In recent months stories have emerged of an increase in CFC-11 emissions which is in direct violation of the Montreal Protocol.

While the ozone layer is on a recovery path, Massachusetts Institute of Technology (MIT) scientists have found unexpectedly high emissions of CFC-11 and CFC-12, raising the possibility of production of the banned chemicals that could be in violation of the landmark global treaty.

Emissions of CFC-11 even showed an uptick around 2013, which has been traced mainly to a source in eastern China. New data suggest that China has now clamped down on illegal production of the chemical, but emissions of CFC-11 and 12 emission are still larger than expected.

Now MIT researchers have found that much of the current emission of these gases likely stems from large CFC “banks” — old equipment such as building insulation foam, refrigerators and cooling systems, and foam insulation, that was manufactured before the global phaseout of CFCs and is still leaking gases into the atmosphere.

Based on earlier analyses, scientists concluded that CFC banks would be too small to contribute very much to ozone depletion, and so policymakers allowed the banks to remain.

It turns out there are oversized banks of both CFC-11 and CFC-12, the scientists said in a MIT News article in mid-March this year.

The banks slowly leak these chemicals at concentrations that, if left unchecked, could delay the recovery of the ozone hole by six years and add the equivalent of 9 billion metric tonnes of carbon dioxide to the atmosphere — an amount that is similar to the current European Union pledge under the UN Paris Agreement to reduce climate change.

“Wherever these CFC banks reside, we should consider recovering and destroying them as responsibly as we can,” says Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT, who is a co-author of the study. 

The team also identified an unexpected and sizable source of another ozone-depleting chemical, CFC-113. This chemical was traditionally used as a cleaning solvent, and its production was banned, except for in one particular use, as a feedstock for the manufacturing of other chemical substances. It was thought that chemical plants would use the CFC-113 without allowing much leakage, and so the chemical’s use as a feedstock was allowed to continue.

However, the researchers found that CFC-113 is being emitted into the atmosphere, at a rate of 7 billion grams per year — nearly as large as the spike in CFC-11, which amounted to about 10 billion grams per year.


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