Rethinking time-lagged emissions and abatement potential of fluorocarbons in the post-Kigali Amendment era
Heping Liu, Huabo Duan, Ning Zhang, Yin Ma, Gang Liu, T. Reed Miller, Ruichang Mao, Ming Xu, Jinhui Li, Jiakuan Yang
Abstract
The Montreal Protocol has been successful in safeguarding the ozone layer and curbing climate change. However, accurately estimating and reducing the time-lagged emissions of ozone-depleting substances or their substitutes, such as produced but not-yet-emitted fluorocarbon banks, remains a significant challenge. Here, we use a dynamic material flow analysis model to characterize the global stocks and flows of two fluorocarbon categories, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), from 1986 to 2060. We assess emission pathways, time-lagged emission sizes, and potential abatement measures throughout different life cycle stages while focusing on the role of banked fluorocarbons in global and regional decarbonization efforts in the post-Kigali Amendment era. Although fluorocarbon releases are expected to decline, the cumulative global warming potential (GWP)-weighted emissions of HCFCs and HFCs are significant; these will be 6.4 (±1.2) and 14.8 (±2.5) gigatons CO2-equivalent, respectively, in 2022–2060 in our business-as-usual (BAU) scenario. Scenario analysis demonstrates that implementing currently available best environmental practices in developed economies can reduce cumulative GWP-weighted emissions by up to 45% compared with the BAU scenario. The cumulative global warming potential-weighted emissions of hydrochlorofluorocarbons and hydrofluorocarbons are significant, which will be 21.2 (±3.7) gigatons CO2-equivalent in 2022–2060 under a business-as-usual scenario.