Today in the United Kingdom 30% of the shopping takes place out of the city and this numbers will be going up as long as the suburbs are expanding and land is more and more expensive in city centres traffic problems grow and competition between businesses is retained.
An increasing proportion of the world’s population is living in urban areas: at the beginning of the 21st century, this proportion was about half, with around one-seventh in cities with 1 million or more inhabitants. The urban environment might be considered the opposite of the natural environment, since it concentrates so many people, buildings, and economic activities and their supporting infrastructure such as roads, water pipes, drains, and electricity and telephone systems. In larger cities, central business districts, downtown areas, and industrial estates may have little visible that can be associated with the natural environment. Human interventions have so radically shaped their environment that they seem far removed from natural processes and resources. Other parts of cities, however, seem less removed—for instance parks, green belts, rivers, coastlines, or residential areas with large gardens and plenty of open space. However, all urban centres remain dependent on natural resources and on natural processes for disposing of their wastes.
Each professional discipline brings its own concerns to addressing environmental problems in urban areas. Environmental health specialists are particularly concerned about the diminution of environmental hazards; in most urban areas in Africa and many in Asia and Latin America, this centres on the control of infectious and parasitic diseases whose incidence and transmission is often increased by overcrowding, poor-quality housing, and inadequate provision for water supply, sanitation, and drainage. Ecologists tend to focus on the massive disruption that large urban centres and the materials they need usually bring to flora and fauna and the wider ecosystems of which they are part. Political scientists may focus on environmental justice, highlighting the ways in which the wealthy and powerful can obtain high-quality living environments within cities while the poor and non-powerful face numerous environmental hazards. The different disciplinary perspectives are much needed to make sense of the complex interweaving of natural and built elements within urban centres and of the climatic, social, economic, and political factors that influence them.
II THE DIVERSITY OF URBAN ENVIRONMENTS
İstanbul, Turkey Situated on the Bosporus Strait, İstanbul is a major port and the largest city in Turkey. The walls seen here are the remains of the original city, built in ad 324 by Constantine I of Rome.Turkish Tourism Office
While all urban centres share certain environmental characteristics, their size, built forms, and spatial configurations are also very varied. While it is usually economic and political factors that determine a city’s location and size, its buildings and their location and organization within neighbourhoods and the wider city are also much influenced by characteristics of the site, climatic conditions, and resource availabilities (especially building materials and fresh water). In many cities, it was particular local characteristics that encouraged the city’s foundation there or subsequent expansion—for instance, good port facilities on rivers or the coast (e.g. Southampton, Buenos Aires), a fertile river valley (Vienna, St Louis), mineral resources nearby (Johannesburg, Potosí), a site with a healthy and pleasant climate (Christchurch, San Francsico), or easy defensibility (İstanbul, Quebec).
However, it has often proved difficult to protect the environmental advantages of city sites, when cities grow in population. Many cities have outgrown the natural advantages of their site—as, for instance, in Rio de Janeiro and Caracas where expanding populations have had to build homes on hillsides that are often too steep or unstable for safe residential development. The very large increases in the generation of air pollution have revealed the limitations of certain city sites for the dispersion of pollution. For instance, the site of Mexico City is of considerable natural beauty, well suited to a major city; it had been chosen by the Aztecs as the location of their great city Tenochtitlán, before the arrival of Europeans. Until relatively recently, it was regarded as a pleasant city site. Now it has serious problems of air pollution because the high altitude, lack of winds, and shape of the valley in which it is situated make the site ill-suited to a very large city with a high concentration of industries and motor traffic, unless emissions from those sources are strictly controlled. Mexico City is also one among many cities where the demand for fresh water has outstripped the capacities of local supplies, or local sources have become too polluted to use. Many major cities that were once adequately served by local ground and surface water sources now have to import water from more distant catchment areas, often with damaging ecological consequences for these areas.
Cities have always been much influenced by the knowledge and culture of their inhabitants. This can be seen both in the form of buildings and in the design of neighbourhoods and public spaces. These characteristics were shaped by local climatic and geographical conditions; building design, the materials used, and the organization of public and private spaces helped to moderate extreme temperatures, provide protection from rain and wind, and, where needed, limit risks from natural hazards. However, these cultural differences are disappearing. In many major cities, it is only the historic centres or older settlements engulfed by the urban expansion that retain the characteristics that, for instance, distinguish the Islamic city from the Hispano-American city. This diversity is being eroded as modern building designs and materials become internationalized and as the ready availability of fossil fuels and electricity allows temperatures within city buildings to be controlled, regardless of building design and climatic conditions. Poverty is also eroding these cultural differences in many cities in Africa, Asia, and Latin America. Here, the illegal and informal settlements in which so many city inhabitants live also present a more uniform picture, as widespread use is made of temporary materials for buildings, and as homes are squeezed on to any land site from which the inhabitants might escape eviction.
Motor vehicles are now a major influence on the environment and spatial form of virtually all cities. Roads, highways, parks, and garages have reshaped older urban environments and imposed their logic on new ones, especially where a high proportion of urban households own a car. Motor vehicles can become a dominant influence, with roads and associated facilities taking up a third or even half the total city area. Increasing levels of car ownership and use also encourage an ever-increasing separation between homes and workplaces and a low-density urban sprawl. Growing vehicle numbers can radically reshape cities even where less than a third of households own private cars, especially in cities where central districts were developed before the advent of motorized traffic. Most of the major cities of Europe, North Africa, Asia, and Latin America were already important cities in the first half of the 20th century (many were important 200 years ago) so their central areas have road systems that are now too small to accommodate a widespread use of private cars.
