Assessing the nonlinear impact of population aging on energy footprint: From the perspective of labor productivity and high-quality economic development

Amidst the ongoing low-carbon transition, the phenomenon of population aging is receiving increasing attention. Nevertheless, the relationship between population aging and environmental quality has not been conclusively established, and existing studies have yet to delve into the mechanism of the effect of population aging on energy and environmental quality. This paper utilizes the panel data of 30 Chinese provinces and regions from 2000 to 2019 and constructs the benchmark model, the nonlinear mediating effect, and the nonlinear moderating effect models to explore the nonlinear association between population aging and energy footprint, respectively. Additionally, we develop a comprehensive aging index employing principal component analysis (PCA) and measure the energy footprint by carbon sink approach. The results show that population aging has a nonlinear effect on the energy footprint with an inverted "U" shape and there is an inflection point on the curve of value 0.453. We also verify that population aging indirectly affects the energy footprint through its nonlinear impact on labor productivity, with an instantaneous mediating effect of 3.0902. Furthermore, the high-quality economic development has a nonlinear moderating impact on the inverted "U"-shape between population aging and energy footprint. As the level of high-quality economic development increases, the shape of the inverted "U" curve flattens out, and the inflection point shifts to the left. Among the five sub-indicators of high-quality economic development, green development has the most significant effect on the inverted "U" curve of population aging and energy footprint. These noteworthy findings offer valuable insights for formulating effective strategies to enhance the favorable effects of aging on environmental quality from multifaceted perspectives.