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The dynamic stochastic effects regressions on population, affluence, and technology model used in this study reveals the nonlinear effects of urbanization routes on CO2 emissions in China, India, Indonesia, the United States, and Brazil during 1970–2020, using dynamic seemingly unrelated regression, dynamic ordinary least square, and fully modified ordinary least square techniques. The empirical analysis shows that urbanization and the proportion of small cities contribute significantly to CO2 emissions, while the square of urbanization and the square of the proportion of small cities significantly reduce CO2 emissions, thus supporting the inverted U-shaped relationship for the selected countries. However, the effect of the proportion of large cities significantly reduces CO2 emissions, while the square of the proportion of large cities significantly promotes CO2 emissions, supporting a U-shaped relationship for specific countries. Gross domestic product, industrial development, and transport infrastructure contribute significantly to carbon emissions, while renewable energy generation significantly reduces carbon emissions. The country-level augmented mean group estimator in the analysis supports an inverted U-shaped relationship between urbanization and carbon emissions and a U-shaped relationship between the proportion of large cities and carbon emissions in all selected countries. There is also an inverted U-shaped relationship between the proportion of small cities and carbon emissions in China, India, Indonesia, and Brazil. The causality test results acknowledge bidirectional causality between urbanization and carbon dioxide emissions; between urbanization squared and carbon dioxide emissions; between the proportion of the largest cities and carbon dioxide emissions, and between renewable energy and carbon dioxide emissions. This study recommends renewable energy options, green urban infrastructure, and digital technologies to improve the environmental quality of urban areas. [ABSTRACT FROM AUTHOR]

Most countries, notably those that signed the Paris Climate Agreement, prioritize achieving the zero carbon or carbon neutrality aim. Unlike earlier studies, this one assesses the contribution of environmental policy, clean energy, green innovation, and renewable energy to the E7 economies' achievement of carbon neutrality goals from 1990 to 2019. Findings emanating from the study show that the EKC hypothesis is valid in E7 countries. Implying that emissions in the E7 countries increased with the kick-off of development but declined later due to possible potent environmental regulatory policies put in place. Similarly, across all models, renewable energy (REN), green innovations (GINNO), environmental tax (ETAX), and technological innovations (TECH) were found to exert a negative and significant impact on carbon emissions in the E7 countries both in the short and long run. On the other hand, economic expansion (GDP) positively impacts environmental deterioration. Furthermore, the country-specific result shows that, on average, Brazil, India, China, Russia, Mexico, and Indonesia have significant environmental policies aiding carbon abatement. Except for Brazil, Mexico, and Indonesia, the income growth in the rest of the countries does not follow the EKC proposition. Furthermore, the causality result revealed a unidirectional causal relationship between GDP, REN, and GINNO to CO2 emission. No causality was found between ETAX with CO2, while a bi-directional causality exists between technology and CO2 emissions. Based on the finding, policymakers in the E7 countries should move away from fossil fuels because future electricity output will not be sufficient to reduce emissions considerably. Environmental regulations, encouraging technological innovation, adopting green and sustainable technology, and clean energy sources, among other things, demand radical and broad changes. [ABSTRACT FROM AUTHOR]