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IMPACT ON
THE ENVIRONMENT
source: Chrisna du Plessis and Kaixun Sha, “Rapidly Populating Cities/ Rapid Urbanisation”, 2002 [ www.sb05.com/academic/
14_IssuePaper.pdf]
www.careinternational.org.uk/
resource_centre/urban/urbanisation
_of_poverty.doc
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Rapid urbanisation places economic, social and environmental pressure on cities. These pressures are particularly keen in the low-income countries of Latin America, Africa and Asia… - one of the biggest problems facing many cities in low-income countries is that the rate of economic growth, and subsequently of per capita income, does not keep pace with the rate of population growth. A poor population means low payment levels for services. This reduces the rates base of a city, thus reducing the resources available to provide adequate levels of services at a speed that matches the population’s growing needs;
- when there are more people demanding services than people paying for them, municipalities are unable to provide these services. Even where people can afford to pay for services and infrastructure like housing, the growth in demand often exceeds the ability of local governments to respond to this demand quick enough;
- this situation forces people to provide their own, often illegal, solutions. The creation of informal settlements, illegal connections to existing services, and occupation of sensitive areas like riverbanks and steep hillsides leads to social tensions and a number of safety concerns such as increased vulnerability to both natural and man-made disasters;
- urbanisation concentrates and thus compounds the environmental impact of human settlements: increased water run-off leading to higher flood risks and pollution of groundwater, increased water consumption due to higher standards of services, increased concentrations of air and water pollutants, and the degradation or complete loss of arable land and biodiversity, are but a few of the environmental impacts of urbanisation;
- on a city-wide scale, the environmental impact of the non-poor as a result of their consumption levels and patterns far exceeds that of the poor. Because of their low levels of resource consumption, and their tendency to re-use and recycle, poor communities also have a negligible distal environmental impact, compared to more affluent communities;
- however, in low-income urban areas, environmental problems are a major cause of disease and death, both because of the proximity of the problem (pollution of drinking water from rivers, indoor air pollution, disease vectors like rodents and fleas, open sewage, etc.) and the lack of accessible health facilities in these areas.
Urban-based economic activities account for more than 50% of GDP in all countries, and up to 80% in more urbanised countries in Latin America, or more in Europe…- as a consequence, although cities are taking up only 4% of the earth's land, they use huge amounts of natural resources, such as energy, water, minerals, and often the best lands. As cities become more affluent, the environmental burdens tend to become more diffuse, delayed and indirect (climate change, ozone depletion, etc.);
- the difference of the environmental impact of a developed and developing country is significant: a city of 650.000 inhabitants in North America would require 30,000 km² to maintain its present consumption levels while a similar sized city inIndia would only need 2,800 km²;
- on average, slum dwellers in New Delhi, India, require only 0.8 hectares (2 acres) of land per capita to maintain their minimal lifestyles, while Americans in Boston or New York need 8.4 hectares (21 acres) of land per capita to support their consumption levels;
- cities impact on ecosystems that are closely located to the city borders. Some of the ecosystems that cities are impacting on, including wetlands, woodlands, lakes, and swamps, have national, regional or even international importance from a biodiversity point of view;
- cities have great impact on water bodies, rivers, lakes and coastal areas. Approximately 60% of the world's population lives within 100km of the coast, an area that counts for only about 25% of the land mass. By 2025, over 80% of the largest 30 cities in the world will be in developing countries, and the majority will be coastal megacities.
- many coastal cities discharge their sewage, industrial effluent and other wastes into rivers and oceans. For example, in South Africa alone, there are some 63 ocean out-falls along the coast discharging approximately 800.000 m³ of sewage and industrial effluent into the sea every day;
- waste water streams contain nitrogen and phosphate which contribute to eutrophication, where algae and other plants flourish on the nutrients and by doing so deplete all the oxygen from the water, suffocating other plants and animals;
- one of the effects of sewage pollution by coastal cities is the destruction of coral reefs. A case in point is Singapore where the land area has been increased by more than 10% in the past 35 years. Sediments are continually being stirred up by the massive amount of shipping, damaging corals directly by settling on them and also by reducing the amount of light energy corals receive;
- coastal cities also contribute to the global depletion of fish stocks. More than 90% of the world's marine harvest comes from coastal waters and much of it is brought ashore in cities where the fish are being sold.
The challenge for cities in low-income countries is how to improve the immediate quality of the living environment for those living in informal settlements…- few countries in developing country cities have adequate sewerage systems. Worldwide, 2/3 of the sewage from urban areas is pumped untreated into lakes, rivers and coastal waters;
- air pollution in cities in developing countries has reached dangerous levels: 13 of the 15 cities with the worst air pollution in the world are in Asia. Levels of smoke and dust emitted from leaded gasoline and coal burning in Beijing and Shanghai in China are often 5 times the levels in most European and North American urban areas;
- WHO estimated that worldwide 1.5 billion urban dwellers face levels of outdoor air pollution that are above the maximum recommended level. More than 70% of deaths from outdoor air pollution occur in the developing world. In India alone air pollution causes an estimated 40,000 premature deaths each year;
- the ozone concentration in Mexico City, measured in 1995, was 10 times the natural atmospheric concentration. The World Health Organisation (WHO) estimated that worldwide 1.5 billion urban dwellers face levels of outdoor air pollution that are above the maximum recommended levels;
- indoor air pollution is particularly a health problem in rural households, however cities - especially informal settlements – are increasingly concerned. Worldwide, almost 3 billion people rely on biomass fuels -mostly wood, charcoal, and animal dung for household cooking and heating. In China, India and sub-Saharan Africa more than 80% of households use biomass fuels for cooking.
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