In light of the growing importance of sustainable finance and renewable energy markets, this study examines how fluctuations in Germany's renewable energy sector interact with sustainability-related uncertainty. Using the wavelet quantile-on-quantile regression approach (WQQR), it investigates the influence of renewable energy sector prices, including solar energy, wind energy, and renewable fuels, on the ESG-Related Uncertainty Index (ESGUI-G) in Germany over the period from June 2008 to 2025. In the short term, we found a negative effect of S92G, ECVG, VBKG, and NDXG on ESGUI-G, and no effect was observed by CE2G and PNE. In the medium term, ESGUI-G was positively affected by CE2G, ECVG, PNE, and VBKG, and negatively affected by NDXG and S92G. In the long term, the results indicate that ESGUI-G is positively (negatively) affected by CE2G (NDXG, S92G, and VBKG). Furthermore, we observed a mix of positive and negative effects of ECVG and PNE on ESGUI-G in different quantiles. The results indicate that wind power equity is highly correlated with sustainability uncertainty, amplifying risk under both normal and turbulent market conditions. In contrast, green fuels and bioenergy firms exhibit short-term stability at low quantiles, followed by consistently positive effects in the medium and long term at higher quantiles, suggesting their potential as effective hedging tools under normal conditions, though they may exacerbate uncertainty in extreme circumstances.

Environmental degradation has intensified alongside rising carbon emissions driven by economic expansion, energy consumption, and transport activities. In recent decades, Middle Eastern economies have experienced substantial growth in tourism, trade openness, and energy use, raising concerns about their environmental consequences. This study investigates the impact of tourism activity, energy consumption, and trade openness on transport-related CO₂ emissions in ten Middle Eastern countries over the period 2000–2020. Data were obtained from the World Development Indicators (WDI) database of the World Bank. Using a panel autoregressive distributed lag (ARDL) framework, the analysis captures both short-run dynamics and long-run equilibrium relationships. To improve measurement robustness, tourism activity is proxied using two alternative indicators: international tourism expenditures (TEs) and international tourism receipts (TRs). The empirical results indicate that tourism activity and energy consumption significantly increase transport-related CO₂ emissions in both the short and long run, while trade openness does not exert a statistically significant long-run effect. These findings suggest that tourism expansion and energy-intensive transport systems are key contributors to environmental pressure In the region, whereas the environmental impact of trade may be indirect or conditional. The study highlights the importance of integrating sustainable tourism policies and improving energy efficiency. In addition, it underscores the need to develop low-carbon transport strategies to support environmentally sustainable economic development in Middle Eastern economies.

This study provides strong evidence of structural asymmetries between religious and non-religious tourism demand in Saudi Arabia over the period 2015Q1–2024Q4. The unit root results indicate that all variables are integrated of order one, supporting the application of the ARDL framework. The bounds test confirms the existence of a long-run equilibrium relationship for both religious and non-religious tourism. However, the strength and determinants of these relationships differ across tourism segments, providing evidence of structural heterogeneity in tourism demand. The empirical findings show that global oil prices do not have a statistically significant direct effect on either tourism segment in both the short run and the long run, suggesting that their influence is indirect and transmitted through broader macroeconomic channels. In contrast, non-oil GDP exerts a positive effect on non-religious tourism and remains weakly significant in the long run, highlighting the critical role of economic diversification and sustained income growth under Vision 2030. Religious tourism, however, remains largely unaffected by economic growth, reflecting its institutional and policy-driven nature. The COVID-19 pandemic had a severe and persistent negative impact on tourism demand, with a more immediate and pronounced effect on religious tourism due to the suspension of Hajj and Umrah activities. Adjustment dynamics indicate that both tourism segments converge toward their long-run equilibrium following short-run shocks, although religious tourism exhibits a somewhat faster speed of adjustment. Diagnostic tests confirm that all econometric assumptions are satisfied, supporting the robustness and reliability of the results.

The global energy transition requires countries to rapidly expand renewable energy infrastructure, yet the factors associated with this transition remain comparatively underexplored in resource-dependent economies. The Gulf Cooperation Council (GCC) represents a particularly important case: despite their substantial role in global hydrocarbon markets, they are simultaneously pursuing renewable energy expansion and economic diversification. Examining this transition therefore offers insights not only for the GCC but also for other hydrocarbon-dependent economies facing similar diversification challenges. This study examines, for the first time, the association between tourism development and renewable energy capacity share across six GCC countries from 2014 to 2024. Unlike most existing studies that use renewable energy consumption as the dependent variable, this study focuses on renewable energy capacity share, which more directly reflects long-term infrastructure investment and commitment to the energy transition. Using a balanced panel of 66 observations, the empirical analysis tests for cross-sectional dependence, applies the second-generation cross-sectionally augmented IPS (CIPS) unit root test, and estimates alternative panel specifications, with the fixed-effects model selected as the preferred specification based on the Hausman test. The results show that tourism receipts and foreign direct investment are positively and significantly associated with renewable energy capacity share, while GDP per capita shows no robust significant association. These findings highlight the potential relevance of tourism development and foreign investment to renewable energy expansion in hydrocarbon-dependent economies and provide policy-relevant evidence for countries seeking to align economic diversification with the energy transition.