International environment agreements and emissions reduction: new insights from a staggered difference-in-difference analysis

Abstract The Kyoto Protocol and the subsequent Doha Amendment represent crucial milestones in international environmental efforts to establish binding emission reduction targets for the participating members. Many studies have examined the effects of the former, but not many the latter, on emissions reduction; however, their impact is inconclusive. One major reason may be due to the heterogeneous issue arising from the fact that countries ratified and implemented those agreements at different times. This study is the first to employ the staggered difference-in-difference method to analyse the two agreements within a unified framework. We empirically found that ratifying the Kyoto Protocol has significantly contributed to a decrease in global carbon dioxide emissions, although the impacts of the Doha Amendment are not statistically clear, underscoring the substantial role those agreements can play in protecting the global environment. Our findings are robust across several techniques, including the imputation estimator and the average group-time treatment approach.