Abstract
An important recent achievement in environmental macroeconomics is that reported by Cheng et al. [J. Macroecon. 81, 103614 (2024)]. Their model implements multiple growth engines and realizes the double dividend of economic growth and environmental improvements. However, regarding the environmental aspect, the situation could change drastically in general cases, and so a detailed understanding of the mechanisms in such cases is important for future similar studies. This paper presents additional numerical results that complement the analysis by Cheng et al. (2024), clarifies the underlying mechanisms, and makes some policy comments.