Potential CFC-11 Sources and Their Potential Impact on Future Emissions and Banks

In 2018, Montzka et al reported an unexpected and persistent global emission increase of 13,000 tonnes of CFC-11 from 2014 to 2016 compared with 2002 to 2012.

Potential causes of the unexpected emissions are examined by modeling emissions from production and uses of CFC-11, considering technical and economic factors, and the possible use of new CFC-11 production. Most potential causes of the unexpected emissions have been eliminated, with only a few technical causes remaining as the likely sources. The production of closed-cell polyurethane foams remains a plausible explanation for the increased emissions.

A refined evaluation of CFC-11 in foam and chiller banks is also elaborated, to better determine the potential magnitude and duration of CFC-11 emissions on global and regional levels compared to emissions derived from atmospheric observations.

Scenarios for the production of CFC-11 that could explain resulting unexpected emissions are discussed, including the raw materials necessary to produce CFC-11 in sufficient quantities to supply the likely uses. Finally, the consequences of potential new CFC-11 production are discussed, including the growth of foam and chiller banks and the resulting longer-term CFC-11 emissions.