11.2 Patterns and trends in global urbanization

Urbanization is transforming our world. Cities are growing fast, especially in developing regions. By 2050, nearly 70% of people will live in urban areas. This shift brings opportunities and challenges for economic growth, social change, and the environment.

Megacities are booming, with 33 now housing over 10 million people each. These urban giants drive economies but face big issues like inequality and pollution. How we manage urban growth will shape our future, from climate risks to quality of life.

Global Urbanization Trends

Rapid Urban Growth and Projected Increase

• The global urban population has grown rapidly over the past century, from around 15% in 1900 to over 50% today
  • Projected to reach nearly 70% by 2050
  • Urban growth is increasingly concentrated in developing regions (Asia and Africa projected to account for nearly 90% of the 2.5 billion global urban population increase between 2015-2050)

Regional Variation in Urbanization Rates

• Urbanization rates vary significantly across world regions
  • Latin America, the Caribbean, North America, and Europe are the most urbanized
  • Africa and Asia remain the least urbanized but are urbanizing most rapidly

Urbanization and Economic Development

• The level of urbanization is highly correlated with economic development
  • High-income countries are far more urbanized on average than low- and middle-income countries
  • Urbanization is associated with higher incomes, lower fertility rates, and greater access to education and health services

Urbanization Drivers in Developing Countries

Rural-Urban Migration

• Rural-urban migration is a major contributor to urban growth in developing countries
  • Driven by both "push" factors like rural poverty and "pull" factors like urban economic opportunities
  • Can also result from displacement due to conflict, disasters (earthquakes, floods), or development projects (dam construction)

Natural Population Increase

• Natural population increase, resulting from an excess of births over deaths, is becoming an increasingly important driver of urban growth
  • Fertility rates are declining and the share of growth from migration is decreasing
  • Contributes to expansion of urban administrative boundaries to encompass surrounding settlements and reclassification of rural localities as urban

Globalization and Economic Transformation

• Globalization and the growth of international trade and investment have spurred export-oriented industrialization and urban growth in many developing countries
  • Cities serve as hubs for manufacturing (garment factories), services (call centers), and trade (ports)
  • Agglomeration of people, skills, and enterprises in cities generates economies of scale and knowledge spillovers that drive innovation and economic productivity

Megacities and Urban Systems

Emergence and Growth of Megacities

• Megacities are defined as urban agglomerations with populations of 10 million or more
  • The number of megacities has grown from 10 in 1990 to 33 in 2018, mostly located in the global South (Asia, Africa, Latin America)
  • Examples include Tokyo, Delhi, Shanghai, São Paulo, and Mexico City

Functions and Challenges of Megacities

• The growth of megacities is driven by their function as national and regional economic hubs
  • Often serve as capitals or centers of industry, finance, and trade
  • Highly interconnected with global flows of capital, goods, and people (airports, stock exchanges, multinational corporations)
• The rapid growth of megacities often outpaces governance and infrastructure provision
  • Leads to proliferation of informal settlements (slums, favelas), strains on services (water shortages, traffic congestion), and environmental hazards (air pollution, waste management issues)

Megacities and Global Risks

• Megacities are increasingly vulnerable to the impacts of climate change due to their coastal locations, high population densities, and concentrated infrastructure
  • Sea level rise threatens low-lying areas (Jakarta, Manila)
  • Extreme heat and water scarcity pose public health risks (Delhi, Cairo)
  • Large urban populations concentrated in hazard-prone areas are vulnerable to natural disasters (earthquakes in Mexico City, cyclones in Dhaka)

Urbanization Impacts: Environmental, Economic, and Social

Environmental Implications

• Urban sprawl and low-density development patterns have negative environmental consequences compared to compact urban forms
  • Higher energy use and vehicle emissions contribute to air pollution and climate change
  • Loss of agricultural land and natural habitats (wetlands, forests) reduces biodiversity
• Rapid, unplanned urbanization can lead to growth of informal settlements lacking basic services
  • Inadequate clean water, sanitation, and waste management have negative health impacts (waterborne diseases, respiratory illnesses)
  • Environmental degradation (deforestation for fuelwood, dumping of untreated sewage) affects both urban and surrounding areas

Economic and Social Consequences

• Urbanization is associated with economic benefits but also challenges
  • Cities generate a large share of GDP and provide opportunities for employment, entrepreneurship, and upward mobility
  • However, urban growth can also lead to heightened inequality (slums alongside gated communities), crime, and social fragmentation
  • Congestion, pollution, and high costs of living (housing, transport) affect quality of life, especially for the urban poor
• Differences in the speed and nature of urbanization across countries shape development outcomes
  • Planned, well-managed urbanization with adequate infrastructure and services promotes sustainable, inclusive growth
  • Rapid, haphazard urbanization without strong institutions or resources can exacerbate poverty, inequality, and instability