Report on unexpected emissions of CFC-11

peer reviewedEXECUTIVE SUMMARY Global CFC-11 emissions were expected to decrease steadily after 2010 because of the full phaseout of production and consumption. Surprisingly, however, CFC-11 emissions began to increase in 2013 and were high from 2014 to 2018. After the publication of this emission increase in 2018, emissions were substantially lower in 2019. A large fraction of the emission increase was attributed to Eastern China based on regional emission estimates. These regional emissions also declined substantially from 2017 to 2019. The increase in global CFC-11 emissions was not a result of increased bank releases. The amounts of CFC-11 in banks and the release rates from the banks remain highly uncertain. The increases in emissions observed to date are small enough not to have a major impact on CFC-11 atmospheric abundances, so they will not have a major impact on the expected stratospheric ozone recovery. However, the increases in banks and how they might augment future emissions have large uncertainties