Achieving environmental sustainability has become a global initiative whilst addressing climate change and its effects. Thus, this research re-assessed the EKC hypothesis in China and considered the effect of hydroelectricity use and urbanization, utilizing data from 1985 to 2019. The autoregressive distributed lag (ARDL) bounds testing method was utilized to assess long-run cointegration, which is reinforced by a structural break. The outcome of the ARDL bounds test confirmed cointegration among the series. Furthermore, the ARDL revealed that both economic growth and urbanization trigger environmental degradation while hydroelectricity improves the quality of the environment. The outcome of the ARDL also validated the EKC hypothesis for China. In addition, the study employed the novel gradual shift causality test to capture causal linkage among the series. The advantage of the gradual shift causality test is that it can capture gradual or smooth shifts and does not necessitate previous information of the number, form of structural break(s), or dates. The outcomes of the causality test revealed causal connections among the series of interest.

The aftermath of the COVID-19 pandemic has two striking impacts on the economy of the Kingdom of Saudi Arabia. First, the economic contraction of business and economic activities. Second, the effect of oil prices dropping as energy demand decreases in the international market. This study seeks to underpin the linkage between GDP growth, oil price, foreign direct investment (FDI), air transport, social globalization and carbon dioxide emission by applying time-series econometrics techniques of the following: fully modified ordinary least squares, dynamic ordinary least squares and canonical tests. The results of the Johansen cointegration test and empirical analysis trace a long-run equilibrium relationship between the highlighted variables. Our study shows that a 1% increase in FDI attraction increases economic growth by 0.004%; similarly, air transport and oil rent from KSA increased economic growth by 0.547% and 0.005%, respectively. These outcomes are indicative of the GDP growth ambition of the KSA economy in order to intensify FDI attraction and the air transportation sector. However, we also observe that increases in CO2 emission increase GDP growth. Thus, this suggests that the economic growth in KSA is not green, indicating the need for green economic growth pursuit targets.

In accordance with the Intergovernmental Panel on Climate Change (IPCC), Kyoto protocol and the United Nations Sustainable development goals (UNSDGs) on climate action (SDG-13), there has been a need across economies for transition from fossil-fuel-based energy sources such as coal energy consumption to cleaner energy options i.e., a transition to a low-carbon economy. To this end, the present study explores the asymmetric relationship between coal energy consumption, economic growth, rising urban population and emission level in South Africa. The present study span is conducted on an annual frequency basis from 1965-2018. This study applies the novel Non-linear Autoregressive distributed lag methodology (NARDL) for the highlighted variables. Empirical results validate the asymmetric relationship between the variables under review over the study period. The NARDL regression further shows positive shock by GDP increases CO2 emission level while negative impact affects otherwise in the long run. On the other hand, coal consumption positive shock exhibits a detrimental impact on environmental quality in South Africa. This is insightful for policymakers. The urban population shows non-significant effect on emission levels over the sampled period. The knowledge of both positive and negative shock effects of GDP, coal energy consumption and urban growth is vital for policy construction in terms of both economic and environmental sustainability. Thus, policy prescription ranges from energy transition to alternative and cleaner energy sources like renewables and responsible energy consumption (SDG-12) should be pursued in South Africa. More far-reaching environmental policies are highlighted in the concluding section.