Mega-Cities: Comprehensive Study Notes

Global Population & Urbanisation Trends

• World population currently rising by $86\,\text{million}$ people per year; momentum will keep growth positive for several decades because large cohorts have not yet reached child-bearing age.

• Distinct regional patterns:

  • Developed regions: population has stabilised and is projected to fall slightly in the next century.

  • Developing regions: population is rapidly increasing (see Fig. $1$ – growth curves for “Developed regions” vs. “Developing regions”).

• Urbanisation (share of people living in towns/cities):

  • Between $1990$ and $2025$ the urban population is expected to double from $2.5\,\text{billion}$ to $5\,\text{billion}$.

  • $90\%$ of this increment will occur in Africa and Asia.

Definition & Evolution of Mega-Cities

• Mega-city = urban agglomeration whose population exceeds $8\,\text{million}$.

• Historical milestones (Table $1$):

  • $1950$: only $2$ mega-cities – New York & London.

  • $1990$: $20$ mega-cities, $14$ in the developing world.

  • $2000$ (projection): $25$ mega-cities, $19$ in the developing world.

• Growth comparison: although mega-cities are huge, the fastest percentage growth usually occurs in “million-cities” (population $1–10\,\text{million}$).

Spatial Distribution: Coastal vs Non-Coastal Cities (Table $2$)

• $108$ coastal cities (population $1–10\,\text{million}$) vs $159$ non-coastal in $1995$.

• Among settlements >$10\,\text{million}$, coastal locations dominate (no exact count given, but described as “disproportionate”).

• Implication: coastlines experience high environmental pressure – habitat loss, biodiversity decline, erosion of natural storm-protection systems.

Current Urban Growth Rates (Selected Examples)

• Dhaka $7\%\;\text{yr}^{-1}$

• Lagos $5.6\%\;\text{yr}^{-1}$

• Delhi $4.6\%\;\text{yr}^{-1}$

• Anticipated African national urban population growth: Kenya $6.2\%$, Tanzania $6.0\%$.

• Latin American mega-cities show a marked slow-down (Fig. $2$) with annual growth falling in successive decades for Buenos Aires, Mexico City, Lima & Rio de Janeiro.

Environmental Challenges in Developing-World Mega-Cities

• Water access: >$1\,\text{million}$ residents in Jakarta lack piped water/wells; $30\%$ depend on an over-drawn aquifer → land subsidence.

• Air quality: Jakarta exceeds WHO particulate limits for $8$ months per year; similar chronic pollution in Mexico City, São Paulo, Calcutta & Bombay.

• Waste & sanitation:

  • Lagos, Jakarta, Lima: worst solid-waste collection records.

  • Bangkok, Manila, Dhaka: acute sewage-disposal problems.

  • Mexico City: aquifer over-abstraction has caused $7.5\,\text{m}$ subsidence in $100$ yrs; aquifer also contaminated by sewage.

• Coastal siting exacerbates ecosystem degradation (mangroves, coral, wetlands).

Environmental & Resource Issues in Developed-World Mega-Cities

• Primary concern shifts from local shortages to massive per-capita resource consumption and resulting regional/global impacts (GHG emissions, ecological footprint).

• Air pollution still a direct health issue (e.g.
  Los Angeles, Tokyo), but often better regulated than in developing cities.

Common Social Problems

• Violence, crime, drug abuse present in both rich and poor mega-cities; not strictly proportional to size but influenced by inequality and governance.

• Dual-city phenomenon: pronounced class segregation → elite enclaves vs vast low-income zones.

• Multi-jurisdictional governance: no Latin-American mega-city has a single all-city authority; coordination is weak.

Nine Key Drivers of Mega-City Growth

1. Colonial foundation of coastal cities by European powers (e.g.
   Lima, Buenos Aires, Rio de Janeiro $1763$).

2. Port & trading functions for specific commodities (Shanghai – cotton/silk; São Paulo – coffee).

3. Capital-city designation or administrative reassignment (Dhaka: population jump from $0.43$ M in $1950$ to $2.3$ M in $1975$, now growing $7.25\%\,\text{yr}^{-1}$).

