In July 2007 the world population will reach 6.7 billion, 547 million more than in year 2000 or again of 70 million persons annually.
The 2006 Revision of official United Nations population estimates, projections prepared by Population Division of UN Secretariat key findings say assuming that fertility levels continue to decline, world population is expected to reach 9.2 billion in 2050 and increasing by about 30 million persons annually at that time.
Future population growth is highly dependent on path that future fertility takes. In medium variant, fertility of the world declines from 2.55 children per woman today to slightly over 2 children per woman in 2050.
If fertility were to remain about half a child above levels projected in medium variant, world population would reach 10.8 billion by 2050. A fertility path half a child below medium variant would lead to population of 7.8 billion by mid-century. That is, at world level, continued population growth until 2050 is inevitable even if decline of fertility accelerates.
Due to its low, declining rate of population growth, population of developed states as a whole is expected to remain virtually unchanged between 2007 and 2050, at about 1.2 billion.
In contrast, population of 50 least developed states will likely more than double, passing from 0.8 billion in 2007 to 1.7 billion in 2050. Growth in rest of developing world is also projected to be robust, though less rapid, with its population rising from 4.6 billion to 6.2 billion between 2007 and 2050 according to medium variant.
Slow population growth brought about by reductions in fertility leadstop population ageing, that is, it produces populations where proportion of older persons increases while that of younger persons decreases. In more developed regions, 20 percent of population is already aged 60 years or over and that proportion is projected to reach 33 percent in 2050.
In developed states as a whole, number of older persons already surpassed number of children (persons under age 15) and by 2050 there will be more than twice as many older persons in developed countries than children.
Population ageing is less advanced in developing states and populations of a majority of them are posed to enter a period of rapid population ageing. In developing countries as a whole, just 8 percent of population is today aged 60 years or over but by 2050, 20 percent of their population is expected to be in that age range.
Although population of all countries is expected to age over foreseeable future, it will remain relatively young in stats where fertility is still high, many of which are experiencing very rapid population growth. High population growth rates prevail in a number of developing states, majority of which are least developed.
Population growth remains concentrated in populous stats. During 2005-2050, eight countries are expected to account for half of the world's projected population increase: India, Nigeria, Pakistan, Democratic Republic of Congo, Ethiopia, United States, Bangladesh & China, according to 2006 UN Revision.
Median age, that divides population in two halves of equal size, can be used as an indicator of population ageing. At world level, median age is projected to increase from 28 to 38 years between 2005 and 2050. Europe has today oldest population, with a median age of nearly 39 years, which is expected to reach 47 years in 2050.
The median age is higher in countries that have been experiencing low fertility for a long time. In 2005, 13 developed states or areas had a median age higher than 40 years. The expected pervasiveness of population ageing is reflected by fact that in 2050, 93 countries are projected to have median ages above 40 years, 48 of which are developing.