Rethinking time-lagged emissions and abatement potential of fluorocarbons in the post-Kigali Amendment era

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.