The Effect of Energy Consumption, Income, and Population Growth on CO2 Emissions: Evidence from NARDL and Machine Learning Models

With population and income growth, the need for energy has increased in developing and emerging economies, which has inevitably led to an increase in carbon dioxide emissions (CO(2)e). This paper investigates the impact of energy consumption on CO(2)e influenced by population growth, energy consumption per capita, and income. In particular, this paper investigates whether or not an increase in energy consumption, energy intensity, energy consumption per capita, population growth, and income impacts CO(2)e in China, India, and the USA. The study applied the non-linear Autoregressive distributed lag (NARDL) and machine learning techniques. We found a significant impact of energy consumption per capita on the CO2 emissions in China, India, and USA. Furthermore, the results revealed that, when income increased, CO2 emissions increased in India, but decreased in the USA. The results confirmed that population growth increases CO2 emissions only in India. The results revealed that a decrease in energy intensity significantly improves the environmental quality in China and India. Finally, we forecasted the CO(2)e trend from 2017 to 2025. The results revealed an upcoming increase in CO(2)e levels in China and India. Conversely, the forecasted results demonstrated a downward trend of CO(2)e emissions in the USA.