United Nations, Apr 6 (IANS): The 2011 version of a UN report on urbanization has projected that there will be significant increases in population in cities on the Asian and African continents by the year 2050, an official said here.

"Africa's urban population is expected to more than triple from 414 million to 1.26 billion people and Asia's urban population will increase by an estimated 1.4 billion from 1.9 to 3.3 billion," Jomo Kwame Sundaram, UN assistant secretary-general for economic development in the Department of Economic and Social Affairs (DESA), told reporters Thursday.

The announcements came at a press conference to launch the 2011 Revision of the World Urbanization Prospects. Every two years since 1988, the population division of DESA has released estimates of population changes around the world, reported Xinhua.

"Globally, as you know, urban areas are expected to absorb all future population growth," said Sundaram.

"Between 2011 and 2050, the world population is expected to increase by 2.3 billion. Global urban population will increase by 2.6 billion."

He said there are projected to be "significant disparities" between urban population growth in different regions. Africa and Asia will lead the way, according to the report, accounting for 86 percent of global urban population growth.

"However, the urban population in Europe is expected to grow by only about 52 million and in North America by about 110 million and in Latin America and the Caribbean by about 178 million," Sundaram said.

The report indicated that by country, the greatest increases in urban population are expected in India, China, Nigeria, the US and Indonesia. India and China will add the most people, a projected 497 million and 341 million people, respectively, to cities.

Sundaram emphasized the new challenges that increased urbanization will bring.

"Africa and Asia will have to experience very significant economic growth to be able to increase urban employment opportunities, expand urban transportation and infrastructure, improve water supply systems as well as energy systems," he said. "These urban areas will also need significant expansion in terms of housing as well as public health services and school systems."

He also cited the exposure of many cities to natural hazards as a challenge for the future.

"Sixty percent of all cities with one million or more inhabitants will be located in areas with at least one major risk of natural disaster, earthquakes or flooding," he said.

Sundaram explained that a need to focus on the challenges posed by growing urbanization will make the discussions surrounding the upcoming UN Conference on Sustainable Development (Rio+20) all the more important.

"Cities are precisely where the pressures of migration, globalization, economic development, social inequality, environmental pollution, and climate change all come together," he said.

High-level representatives from all over the world will gather in Rio de Janeiro, Brazil June 20-22 for Rio+20, where they will discuss sustainable development progress globally and chart a course for the future. One of the conference's themes will be sustainable cities.