This study investigates the energy security and income roles in testing environmental Kuznets curve (EKC) for developing countries from 1990 to 2019. The panel quantile regression approaches are employed to examine the relationship between the variables, considering that income and energy security effects on carbon emissions may vary across distributions. Findings revealed that the EKC hypothesis was inconsistent at low and high quantiles when estimating energy availability, affordability, and acceptability. The validity of inverted U-shaped EKC is supported at high quantiles for energy affordability and accessibility in developing countries. However, given the energy accessibility and acceptability, the EKC hypothesis becomes invalid in developing countries. Notably, developing countries have yet to progress toward achieving energy security as a switch component to low carbon emissions. This study contributes to the literature by revealing the effect of availability, accessibility, affordability, and acceptability of energy security on carbon dioxide emissions (CO2). Thus, it suggests implications for improving environmental quality in developing countries by enhancing energy security. Diversifying energy sources with nuclear, renewable, and developing technologies reduces dependence risks on a single source while improving efficiency through technology and demand management lowers carbon emissions and strengthens energy security. Beyond energy security, this study emphasises sustainable urban planning to promote compact development, effective transportation, and green infrastructure to reduce energy use and improve environmental sustainability, ultimately reducing carbon emissions.
This study examines the impact of government spending, income, and tourism consumption on CO2 emissions in the 50 US states through a novel theoretical model derived from the Armey Curve model and the Environmental Kuznets Curve hypothesis. The findings of this research are essential for policymakers to develop effective strategies for mitigating environmental pollution. Utilizing panel cointegration analysis, the study provides valuable insights into whether continued increases in government spending contribute to higher pollution levels. By identifying the threshold point of spending as a percentage of GDP, policymakers can make informed decisions to avoid the trade-off between increased spending and environmental degradation. For instance, the analysis reveals that Hawaii's tipping point is 16.40%. The empirical results underscore the importance of adopting sustainable policies that foster economic growth while minimizing environmental harm. These findings will aid policymakers in formulating targeted and efficient approaches to tackle climate change and promote long-term environmental sustainability in the United States. Moreover, the impact of tourism development on CO2 emissions varies across states, with some US states experiencing a decrease while others see an increase.