According to the UN Department of Economic and Social Affairs Population Division 2004 Revision of the official UN population estimates and projections, released 24th February 2005, world population is expected to increase by 2.6 billion over the next 45 years, from 6.5 billion to 9.1 billion in 2050. Nearly all this growth will take place in less developed regions, where the population of 5.3 billion is expected to reach 7.8 billion. The population of the more developed regions will remain largely unchanged, at 1.2 billion.

Population

By July 2005, world population will be 6.5 billion, 380 million more than in 2000, an increase of 76 million annually. Despite projected lower fertility levels, by 2050 world population will still be increasing by 34 million annually.

Because of low and declining rates of population growth, the population of most developed countries is expected to remain virtually unchanged, but the population of the 50 least developed countries is projected to more than double from 0.8 billion in 2005 to 1.7 billion in 2050, with some of them experiencing a tripling of population.

The population of 51 countries or areas, including Germany, Italy, Japan and most of the former Soviet Union states, is expected to be lower in 2050 than in 2005.

Eight countries are expected to account for half of the world's projected population increase: India, Pakistan, Nigeria, Democratic Republic of the Congo, Bangladesh, Uganda, United States of America, Ethiopia, and China, listed according to the size of their contribution to population growth.

Fertility

In 2000-2005, world fertility averaged 2.65 children per woman. This is projected to decline to 2.05 children per woman. In developed countries as a whole, fertility is currently 1.56 and is projected to increase to 1.84 in 2045-2050. In the least developed countries, fertility is 5 and is expected to drop to 2.57 by 2045-2050. In the rest of the developing world, fertility is 2.58 and is expected to decline to 1.92 by mid-century. However, fertility has reached below-replacement levels in 23 developing countries accounting for 25 per cent of the world population. This group includes China, whose fertility during 2000-2005 is estimated at 1.7 children per woman.

Life expectancy

Global life expectancy at birth is estimated at 65 years in 2000-2005, and is expected to reach 75 years in 2045-2050. In more developed regions, the projected increase is from 75 years today to 82 years by mid-century. Among least developed countries, life expectancy is just under 50 years, and it is expected to be 66 years in 2045-2050. However, many of these countries are highly affected by the HIV/AIDS epidemic and projected increase in life expectancy is dependent on the implementation of effective programs to prevent and treat HIV infection.

Aging

Globally, the number of persons aged 60 years or over is expected almost to triple, increasing from 672 million in 2005 to nearly 1.9 billion by 2050. In developed countries, 20% of today's population is aged 60 years or over, and by 2050 that proportion is projected to be 32 per cent.

Migration

During 2005-2050, the net number of international migrants to more developed regions is projected to be 98 million. Because deaths are projected to exceed births in the more developed regions by 73 million during 2005-2050, population growth in those regions will largely be due to international migration.

More details of the revision can be found at http://www.un.org/esa/population/unpop.htm