MEGACITIES IN THE CONTEXT OF ECOLOGY

Transcription

1 MEGACITIES IN THE CONTEXT OF ECOLOGY Human ecological footprints Population growth, urban/rural shifts, and mega cities Ecological sustainability: - climate change - disease - food and water

2 WWF Definition of Ecological Footprint The biologically productive area to produce: food and wood (cropland, grazing land, forest), room for infrastructure, absorb CO 2 from burning fossil fuels [BUT omits: water consumption, release of pollutants.]

3

4

5

6 Paradoxes and Ethical Country Egypt Dilemmas ecological footprint per person 1.70 biological capacity per person 0.64 Sweden World Average

7 The Ecological Footprints of Cities Today, cities occupy roughly 2% of the Earth s s land surface. BUT they consume more than 75% of its resources.

8 LONDON area occupied: ~1,500km 2 footprint (supplies and waste disposal): ~20 million km 2 London is home to 12% of UK population. BUT it uses the equivalent of ALL the UK s productive land (of course, land used to supply its food extends globally).

9 Human Population Growth Has not been simply exponential Three phases of rapid change/growth Agricultural Revolution,, beginning 10,000 years ago, slowed by rises of diseases in urban aggregations Scientific/Industrial Revolution in the West, beginning ~ Spread of science-based public health, twentieth century

10 Human Numbers Time Population ~ billion ~ billion ~ billion today 6.3 billion 2050 ~ 9 billion

11 Urban-Rural Shifts 95% of the buildout of human numbers will occur in the urban areas of developing countries (whose populations will double, to 4 billion, by 2050)

12 From arguably the first big city,, Ur, in Sumeria, 4,000 years ago (~35,000 inhabitants), to Tokyo today (~26 million), cities have consistently buried more people than they have given birth to.

13 The urban Fraction of Global Population Time Fraction 1700s less than 10% % today 50% %

14 The Rise of Big Cities Time million Number of cities with populations over today at least 550

15 TOP 12 MEGACITIES IN 2015? City Tokyo Mumbai Delhi Mexico City Sao Paolo New York Dhaka Jakata Lagos Calcutta Karachi Buenos Aires Population (millions) (estimated)

16 By 2020, an estimated 23 cities (roughly half in Asia) will have passed the 10 million mark. Around 600 cities will have one million or more inhabitants.

17 NOT ALL CITIES ARE MEGA ¾ of population growth will end up in second-tier cities (population less than 8 million) In China, for example, officially 193 cities in 1978; 640 today.

18 SLUMS AND (SOME, NOT ALL) MEGACITES In the ninteenth and early twentieth century slums in Western cities, mortality rates were appalling. With better understanding of infectious disease (vaccination; dynamics of transmission), this is not generally true today.

19

20 Infant mortality today Annual total births: Infant deaths: ~ 130 million ~ 10 million

21 Another difference Earlier slums resulted largely from industrialisation, drawing workers to cities (usually the centre), and tending to slow or even reverse migration to countryside as prosperity grew.

22 Today, in some places (e.g. China) the pressures of industrialisation are similar. But in other places (sub-saharan Africa, Latin America, Middle East, parts of Asia) urbanisation is radically decoupled from industrialisation, and even from development as such. This perverse urban boom contradicts orthodox economic models. So instead of being a focus for growth and prosperity, some cities have become dumping grounds for surplus populations, working in unskilled and unprotected trades and informal services industries.

23 Arguably, the well-intentioned I.M.F. structural Adjustment Programs have, over the past 20 years, increased urban poverty and slums, increased exclusion and inequality, and weakend cities as engines to promote economic growth.

24

25

26 Three Worlds (2000) Population (billions) GDP (trillion ppp$) Poor Transitio n Rich Industrial energy (tw) Biomass energy (tw) Fossil carbon (billion metric tons C per year)

27 Bacterial and viral diseases are the price humanity has paid to live in large and densely populated cities. Virtually all the familiar infectious diseases have evolved only since the advent of agriculture, permanent settlement and the growth of cities.

28 Most were transferred to humans from animals especially domestic animals. Measles, for instance, is akin to rinder- pest in cattle; influenza came from pigs; smallpox is related to cowpox. Humans share 296 diseseases with domestic animals. From John Reader, the author of Cities (Heinemann, 2004)

29 More recently: HIV/AIDS came from bushmeat trade (HIV-I, I, chimps; HIV-2, monkeys) SARS from internationalisation of bushmeat trade (civets)

30

31

32 The time has come to close the book on infectious diseases W.H.Stewart U.S. Surgeon General, 1967

33 The Green Revolution, ca Food production x 2 (up 100%) Extra land used x 1.1 (up 10%) Global population x 1.6 (up 60%) Nitrogen fertilizer x 7 (up 600%)

34 Could not feed today s s population with yesterday s s agriculture BUT, signs of plateau. Need Doubly Green Revolution (More production, More environmentally friendly)

35 Supplies of water Global patterns of use 10% domestic 21% industrial 69% agriculture

36 Today: 29 countries, with 0.5bn people, are in water deficit By 2020: : 50 countries, with 3 bn people, will be in water deficit

37

38

39 MEGACITIES IN THE CONTEXT OF ECOLOGY Human ecological footprints Population growth, urban/rural shifts, and mega cities Ecological sustainability: - climate change - disease - food and water