The association between suitable compactness of urban expansion and urban green growth

Abstract

Explicit urban growth patterns (UGPs) exhibit complex association with implicit urban green growth (UGG). However, the scaling trajectories linking carbon metabolism and socio-economic development in UGG remain uncertain, and it is unclear which UGP is optimal for local or global UGG. Here, we establish dynamic scaling laws between CO₂ emissions and the socio-economic size of 77,677 newly built-up patches over 2012–2020 in China to accurately assess the performance, types, and progress of UGG and further elucidate its suitable UGP and associated factors across scales. Our analysis reveals that UGG performance shows a latitudinal gradient but is significantly poorer in large cities and central China. China’s newly built-up patches display distinct development types, with over three-quarters of them achieving UGG via sub-linear (27.8%) or negative (48.9%) carbon metabolism response patterns to socio-economic growth, whereas the remainder face super-linear carbon pressure (19.5%) or socio-economic decline (3.8%). Notably, compact infill expansion emerges as a locally greener UGP across diverse spatial scenarios, reducing the carbon cost of socio-economic development by 24% and 45% compared to edge and outlying expansion, respectively. Globally, an important exception is a trade-off between overly compact urban expansion and UGG. Moreover, land, economic, technological, and greening factors exhibit spatially non-stationary associations with UGG. Our findings offer insights into dynamic scaling laws in urban microsystems and underscore the critical role of suitable urban compactness and targeted carbon-reduction policies in achieving sustainable urban planning.