern Asia.
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 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'.
Rogue production, the scientists wrote, seemed to be the best explanation. "In the end, we concluded that it's most likely that someone may be producing the CFC11 that's escaping to the atmosphere", he said. 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.
To put that in perspective, production of CFC-11, marketed under the trade name Freon, peaked at about 430,000 tons per year in the 1980s.
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.
Watson suggested that aircraft flights might be necessary to better identify the source of the emissions.
Unreported production of CFC-11 outside of certain specific carve-out purposes in the treaty would be a "violation of worldwide law", Weller confirmed, though he said that the Protocol is "non-punitive" and the remedy would probably involve a negotiation with the offending party, or country. "They should tell the industries that's not going to work".
Overall, it is important to underscore that the ozone layer is slowly recovering and ozone-depleting substances are still declining. "Nevertheless, scientists and policy makes will want to understand the cause of these unexpected CFC-11 emissions". If not, our ozone layer's fragile recovery could be under threat.
"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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