"It is therefore imperative that this finding be discussed at the next Ministerial meeting of Governments given recovery of the ozone layer is dependent on all countries complying with the Montreal Protocol (and its adjustments and amendments) with emissions globally dropping to zero". This was partly because nations had all agreed to ban or phase out CFCs, which are short for "chlorofluorocarbons" but are simply called "ozone-depleting substances", due to an global treaty back in the 1980s called the Montreal Protocol.
"Emissions today are about the same as it was almost 20 years ago", he said.
Another key question is whether there could be another explanation for a slower decline in CFC-11 post-2012, such as a change in the rate of chemical processes such as UV photolysis that break down CFC-11 in the stratosphere, or an increase in emissions from CFC "banks" - reservoirs that persist in old equipment and products that are still in use.
Nearly no CFC-11 has been been produced since 2006 - or so we thought. "We don't know why they might be doing that and if it is being made for some specific goal, or inadvertently as a side product of some other chemical process", said Stephen Montzka of the NOAA, lead author of the study.
If the source of these new emissions can be identified and controlled soon, the damage to the ozone layer should be minor, Montzka said. And thanks to the agreement, we've avoided a total ozone layer collapse by mid-century.
Exploring further, the researchers found the concentration of CFC-11 to be unusually high in the Northern Hemisphere.
The information has led the researchers to hypothesise that the emissions are coming from the Northern Hemisphere.
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But "continued increase in global CFC-11 emissions will put that progress at risk".
So where exactly are these increased emissions coming from?
"We are making the measurements from very far away from these regions and I think more specificity is going to come once the people.in that region.look carefully at their measurements and publish their results", he added.
The researchers have calculated that an additional 6,500 to 13,000 tons emitted each year in Eastern Asia would be enough to account for the trend.
CFC-11, used primarily for foams, can lasts up to 50 years in the atmosphere once it's released.
If the study is verified, this would be a clear violation of the Montreal Protocol.
"These considerations suggest that the increased CFC-11 emissions arise from new production not reported to UNEP's Ozone Secretariat, which is inconsistent with the agreed phase-out of CFC production in the Montreal Protocol by 2010", the researchers wrote. "There's a reasonable chance we'll figure out what's happening here", he said. 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. If you want more like this, head over to Science As Fact.