CFC banks release larger emissions than expected

In a study published in March 2020 in Nature Communications ⁽¹⁾, researchers of the Massachusetts Institute of Technology (MIT) have quantified contributions of chlorofluorocarbon (CFC) banks to emissions and impacts on the ozone layer and climate.

 

Pursuant to the Montreal Protocol, all nations agreed to phase out production of CFC-11 and CFC-12 by 2010.

 

CFC banks correspond to old equipment such as refrigeration and air-conditioning systems, and insulation foams, that was manufactured before the global phase out of CFCs and that is still releasing the gases into the atmosphere. These CFCs have lifetimes of up to multiple decades, thus contributing to current and future CFC emissions.

 

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

 

However, by using a Bayesian probabilistic model for CFC-11, 12, and 113 banks and their emissions, the MIT researchers found that bank sizes of CFC-11 and CFC-12 are larger than recent international scientific assessments suggested.

 

They found the amount of CFC 11 and 12 stored up in banks is about 2.1 million metric tons. These banks slowly leak these CFCs at concentrations that, if left unchecked, would delay the recovery of the Antarctic ozone hole by 6 years and add the equivalent of 9 billion metric tons 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,” concludes Susan Solomon, one of the co-authors of the study ⁽²⁾.

 

Sources:

 

⁽¹⁾ https://www.nature.com/articles/s41467-020-15162-7

⁽²⁾ http://news.mit.edu/2020/emissions-ozone-cfc-chemicals-0317