The quality of the urban environment can also differ greatly between different areas of any city. In many cities, this is partly the result of town planning, with zoning and land-use regulations encouraging a concentration of industries, shops, middle-class housing, and low-income or public housing in particular areas. However, income differentials are often a more potent cause. Thus there are dramatic contrasts in housing and environmental quality between different areas of most cities in Africa, Asia, and Latin America, even though there is little effective zoning and land-use regulation. Here, the high-quality areas often match the standard of those in Europe and North America while the low-quality areas have no provision at all for piped water, sewers, drains, and paved roads.
There are also large contrasts in housing and environmental quality between different areas in most cities in Europe and North America. Many of their middle- and high-income areas (mostly but not all in the suburbs and beyond) have among the best-quality urban environments in the world. However, these same cities often have particular districts—most but not all in central areas—where the quality of the housing and the wider environment has deteriorated as local employment opportunities have declined and as the wealthier and more mobile people have moved out. The poorest areas in cities like New York and Glasgow have infant mortality rates several times higher than the wealthier areas of those cities, and average life expectancies that are many years lower. This problem is particularly acute in many of the cities that were the great centres of industry several decades ago, and which have been unable to attract new investment to reverse the rapid decline in industrial production and employment. It is also particularly acute in cities that are divided into different local government areas with little or no provision for a sharing of revenues or of city-wide costs between the richer and the poorer areas.
All cities have what might be termed a mosaic of high- and low-quality areas. Many of the high-quality areas are in the suburbs but the suburbs often have many low-quality areas too—especially in cities in Africa, Asia, and Latin America where much of the low-income population live in illegal or informal settlements that developed in certain suburban or peri-urban locations. Many of the low-quality areas may be in particular central-city areas but many cities still have central-city areas with high-quality living environments and high average per capita incomes. The quality of the environment in residential neighbourhoods can also change rapidly—for instance as the wealthier inhabitants of what had been a mainly middle-class inner suburb move out and cheap boarding houses develop there with many households coming to share the space and facilities that formerly served one household. Or as an inner-city area which had become a tenement district attracts higher-income households who renovate the building stock, increase the local tax base and bring pressure on the city authorities for improved services.
All urban environments represent a combination of individual and collective human efforts to make the natural environment more convenient for human activities—for instance, allowing the clustering of economic activities and the homes of the needed workforces. In virtually all urban centres, there are legal and institutional measures to reduce both natural and human-created environmental hazards within the urban boundaries. In most, there are also measures (usually set up and enforced by higher levels of government) to protect natural resources in their surroundings and to control pollution. In many, special measures are used to reduce risks from natural hazards such as storms, earthquakes, floods, or landslides (for instance, more stringent construction regulations for buildings in earthquake-prone areas). However, most urban environments show the limits of the law and the institutions of governance to achieve this. In many urban centres, lower-income groups live on land sites subject to flooding or landslides because it is too expensive for them to rent, buy, or build housing on safer sites. Lower-income groups also tend to live in the noisiest and most polluted areas. In some cases, industrial enterprises contravene laxly enforced environmental legislation.
IV CITIES AND THEIR SURROUNDS
All urban centres depend on natural resources drawn from beyond their boundaries and virtually all dispose of their liquid and solid wastes in their surrounds. Many also “export” air pollution—for instance as acid rain. Most draw fresh water from ground or surface sources outside their boundaries, with some needing to draw on freshwater resources from distant areas. Urban consumers and businesses also draw on the environmental resources of farmland, forests, and aquatic ecosystems beyond their boundaries. All these have environmental impacts on resources and ecosystems outside urban boundaries; the overall impact is often referred to as the urban centre’s “ecological footprint”.
Historically, virtually all urban centres had ecological footprints that were local, since the high cost of transporting food, fresh water, and other natural resources limited the area from which they drew. However, larger cities and wealthier consumers have enormously increased the volume of natural resources consumed by cities, while advances in transport and low fuel prices have allowed resources to be brought from ever-greater distances. The consumers and businesses in the world’s largest and wealthiest cities are using natural resources drawn from all over the world. Legislation has sought to reduce the environmental damage that urban wastes cause in their surrounding ecosystems, but this has often proved difficult as the environmental impacts take place outside the urban boundaries and the jurisdiction of the urban authorities. It is even more difficult to make urban populations feel responsible for the ecological problems to which they contribute when the resources they draw are from more distant ecosystems.
V SUSTAINABLE CITIES
Cities have an important part in achieving sustainable development—the meeting of human needs without a level of resource use and waste generation that threatens the local, regional, or global environment. Moving from a concern for the urban environment to a concern for sustainable development has resulted in a growing awareness of two new responsibilities of urban citizens and governments. The first is a concern for the environmental impact of urban-based production, consumption, and wastes on the needs of all people, not just those within the urban jurisdiction. The second is an understanding of the finite nature of many natural resources (or the ecosystems from which they are drawn) and of the capacities of ecosystems in the wider regional and international context to absorb or break down wastes. This means setting limits on the rights of city enterprises or consumers to use scarce resources and to generate non-biodegradable wastes. These wastes include greenhouse gases: global warming would bring many problems for urban centres—especially for the many major cities that are ports or on low-lying coastal areas—through sea-level rises and an increased instability of weather patterns.
Perhaps the most important implication of this global awareness for cities in the wealthier countries is the role of urban authorities in promoting the needed unlinking of high living standards from high levels of resource use and waste generation. Many cities have taken the first step, especially those that have developed their own “Local Agenda 21s” (modelled on the sustainable development plan produced at the Rio de Janeiro Earth Summit in 1992). As yet, however, support for these plans has rarely emerged at national levels of government.