Chlorinated VSLSs Surpass HCFCs in CFC-11-Equivalent Emissions for Ozone Layer Depletion in China

Escalating emissions of chlorinated very short-lived substances (Cl-VSLSs), which remain unregulated under the Montreal Protocol, could delay the recovery of the global ozone layer. In this study, we developed a comprehensive sectoral and regional bottom-up emission inventory of the two most abundant Cl-VSLSs, dichloromethane (CH₂Cl₂) and chloroform (CHCl₃), from 2010 to 2023 in China, alongside projections to 2035. Our best estimates indicate an upward trend in historical emissions for both substances, with CH₂Cl₂ emissions more than doubling since 2010, and both species are projected to grow substantially by 2035 under the Business-As-Usual (BAU) scenario. The implementation of best practicable technologies is projected to mitigate cumulative CH₂Cl₂ and CHCl₃ emissions by approximately 50% and 7%, respectively, over 2024-2035. Crucially, projections indicate that the CFC-11 equivalent emissions of CH₂Cl₂ in China would exceed the country's aggregate emissions of all hydrochlorofluorocarbons (HCFCs) annually from 2024 onwards under the BAU scenario. This study underscores the need for integrated domestic regulations and international negotiations to address the increasing threat from Cl-VSLSs to stratospheric ozone recovery.