ABSTRACT This study addresses the challenge of global warming through a comprehensive understanding of country‐specific emission levels of QUAD nations—India, Japan, Australia, and the United States. While many studies have explored the economic‐environmental nexus, none, to our knowledge, have examined the presence of a cointegrating relationship amongst the CO 2 emissions of QUAD and the Environmental Kuznets Curve hypothesis for Japan. Here, Johnsen cointegration test, Wald test, quadratic regression, and Vector Error Correction Mechanism (VECM) techniques were employed on annual data for the period 1990 to 2020 to examine the long and short‐horizon relationships between emissions, and to validate the EKC hypothesis for the QUAD. The findings of our study reveal that emissions of QUAD are interdependent, and the countries in closer geographic proximity tend to have a more pronounced impact on each other's emission levels. The given findings underscore the need for tailored strategies to manage CO 2 emissions, highlighting the significance of the policy implications of our study.
Mahajan et al. (Tue,) studied this question.