Updated radiative efficiencies and emissions metrics of halocarbons

Accurately quantifying the radiative properties of halogenated compounds is essential for climate change research, given their potent warming potential. While radiative transfer models facilitate explicit calculation of radiative efficiencies for individual gases, notable discrepancies persist among different studies. In this study, we apply an improved radiative transfer model to calculate the radiative efficiencies with stratospheric temperature adjustment for 15 key halogenated compounds, thereby revising marked overestimates identified in earlier applications of the original model. The results show that chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) contribute 64%, 16%, and 13%, respectively, to the 2023 radiative forcing (0.352 W/m²) from the 15 species. The radiative forcing of chlorinated compounds is in steady decline due to emission restrictions, whereas that of HFCs is highly scenario-dependent but projected to be 1.3 times the present level by 2100 under a policy-inclusive scenario. Furthermore, we assess the distinct impacts of long-lived and short-lived greenhouse gas emissions on global surface temperature using various emissions metrics. Temperature response simulations demonstrate that the conventional global warming potential (GWP-100) underestimates the initial warming from short-lived gas emissions by at least 50% while overestimating the post-mitigation warming by nearly a factor of four. Comparatively, emerging metrics contribute to reducing ambiguity in future warming estimates, owing to their closer alignment with model simulations. This study provides an updated physical basis for evaluating the radiative properties of halogenated compounds and supports more comprehensive climate policy assessments.