Can multifarious types of green bonds be accused of greenwashing with a durative analysis? Insights from a permanent causality vs. temporary causality phenomenon

Green bonds are useful monetary tools that can finance sustainable endeavors to bolster an eco-friendly economy. This research inspects the frequency-domain causal relationship between diverse green bond types and the green economy from June 30, 2014 to August 3, 2023. The goal is to understand both permanent and temporary causal phenomena between them. The findings reveal that only pioneering green bonds display a robust bidirectional causal link with an eco-efficient economy. Meanwhile, other green bond types, like conventional, municipal, and currency-dominated green bonds, may be susceptible to greenwashing due to the absence of a thorough permanent causal tie with an ecologically sustainable economy. Additionally, enhancing pioneering green bonds by integrating ESG (Environmental, Social, and Governance) stocks can transform the cause-and-effect dynamic between specific green bonds and the green economy. It shifts from a bilateral cause to a unilateral one stemming from the environmentally friendly economy and extending to distinguished green bonds. This phenomenon persists whether the 5% annual fee for sustaining and managing the index combining green bonds and ESG equities is considered or not. Interestingly, an environmentally conscious economy, in both persistent and transient associations, consistently affects ecological bonds with diverse traits. This highlights the importance of the overall state of an environmentally responsible economy in enhancing green bonds. These discoveries provide novel perspectives for green market regulators and policymakers to design improved standards for green assets.