Despite that figure, there is a finite amount of water useable by humans and it is constantly used and reused in a sustainable water cycle.
One demand of the population boom on the planet is an attendant requirement for more food to be produced. If more men move to towns and cities than women, this leaves a predominantly female society in rural areas.
The share of the urban population living in slums by country is shown in the chart below. What factors lead to a sex ratio in which men outnumber women?
Higher-income countries, particularly across Europe, North America and Australasia already had large urban populations in the midth century. Functional perspectives on urbanization focus generally on the ecology of the city, while conflict perspective tends to focus on political economy.
Brown zones where nothing can grow are common results of soil pollution.
This illustration depicts the concentric zones that make up a city. Sometimes the wastes are collected and taken to legalised waste disposal sites but these are not always properly managed to protect water bodies and groundwater.
The increased density of populations in urban areas led to the rapid spread of infectious diseases. In the chart below we show the percentage of the total population which live in agglomerations greater than one million people i.
In several provinces, there are product stewardship programs that oblige manufacturers and retailers to pay a per-item fee to fund electronic recycling Fishlockbut it is not always clear what happens to the items after they are recycled.