• Energy Research

This paper studies the effects of income inequality and financial instability on CO2 emissions in the presence of fossil fuel energy, economic development, industrialization, and trade openness. Moreover, the present study is the first to examine the moderating role of financial instability between income inequality and CO2 emissions. We utilized panel data of forty-seven developing countries for the period 1980–2016 by utilizing the stochastic impacts by regression on population, affluence, and technology (STIRPAT) model. The empirical outcomes in all models indicate that income inequality and industrialization significantly reduce environmental degradation, while fossil fuel, trade openness, and economic growth decrease the quality of the environment. However, financial instability (without interaction term) shows no significant link to environmental quality, whereas (with interaction term) it shows a significant negative effect on CO2 emissions. In addition, the result of the interaction variable reveals that an increase in inequality, ceteris paribus, in combination with the rise in financial instability, is expected to increase pollution. Furthermore, there exists a bidirectional causal association among income inequality, financial instability, fossil fuel, trade openness, industrialization, economic growth, and the interaction variable with CO2 emissions.

This study determines the dynamic linkages between road transport intensity, road transport passenger and road transport freight, and road carbon emissions in G20 countries in the presence of economic growth, urbanization, crude oil price, and trade openness for the period of 1990 to 2016, under the multivariate framework. This study employs the residual-based Kao and Westerlund cointegration technique to find long-run cointegration, and continuously updated bias-corrected (CUP-BC) and continuously updated fully modified (CUP-FM) methods to check the long-run elasticities between the variables. The long-run estimators' findings suggest a positive and significant impact of road transport intensity, road passenger transport, road freight transport on road transport CO2 emissions. Economic growth and urbanization are significant contributing factors in road transport CO2 emissions, while trade openness and crude oil price significantly reduce road transport CO2 emissions. The Dumitrescu and Hurlin causality test results disclose unidirectional causality from road transport intensity and road transport freight to the road transport CO2 emissions. However, the causality between road passenger transport and road transport CO2 emissions is bidirectional. Finally, comprehensive policy options like subsidizing environmental-friendly technologies, developing green transport infrastructure, and enacting decarbonizing regulations are suggested to address the G20 countries' environmental challenges.

The issue of urbanization has gained much importance over the last few decades due to its significant influence on economic growth and environmental quality, especially in developing countries. The non-linearity puzzle has been a long-debated issue, and prior studies provide mixed evidence. This study addresses the issue of urbanization using the measure of urban agglomeration and investigates the non-linear relation between urbanization and CO2 emissions at the regional level. The South Asian region represents approximately one-fourth of the world population and its urbanization needs to be addressed properly. This paper uses the annual data over the period of 1974–2014 for four South Asian countries, namely, Pakistan, India, Bangladesh, and Nepal. The panel cointegration tests establish the long-run relation between urbanization, urban agglomeration, economic growth, trade openness, energy consumption, financial development, and CO2 emissions. The fully modified ordinary least squares (FMOLS) model further confirms the existence of Environmental Kuznets Curve (EKC) in South Asia. Moreover, urbanization has an inverted U-shaped relation with CO2 emissions, while urban agglomeration has a U-shaped nexus with CO2 emissions for overall sample. The bidirectional causal relationship has also been confirmed between urbanization and CO2 emissions, between urban agglomeration and CO2 emissions, between financial development and CO2 emissions both in the long-run and short-run. On the other hand, unidirectional causality runs from economic growth, trade openness, and energy consumption to CO2 emissions in the long-run. The rising trend of urban agglomeration in metropolitan cities in South Asia is adversely affecting the environment. The current study has implications for policymakers and respective governments to adhere to more stringent urban planning.

This paper examines the environmental Kuznets curve (EKC) theory, augmenting the role of oil resources and energy consumption in carbon dioxide (CO2) emissions using the annual data of 11 African oil-producing countries from 1980 to 2014. We apply advanced panel cointegration and panel autoregressive distributive lag (ARDL) techniques coupled with Granger non-causality analysis to account for cross-sectional dependence and heterogeneity. The results of the augmented mean group (AMG) reveal that oil resources abundance degrades the environmental quality in Angola while abating CO2 emissions in Algeria, Gabon, Morocco, and Nigeria. Contrarily, energy consumption escalates pollution in the Congo Democratic Republic (COD), Côte d’Ivoire (CIV), Gabon, Morocco, and Tunisia. Our findings support the EKC hypothesis only in Cameroon, CIV, and Nigeria while exhibiting a U-shaped curve in Algeria and Morocco. Causality analysis unveils that oil resources Granger cause energy consumption, suggesting the balance between renewable and non-renewable energy sources. The current study has important policy implications for promoting green technology, economic diversification, service sector, and green investments.

