Cities have existed for thousands of years and can be traced back to the river valley civilizations of Mesopotamia (present-day Iraq), Egypt, India, and China. At first, these settlements depended largely on agriculture and domestic cattle, but as they grew in size they became centers for merchants and traders.
Urban growth, also known as urbanization, accelerated dramatically with the advent of industrialization some 200 years ago. At that time, large numbers of people moved to cities in search of jobs, mostly in factories. But the most rapid growth has taken place over the past 50 years. While less than one-third of the world's population lived in cities in 1950, about two thirds of humanity is expected to live in urban areas by 2030. Most of that urbanization is taking place in Asia, Africa, and Latin America.
Urban is defined as "that which is characteristic of a city." But what exactly is a city? In the past, walls may have defined a city. But today's city boundaries are often blurred. Are suburbs, which are often called metropolitan areas, part of cities? Depending on the boundaries used, Tokyo can have a population of anywhere between 8 and 40 million people.
Cities make a lot of sense for humans. People are concentrated in a small space rather than being spread out over a large territory. This allows the government and others to provide more service such as water, electricity, and transportation to a larger number of people. Schools and shops are more easily accessible than in rural areas.
Cities have always been at the center of economic growth and technological advances. The promise of jobs and prosperity pulls people to cities. But their rapid growth has also brought with it many negative things: violence, poverty, overcrowding, health problems, and pollution. Many cities in developing countries in particular are growing too rapidly for their own good, with many residents unable to find jobs and forced to live in slums.
Urban expansion is also encroaching on wildlife habitats everywhere. Increasingly people live and work in close proximity to wild animals whose native habitats have been lost or broken up. Many animals—from mice and cockroaches to pigeons and squirrels—have adapted to city life, taking advantage of abundant food and warmer temperatures.
(SOURCE : http://environment.nationalgeographic.com/environment/habitats/urban-profile/)
(SOURCE : http://environment.nationalgeographic.com/environment/habitats/urban-profile/)
Urban Threats
The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.
The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.
Poor air and water quality, insufficient water availability, waste-disposal problems, and high energy consumption are exacerbated by the increasing population density and demands of urban environments. Strong city planning will be essential in managing these and other difficulties as the world's urban areas swell.
Threats
- Intensive urban growth can lead to greater poverty, with local governments unable to provide services for all people.
- Concentrated energy use leads to greater air pollution with significant impact on human health.
- Automobile exhaust produces elevated lead levels in urban air.
- Large volumes of uncollected waste create multiple health hazards.
- Urban development can magnify the risk of environmental hazards such as flash flooding.
- Pollution and physical barriers to root growth promote loss of urban tree cover.
- Animal populations are inhibited by toxic substances, vehicles, and the loss of habitat and food sources.
Solutions
- Combat poverty by promoting economic development and job creation.
- Involve local community in local government.
- Reduce air pollution by upgrading energy use and alternative transport systems.
- Create private-public partnerships to provide services such as waste disposal and housing.
- Plant trees and incorporate the care of city green spaces as a key element in urban planning.
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