4. Post-independence industrialisation & import-substitution favouring major urban nodes (Mexico City, Rio, Buenos Aires, Indian metros).

5. Post-war modernisation (1930s Great Depression & WWII) stimulated local industry and wealthy domestic markets in Latin America.

6. Declining urban & rural mortality through public-health advances raised natural increase and lengthened life expectancy.

7. Rural-to-urban migration under classic push–pull forces:

   • Lack of land, agrarian mechanisation, conflict, famine (push).

   • Jobs, services, perceived higher living standards (pull).
     Example: contributed $50.8\%$ of Argentina’s urban growth $1947–1960$.

8. Settlement laws (e.g.
   China’s household registration – “Entitled” urban vs “Non-Entitled” rural) created privileged urban status → migration pressure.

9. Globalisation & foreign direct investment concentrate in biggest cities: Bangkok $86\%$ of Thailand’s GNP in finance/real estate, $74\%$ of manufacturing; Lagos hosts $40\%$ of Nigeria’s highly-skilled labour though only $5\%$ of population.

Advantages of Mega-Cities (Table $3$)

• Agglomeration economies: clustering of industries/finance gives ready markets, labour, external linkages.

• Infrastructure & services usually superior to rural areas (roads, power, piped water, education, health, family planning).

• Health outcomes: urban infant-mortality lower, life expectancy higher (Brazil $75.4/1000$ urban vs $107.5/1000$ rural in $1986$; Peru $57.9/1000$ vs $104.1/1000$).

• Informal sector offers entrepreneurial niches and absorbs surplus labour.

• Auto-construction/self-help housing allows incremental expansion & rental income.

• Dense social/employment networks in shanties underpin informal economy.

• Grass-roots governance potential – e.g.
  Bombay’s chawls; service privatisation (supported by World Bank) can relieve public budgets.

• “Concentrated de-concentration” policies push firms to city edge to develop peripheral sub-centres (Buenos Aires example).

Disadvantages Intensified by Size

• Migrant magnet effect outpaces job creation & infrastructure (e.g.
  Lagos as Nigeria’s primary city).

• Unequal service distribution: in São Paulo $40/54$ public hospitals located in wealthy districts → poor health outcomes for majority.

• Severe environmental hazards (water, air, waste, land subsidence, coastal habitat loss).

• Informal sector often harassed, lacks credit/support, and adds little to national revenue.

• Urban sprawl via motor-car use & spontaneous settlement (favelas, pueblos jóvenes, bustees) undermines formal planning, inflates land prices (São Paulo).

• Hazardous land occupation: landslides in Rio’s Rocinha; flooding in Calcutta.

• Administrative fragmentation complicates metropolitan governance.

• Social dualism – polarised wealth & spatial segregation reinforce inequality.

Case Study 1: Bombay (Mumbai)

• Population trajectory (Fig. $3$): >13\,\text{million} in $1994$; projected $15\,\text{million}$ by $2000$.

• Physical setting: $180\,\text{sq mi}$ formed by reclaiming $7$ islands; Western Ghats crossed by rail ($1850s$).

• Historical growth: English deep-water port (received $1661$); cotton export to Lancashire after $1850$.

• Present social fabric:

  • $\approx50\%$ residents live in slums/chawls; many homeless by UK standards.

  • Dharavi: <1\,\text{sq mi}; $\sim700,000$ people; $77\%$ households average $5.3$ persons/room.

• Economy: vibrant informal industries – jewellery, pottery, cloth & a major recycling sector.

• Infrastructure deficits:

  • $2\,\text{million}$ people without sewers; city produces $5,000\,\text{t}$ rubbish/day.

  • $550\,\text{million gal}$ drinking water piped $100\,\text{mi}$ daily.

  • Untreated sewage discharged into Arabian Sea; industrial pollution → respiratory/skin diseases.

Case Study 2: Shanghai

• Early development: regional port; $1.2\,\text{million}$ by $1910$.

• Japanese occupation $1937–1949$ caused foreign exodus.

• Communist era: anti-urban & anti-foreign trade policies; many industries relocated; nationalisation.

• Household registration system: “Entitled” urban residents received subsidies → migration surge; crackdown in late $1950s$.

