The role of air transportation on CO2 emissions in BRICS countries: Novel findings from MMQR methodology

This article examines the impact of air passenger and freight transportation, economic growth, energy consumption, trade openness, and FDI on the CO2 emissions in BRICS countries for the 1993–2021 period, utilising panel Fully Modified Ordinary Least Square (FMOLS) and Dynamic Ordinary Least Square (DOLS) estimators and Method of Moments Quantile Regression (MMQR) methodologies. According to the findings, air passenger transportation, economic growth, energy consumption and FDI have a positive impact on CO2 emissions, while squared economic growth and trade openness have a negative impact. Findings indicate that air freight transportation has no statistically significant effect on CO2 emissions. According to the causality analysis, there is a bidirectional causality between air passenger-CO2 emissions and GDP-CO2 emissions. There is a unidirectional causality from air freight to CO2 emissions, from energy consumption to CO2 emissions and from CO2 emissions to trade openness. © 2026 World Conference on Transport Research Society.