The life cycle of a plastic bag
- 5 trillion bags are produced each year -
image:http://sustainablecitiescollective.com/60906/life-cycle-plastic-bag
Problems caused by urban development
A city system is made up of a number human and natural sub-system. These systems support urban activities by providing resources from the natural environment. People use these resources to produce goods and services. However, cities also produce waste at the same time, such as sewage, rubbish and air pollutants. As the natural environment is self-regulating (this means it is able to adjust itself in order to maintain a balance), the whole city system will, in general, keep on functioning in a normal way. However, if human activities exceed the carrying capacity of the natural system, the environment will begin to deference.
image:http://sustainablecitiescollective.com/60906/life-cycle-plastic-bag
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