Emissions of a banned, ozone-depleting chemical are on the rise, a group of scientists reported Wednesday, suggesting someone may be secretly manufacturing the pollutant in violation of an global accord. "Further work is needed to figure out exactly why emissions of CFC-11 are increasing and if something can be done about it soon".
"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".
Thirty years or more ago CFC11 (R11) was commonly used as a refrigerant and insulation propellant.
Officially, the production of CFC-11 should be near zero or nearly zero - at least, those are the countries that cooperate with the United Nations body that monitors and ensures compliance with the Montreal Protocol. This means that the total concentration of ozone-depleting chemicals, overall, is still decreasing in the atmosphere.
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. Rather, the evidence "strongly suggests" a new source of emissions, the scientists wrote. Then, surprisingly, the rate of decline hardly changed over the decade that followed. In 2012, however, the rate of decline suddenly reduced by about 50% - indicating that new source of production had started up. After considering a number of possible causes, Montzka and his colleagues concluded that CFC emissions must have increased after 2012.
The slowdown in reduction of CFC-11 also has implications for the fight against climate change.
Unreported production of CFC-11 outside certain specific carve-out purposes in the treaty would be a "violation of global 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. Scientists say there's more of it - not less - going into the atmosphere and they don't know where it is coming from.
However, results from the new analysis of NOAA atmospheric measurements show that from 2014 to 2016, emissions of CFC-11 increased by more than 14,000 tons per year to about 65,000 tons per year, or 25 percent above average emissions during 2002 to 2012.
"You are left with, boy, it really looks like somebody is making it new", said Montzka, who noted that the less damaging replacement for CFC-11 is more expensive to make.
As a result of the controls, CFC11 concentrations have declined by 15% from peak levels measured in 1993.
But there a growing scientific doubts about the progress of healing in the ozone hole.
Erik Solheim, head of UN Environment, said: "If these emissions continue unabated, they have the potential to slow down the recovery of the ozone layer".
These findings represent the first time emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since production controls took effect in the late 1980s.
A study earlier this year found that the ozone layer is unexpectedly declining in the lower stratosphere - 10 to 24 kilometres above sea level - over the planet's populated tropical and mid-latitude regions.
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.