Published: Thu, May 17, 2018
Science | By Joan Schultz

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

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

Aerosol used to widely incorporate these unsafe chemicals.

A new study from National Oceanic and Atmospheric Administration, aka NOAA, has revealed that the production of ozone-destroying chemicals banned under the 1987 Montreal Protocol is still on and rising.

David Doniger, director of the climate and clean energy program of the Natural Resources Defense Council, an environmental group in Washington, said the new emissions were "bad for the ozone layer and bad for climate change".

According to the new study, published in the Nature magazine, unreported production of the second most damaging gas CFC-11, marketed as Freon and responsible with other chemicals from the CFC family for a giant hole in the Earth's UV-shield over the Antarctic, is located somewhere in eastern Asia.

Scientists have been carefully gathering data from air monitoring stations around the world ever since to make sure everything is progressing as anticipated. And good thing they did.

"We don't know why they might be doing that and if it is being made for some specific objective, or inadvertently as a side product of some other chemical process", said Stephen Montzka of the NOAA, lead author of the study. This chemical - previously used as a solvent, a refrigerant, as a precursor in styrofoam production, and a propellant in spray cans - is now banned for production under the protocol. However, these secondary sources should gradually decline, then disappear completely.

Nearly no CFC-11 has been been produced since 2006 - or so we thought. Following the introduction of the Montreal Protocol, atmospheric levels fell steadily from 2002 to 2012. CFC concentration in the atmosphere has declined by 15 percent from its peak in 1993, but over the past few years, the rate of decline has slowed down.

Image credits Montzaka et al. So the team came to the conclusion that someone is newly producing the chemicals. The substance is also a greenhouse gas that contributes to global warming. The concentration of these gases has always been higher in the (more developed, more industrialized) Northern Hemisphere than in the Southern one. However, the CFC-11 showed a relatively less drop of about 1.0 part-per-trillion each year in between the year 2015 and the year 2017. The team's models showed that natural variability in atmospheric circulation (aka weather patterns) could only explain half of the observed increase - meaning that the only plausible explanation is an increase in emissions.

"The authors pinpoint a new source of CFC-11 to East Asia, breaking Montreal Protocol rules". It is the first time levels of one of the three most abundant, long-lived CFCs has increased for a sustained period since the late 1980s.

The emissions are a direct violation of the Montreal Protocol. Since 2006, countries have reported close to zero production of CFC11.

He adds that the results could have "huge implications" for ozone recovery.

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