Our pioneer study is aimed at investigating the role of the service sector in affecting sustainable environment in Pakistan. Using time series data over 1971–2014 and applying an autoregressive distributive lag (ARDL) model with structural break analysis, we establish a long-term equilibrium relationship of carbon dioxide (CO2) emissions with energy consumption, income level, services and trade openness. Our findings support a service-induced environmental Kuznets curve (EKC) hypothesis in Pakistan. The income level sharply raises environmental degradation at the early stage; however, after reaching a certain threshold, it improves environmental quality but at a lower rate. There exists an inverted U-shaped nexus between services and CO2 emissions, which implies that the service sector is less energy-intensive in terms of mitigating pollution in Pakistan. Moreover, the energy consumption has an inverted U-shaped effect on carbon emissions, which implies energy efficiencies and adoption of renewable energy has reduced pollution in the long run. The trade openness increases CO2 emissions in both the short term and long term. The quadratic term of income level has a negatively inelastic impact on CO2 emissions, which implies a very slow rate of improvement in environmental quality. On the other hand, the quadratic term of services shows a highly elastic impact on pollution, which induces the EKC hypothesis. Our robustness checks such as fully modified ordinary least squares (FMOLS), dynamic ordinary least squares (OLS), and Toda and Yamamoto (TY) causality tests further confirm the existence of the service-induced EKC hypothesis in Pakistan. Moreover, there exists a unidirectional causality from energy consumption to CO2 emissions, a bidirectional causal relationship between economic growth and CO2 emissions, and a unidirectional causal linkage between services and CO2 emissions. Lastly, we discuss certain policy implications for designing appropriate environmental and energy policies to mitigate the pollution in Pakistan.

This study investigates the heterogeneous impact of air transport intensity, air passenger transport, and air freight transport on air transport carbon emissions in G20 countries for the period of 1990-2016. The paper employs a robust and advanced fixed-effect panel quantile regression model that considers unobserved discrete and distributional heterogeneity. Our empirical results show that the impact of the independent variables on air transport carbon emissions is quite heterogeneous across various quantiles. More specifically, the effect of air transport intensity, air passenger transport, and air freight transport on carbon emissions is positive and becomes more assertive with the increasing trend at upper quantiles and is quite heterogeneous across all quantiles. Economic growth, urbanization, and tourism are significant contributing factors in enhancing air transport CO2 emissions, while crude oil price significantly reduces CO2 emissions. The Dumitrescu and Hurlin causality test estimates indicate that a bidirectional relationship extends from air transport intensity, air passenger transport, and air freight transport to air transport CO2 emissions. The findings underline the need for cleaner, renewable, and environmentally sustainable energy sources for air transport operations.

The rapid urbanization growth has not only improved the living standards of people but also raised concerns for environmental sustainability over the globe. In this regard, the issue of excessive urban concentration or over-agglomeration in metropolitan areas is nowadays the prime concern for urban planning and building energy-efficient and eco-friendly infrastructures. In response to rising interest in the dynamic linkage between urban concentration and environment, the current research empirically examines the crucial nexus between urban agglomerations and environmental degradation in top ten urban agglomerated countries in the world from 1960Q1 to 2014Q4. The current research is the pioneer empirical work in the area of urbanization by applying recently developed and innovative methods of quantile-on-quantile (QQ) approach and quantile Granger causality in relatively less explored area of urban agglomeration at the cross-country level. Our mainstream findings indicate that urban agglomeration has a strong positive effect on CO2 emissions in most of our sample countries, and this effect is more pronounced in higher quantiles of respective variables. These results imply that excessive levels of urban concentration in big cities cause environmental degradation, which could be attributed to extreme population density, overcrowding, traffic congestion and extensive demand for energy consumption. However, some countries such as Israel, Paraguay and Columbia exhibit overall declining and negative trends about the relationship between urban agglomerations and CO2 emissions. Moreover, quantile Granger causality results confirm the previous findings of QQ regression and verify the existence of bidirectional causal nexus between urban agglomerations and CO2 emissions in the majority of the lower, middle and upper quantiles in our selected top ten countries except for Kuwait. However, the unidirectional causal relationship also exists for several countries for extreme lower, middle and extremely higher quantiles. Our findings extend the previous work on agglomeration-environment nexus by determining the asymmetric magnitude of linkage between these two variables demanding cautious and individual-focused policies for urban planning and environmental sustainability.