( dpa ) - Half of the world's 6.7 billion people are expected to live in urban areas by the end of 2008 for the first time in world history, the United Nations said Tuesday.
The world population is expected to increase by 2.5 billion by 2050, to 9.2 billion. By that time, urban population is expected to rise from nearly 3.4 billion in 2008 to 6.4 billion in 2050.
The urban regions thus will absorb most of the world's population increase in the next four decades while drawing on some of the rural population as well. There will be 600 million fewer inhabitants in rural areas by 2050, the report said.
The projected urban population figure of 6.4 billion dollars represented a drop from last year's anticipation of 8.4 billion people in urban areas because experts believe the birth rates will decline more rapidly than they originally thought.
The population department of the UN Economic and Social Affairs, which studies trends and provides governments with data as a basis for policy, provided the revisions on Tuesday.
"In many countries, natural increase of population (births minus deaths) accounts for 60 per cent or more of urban population growth," the department said in the report, called the 2007 Revision of World Urbanization Prospects.
The report said that countries with policies that "facilitate the reduction of fertility by making it possible for couples to have the number of children they desire" can actually help stabilize urban growth.
As with the general population growth, most of urban increases will take place in developing and less developed countries as opposed to developed nations, in which 74 per cent of population already live in big cities and towns.
By 2050, 54 per cent of population in Asia and 19 per cent in Africa will live in cities. Africa and Asia still have large rural populations, but not Latin America and the Caribbean, where 78 per cent of the population already lives in cities.
The Tokyo metropolis, currently with 35.7 million people, will continue to dominate the group of 19 metropolises up to the year 2025 and beyond in terms of population size.
In 2007, the top 10 biggest agglomerations were Tokyo, New York/Newark, Mexico City, Mumbai, Sao Paulo, Delhi, Shanghai, Calcutta, Dhaka and Buenos Aires.
In 2025, the top 10 are projected to be Tokyo, Mumbai, Delhi, Dhaka, Sao Paulo, Mexico City, New York/Newark, Calcutta, Shanghai. Karachi and Kinshasa could be tied for tenth largest.