Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions

Emissions
of chloroform (CHCl3), a short-lived
halogenated
substance not currently controlled under the Montreal Protocol on
Substances that Deplete the Ozone Layer, are offsetting some of the
achievements of the Montreal Protocol. In this study, emissions of
CHCl3 from China were derived by atmospheric measurement-based
“top-down” inverse modeling and a sector-based “bottom-up”
inventory method. Top-down CHCl3 emissions grew from 78
(72–83) Gg yr–1 in 2011 to a maximum of 193
(178–204) Gg yr–1 in 2017, followed by a
decrease to 147 (138–154) Gg yr–1 in 2018,
after which emissions remained relatively constant through 2020. The
changes in emissions from China could explain all of the global changes
during the study period. The CHCl3 emissions in China were
dominated by anthropogenic sources, such as byproduct emissions during
disinfection and leakage from chloromethane industries. Had emissions
continued to grow at the rate observed up to 2017, a delay of several
years in Antarctic ozone layer recovery could have occurred. However,
this delay will be largely avoided if global CHCl3 emissions
remain relatively constant in the future, as they have between 2018
and 2020.