Urban Population Structure Differentiation: Reshaping the Global Urban Competition and Governance Landscape

The process of global urbanization is reshaping the human spatial form at an unprecedented speed, but its underlying driving forces are not uniform. Recent detailed annual estimates of age and gender population structures for over ten thousand cities globally reveal a profound structural paradox: urban population changes exhibit high heterogeneity rather than a unified global narrative. This imbalance is key to understanding the current global urban competition landscape, assessing urban resilience, and formulating future urban strategic blueprints.

From a macro perspective, it is projected that about two-thirds of the population will be concentrated in cities by 2050. However, the center of this growth is not evenly distributed. Low- and middle-income countries (LMICs) bear the vast majority of urban population growth, making these cities the testing grounds for global population migration and urbanization, while simultaneously exposing them to immense pressure in terms of infrastructure, social services, and climate adaptation. Research indicates that the driver of population growth in these rapidly expanding cities is a complex mixture of natural increase and net migration, and the gender structure differences in this migration, particularly the male surplus observed in the Middle East and North Africa, clearly reflect the tensions in labor mobility and geopolitical economy.

These differences in population structure have multiple strategic implications for urban development. First, they directly determine a city's potential for economic growth. A healthy "demographic dividend" depends on a suitable working-age population structure; conversely, population aging can instantly overwhelm social security systems while changing the nature of urban consumption patterns and labor supply. Second, population structure is a sensitive indicator of exposure to urban climate risks. The vulnerability of different age groups is vastly different; for example, the risks faced by the elderly and pregnant women during extreme heat or flood events are disproportionate. Therefore, integrating population structure with climate change risk models is a prerequisite for building climate-resilient urban defense systems.

A deeper structural contradiction lies in the way existing planning and policies treat the "national average," which masks the intense internal differentiation within cities. Many countries, lacking high-resolution, city-level population census data, can only rely on macro estimates at the national level. This data gap makes it difficult for policymakers to accurately identify the "key cities" that require differentiated interventions—those cities exhibiting significant characteristics in terms of economic vitality, environmental exposure, and governance capacity.

This spatial imbalance also profoundly affects the distribution of power and regional economic competition between cities. In many developing countries, the rise and fall of urban agglomerations often depend on their ability to absorb regional populations and capital. When the emergence of some developed cities coexists with the decline of others, this difference further solidifies the structural gap between cities in the Global South and high-income cities. This is not just a problem of economic disparity; it is a fork in the road for the evolution of urban civilization—will it move towards sustainable, inclusive development, or will it be defined by the gravitational pull of a few monolithic, mega-cities?

Therefore, the paradigm of urban studies urgently needs a fundamental shift.Therefore, the paradigm of urban studies urgently needs a fundamental shift. Future urban strategies must move beyond mere indicators of "urban size" or "total population" and pivot towards the fine-grained monitoring of internal urban dynamics, spatial heterogeneity, and the coupling between population structure and environmental risks. This requires us not only to have more detailed urban population data but also to establish an interdisciplinary analytical framework that integrates climate science, socioeconomic models, and spatial politics. Only by viewing the "differentiation" of urban populations as a global structural challenge can we provide forward-looking strategic guidance for the long-term stability and sustainable evolution of the global urban system.