Comparative evaluation of CO2 emissions from transportation in countries around the world

It is important to objectively assess whether the transportation CO2 emissions (TCE) in individual countries are at low levels from the perspective of fairness. Previous studies have focused on directly comparing TCE or TCE per capita (TCEPC) in different countries and in different years, which may generate biased results, because each country has its own demographics and development status. To address this, this study establishes an evaluation framework that considers the heterogeneities of population, affluence, and technology in different countries in different years to provide benchmarks for evaluating the rationality of TCEPC fairly. Results from 115 countries from 1990 to 2019 show that population factors impact TCEPC more significantly than affluence and technology factors. In addition, TCEPC normally progresses from a rational low stage, to a non-rational medium-to-high stage, and then to a rational high-to-medium stage. Currently, most developed countries are at the third stage, while most developing countries are at the second stage.