Rapid increase in Chloroform (CHCl3) emissions in China

Large and effective reductions in emissions of long-lived ozone-depleting substance (ODS) have been achieved through the Montreal Protocol, evidenced by the declining atmospheric abundances of many ODS. An important remaining uncertainty concerns the role of short-lived substances, with lifetimes generally under six months. Chloroform (CHCl3), is an important source of stratospheric halogens, but not regulated under the Montreal Protocol. Recent studies show that the Asian summer monsoon could act as a smokestack to pumping emitted air pollutants in East Asia to the stratosphere. Thus, CHCl3 emitted from East Asia becomes very important. In this study, CHCl3 emissions during the period 2007-2015 for China and other East Asian countries were determined using in-situ atmospheric measurements at ground stations and inverse modeling based on backward model simulation. Results show that CHCl3 emissions from China were very stable during 2007-2011 while emissions increased rapidly after that by more than 2 times through 2015. This study reveals that increase in global CHCl3 emission after 2012 can be attributed to the rapid emission increase in China. There is a growing threat to the ozone layer due to rapid increase in CHCl3 emissions in China.