Diverging trajectories of built-up land dynamics for country groups by income until 2100

The area of built-up land per capita (BPC) is a key indicator of land use efficiency, varying by an order of magnitude between countries. While previous studies have examined the effects of GDP and population, the influence of other socioeconomic factors on BPC has remained unclear, as well as potential differences across groups of countries by income. Using a fixed effects regression model, we analyze national-level BPC from 1985 to 2020 and identify significant relationships with GDP per capita, population density, human capital, household size, income distribution, and governance. Future projections under different Shared Socioeconomic Pathways scenarios (SSPs) suggest that global BPC will increase between 1.2 times (SSP4) and 2.7 times (SSP5) until 2100. Combined with population dynamics, this rise will result in a substantial increase in total built-up land demand. The projected variations between scenarios in BPC are more pronounced in low- and middle-income countries than in high-income countries. The disparities in built-up land across countries narrow under SSP1 and SSP5 but remain highly uneven in other scenarios. These findings underscore the impact of socioeconomic factors in builtup land projections and highlight trade-offs between human well-being, equity, and urban land consumption.