Scaling laws of CO2 emissions during global urban expansion

Abstract Continuous urbanisation, rising energy usage, and CO 2 emissions challenge global sustainability. Current understanding is fragmented due to regional research differences and conflicting data sources. We used RS and GIS technologies to create a comprehensive dataset on global urban CO 2 emissions (2000−2020). Besides population and density, we included land area size and physical compactness. Our findings indicate that higher population density may reduce emissions, physical compactness can increase them, and land area size influences emissions more than population size. Thus, strategic planning is essential for emission reduction. We found varied relationships between per capita emissions and population density and between emission intensity and compactness. Different cities face unique challenges based on location and development stage. Developing economies, especially in Africa, face significant challenges as emission scaling shifts from sublinear to superlinear with urbanisation. Large cities should reduce fossil fuel use and adopt eco-friendly technologies, while smaller cities should enhance emission efficiency.