Urbanization causes environmental and economic strain on land and people. Additionally, urbanization can indirectly affect society by contributing to health problems as a result of pollution and food shortages.
More than half of the world's population lives in an urban setting. Many people relocate to cities from rural areas in search of better job opportunities and access to services, such as health care and education. However, a higher concentration of people within a region can cause shortages of important resources, such as food and water. Stores of petroleum and natural gas, as well as ecosystems destroyed by massive deforestation to accommodate growing populations, cannot be immediately replaced. Increased industrial activity also raises pollution levels that contribute to respiratory health problems. A lack of appropriate sanitation and waste disposal systems increases the spread of infectious disease.
Urban communities must devise plans to contain health care costs while investing in hospitals and clinics at the same time. Preventative measures, such as environmentally friendly public transportation, can also be costly.
Urban areas may also undergo gentrification, a process in which wealthy young professionals relocate to once economically depressed areas. As the economic demographics in the area shift, the cost of living in the area rises and displaces the original inhabitants, often minorities whose culture significantly contributed to the character of the area.