Toward more reliable, complete, and equitable global urban land use efficiency assessments

Improving Urban Land Use Efficiency (LUE) can curb urban sprawl, protect farmland and ecological spaces, and promote low-carbon, intensive development models. Although numerous studies have been conducted, uncertainty and bias in LUE assessments—stemming from data sources, LUE calculations, and trend analysis methodology—has rarely been investigated. After a series of tests, here we propose a reliable, comprehensive, and equitable framework, which uses Built-Up Area per capita (BUP) metrics and provincial population data, along with time-series analysis tools, to assess LUE trends. Our global evaluation reveals that 79.6% of provinces saw significant BUP growth from 1985 to 2020, with an average increase of 15 m² per capita per five years - a trend that challenges progress toward Sustainable Development Goal 11.3. Considerable—and widening—disparities in BUP are observed across provinces and countries. In 2020, the BUP in some high-income countries was thirty times greater than in low-income countries, while the latter exhibited higher BUP growth rates—likely due to their smaller initial base. However, they could still be considered inefficient in land use if assessed solely based on growth rate metrics. The study highlights the importance of reliability, completeness, and equity in global assessments and in building global criteria. The built-up area per person has grown significantly in 79.6% of global provinces from 1985 to 2020, indicating widening disparities of land use efficiency across provinces and countries, according to a new framework integrating provincial population data.