• Cultural Revolution forced youth/skills to rural areas → under-urbanisation.

• Post-Mao reform ($1978$ on): foreign investment welcome; population growth $3.8\%$ p.a. ($1985–1993$).

• “Floating population”: large, often illegal, unregistered migrants complicate housing & service planning.

• Economy: $67\%$ industrial-output growth $1990–1993$ but low-skill factories relocating outward; unemployment $15–20\%$; $40\%$ families lack basics.

Case Study 3: São Paulo

• MASP = $39$ municipalities; $\sim17\,\text{million}$ residents; delivers $30\%$ of Brazil’s GNP; $\frac{1}{3}$ of labour force in manufacturing → 2nd-largest industrial city worldwide.

• Historical stages:

  • Founded $1554$; minor until late $19^{\text{th}}$ century (Rio dominant).

  • Coffee boom → annual growth $13.9\%$; social stratification via employer-provided housing.

  • $1910–1930$ elite moved to Higienópolis; Haussmann-style boulevards displaced poor to periphery.

  • Import-substitution industries $1920–1930$; further industrialisation $1960s–1980s$ plus nationwide transport upgrades.

  • $1980s$: major banks relocated from Rio; but economic crisis triggered industrial de-concentration.

• Four core–periphery dynamics (mid $20^{\text{th}}$ century):

  1. Falling density: $110\rightarrow24.5$ persons/ha ($1914\rightarrow1960$); peripheral growth $10\%\,\text{yr}^{-1}$.

  2. Class segregation: wealthy centre vs poor periphery.

  3. Rising home-ownership overall ($19\%$ → $53.8\%$ $1920\rightarrow1970$) via self-build in periphery & condos in core.

  4. Dual transport: buses for poor, cars for rich.

• Economic crisis metrics (Table $4$): unemployment rose from $12.4\%$ ($1985$) → $15.4\%$ ($1993$); absolute unemployed $0.8\,\text{M}$ → $1.224\,\text{M}$.

• Housing: $\approx\tfrac{2}{3}$ of homes in favelas by $1992$.

• Environmental stress:

  • WHO particulate & CO limits breached $\ge6$ months/yr.

  • $800\,\text{t}$ raw sewage plus industrial effluent enter River Tietê daily.

  • $28\%$ homes lack piped water; $50\%$ not sewered.

Synthesis: Towards Sustainable Mega-Cities

• Essential policy thrusts:

  • Community participation (Shanghai, Guangzhou) for planning legitimacy.

  • Legalise informal settlements; extend tenure security to encourage upgrading.

  • Facilitate micro-credit & recognise informal enterprises to integrate them into formal economy.

  • Invest in basic urban services (water, sanitation, waste, mass transit) before further outward expansion.

  • Narrow urban-rural and intra-urban income gaps to temper migration “pull”.

  • Apply stricter environmental standards (vehicle emissions, industrial effluent) & protect coastal ecosystems.

  • Promote “concentrated de-concentration” / polycentric development to share growth regionally.

  • Strengthen metropolitan governance frameworks to coordinate across multiple municipalities.

Key Figures & Tables Recap

• Fig. $1$: World population growth $1750–2150$ showing divergence of developed vs developing regions.

• Table $1$: Evolution of >8\,\text{M} cities $1950, 1970, 1990, 2000$.

• Table $2$: Coastal vs non-coastal >1\,\text{M} cities ($1995$).

• Fig. $2$: Latin-American city growth rates by decade $1950–1990$.

• Table $3$: Advantages & disadvantages of mega-cities.

• Figs. $3–5$: Population growth curves for Bombay, Shanghai & São Paulo respectively; Table $4$ unemployment data for São Paulo.

Ethical & Practical Implications

• Equity: spatial segregation fosters social exclusion → moral imperative to create inclusive service delivery and economic opportunity.

• Health: uncontrolled pollution violates right to health; policy must balance growth with public-health safeguards.

• Environmental justice: poorest groups often inhabit hazard-prone land yet contribute least to pollution – call for remedial infrastructure & land-use planning.

• Global responsibility: developed-world mega-cities’ consumption patterns drive worldwide ecological impacts (climate change) – need for sustainable lifestyles & technology transfer.