Dynamic relationships between environment-related technologies, agricultural value added, transport infrastructure and environmental emissions in the five most populous countries

Densely populated countries have higher demand for agricultural products and greater use of fuel and vehicles, resulting in higher environmental emissions, so this study considers transportation infrastructure and the agricultural sector as the two major drivers of environmental degradation in the top five densely populated countries. In a baseline regression, this study first unveils the impact of investments in transportation infrastructure, agricultural value addition, and environment-related technologies on per capita CO₂ emissions using CS-ARDL approach from 1990 to 2021 in the five most populous countries. Besides, this study also reveals the typical moderating effect of environment-related technologies in the link between transport infrastructure, agricultural value added and environmental hazards. The results of the baseline model indicate that transport infrastructure and agricultural value added can substantially contribute to per capita carbon emissions in both the short and long term. However, environment-related technologies significantly reduce environmental emissions in both the short and long term. Per capita GDP extensively promotes per capita carbon dioxide emissions, while per capita GDP² substantially reduces per capita carbon dioxide emissions in the long term rather than the short term, thus authenticating the inverted U-shaped EKC hypothesis for the top five countries with the highest population density. The moderating effect of environment-related technologies shows that the application of environment-related technologies in both transportation and agriculture can alleviate environmental pollution. Finally, the threshold level of environment-related technologies shows that as environment-related technologies move from lower threshold levels (≤ - 1.05) to higher threshold levels (> -1.05), agricultural value added and transportation infrastructure investment significantly improve the reduction of environmental contamination. The goal of environmental sustainability can be ensured by the adoption of environment-related technologies in agriculture and transportation sectors.