Cities are growing at a rate of around 1 million people every week. Half the Earth's population will soon live in congested, urban regions mainly in the poor, developing countries of Asia and Africa. If the 20th century was the century of urban sprawl, the 21st century will be the century of the megacity. A megacity is defined as a city with an estimated population of more than 10 million people. The 10 largest megacities in the world …showed first 75 words of 255 total…

…showed last 75 words of 255 total…region in theworld. The world's megacities take up just 2 percent of the Earth's land surface, yet they account for roughly 75 percent of industrial wood use, 60 percent of human water use, and nearly 80 percent of all human produced carbon emissions. Between 1990 and 2025, the number of people living in urban areas is projected to double to more than 5 billion- 90 percent of that increase will occur in developing countries. The explosion and growth of megacities worldwide is unprecedented.