The decomposition of total-factor CO₂ emission efficiency of 97 contracting countries in Paris Agreement

Greenhouse gas reduction requires joint efforts from the global society, while improving CO₂ emission efficiency is a centrally important means to realize emission reduction targets. Therefore, it is of strategic importance to identify main influential factors to CO₂ emission efficiency of different countries by considering the technology heterogeneity. The originality herein lies in that, applying the modified decomposition method of Metafrontier Malmquist Luenberger Index (MML) to define the priority of contracting countries in Paris Agreement to improve emission efficiency. In this study, 97 contracting countries of Paris Agreement are divided into 4 groups according to levels of income (low-income countries, lower-middle income countries, upper-middle income countries and high-income countries), and studied with their input and output data during 1990–2014 as samples. The empirical results reveal that the paths for the contracting countries of Paris Agreement to improve the efficiency are different: first, lower-middle income group can be facilitated through increasing factor input to increase the MML index considering the highest increase in scale efficiency (2.78%). Second, low-income group should eliminate the excessive concentration of inputs by enhancing the energy management efficiency. Third, in terms of the significant advancement of high-income group's MML index brought by technology advancement and the abnormal drop of Brunei Darussalam's MML related to technology decay, this analysis emphasized that the advancement and innovation of energy technology are the main force for total-factor CO₂ emission efficiency improvement.