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GEO-3: GLOBAL ENVIRONMENT OUTLOOK  
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The changing population

World population (millions) by region, 1972-2000

World population is currently growing at 77 million a year, with two-thirds of the growth in Asia and the Pacific

Source: compiled from United Nations Population Division 2001

World population increased from about 3.85 billion people in 1972 to 6.1 billion in mid-2000 (see figure right), and is currently growing by 77 million people a year (UNFPA 2001). Most of the growth is concentrated in developing regions, with nearly two-thirds in Asia and the Pacific. Six countries accounted for 50 per cent of the annual growth: India (1 per cent), China (2 per cent), Pakistan (5 per cent), Nigeria and Bangladesh (4 per cent each) and Indonesia (3 per cent) (United Nations Population Division 2001).

The population of industrialized regions, currently 1.2 billion, is expected to change little in the next 50 years while that of the developing regions is projected to increase from 4.9 billion in 2000 to 8.1 billion by 2050 (United Nations Population Division 2001). This difference is mainly due to levels of fertility. Less developed countries recorded fertility at 3.1 children per woman over the period 1995-2000, while developed countries recorded fertility at 1.57 children per woman over the same period - well below the replacement level of 2.1 children per woman (UNFPA 2001).

The gap in life expectancy between the developing and the more developed regions narrowed from 22 years in 1960 to less than 12 in 2000. Between 1995 and 2000, life expectancy in the industrialized regions was estimated to be 75 years, compared to about 63 years in developing regions (United Nations Population Division 2001). As world fertility continues to decline and life expectancy rises, the population of the world will age faster in the next 50 years than during the past half-century (United Nations Population Division 2001). Nevertheless, the emergence of HIV/AIDS in the 1970s has depressed life expectancy in the most affected countries, and the disease is now the fourth most common cause of death worldwide. More than 60 million people have been infected with HIV since the 1970s, and 20 million have died. Of the 40 million living with HIV/AIDS worldwide, 70 per cent are in sub-Saharan Africa where it is the leading cause of death (UNAIDS 2001). Compared to Africa, the relative impact of the HIV/AIDS epidemic in most other regions of the world is still low.

There have been notable population movements over the past 30 years due to rapid urbanization, international migration and the movement of refugees and displaced persons. The number of people living outside their own countries rose from 84 million in 1975 to an estimated 150 million people at the end of the 20th century (UNDP 1999, UNHCR 2000). The number of refugees rose from 2.7 million in 1972 to a peak of 18.3 million in 1992, and stood at 11.7 million at the end of 1999 (UNHCR 2000). By 2001, an estimated 22 million people 'of concern' were numbered among the world's refugees, returnees and persons displaced within their own countries (UNHCR 2001). The more developed regions are expected to continue being net receivers of international migrants, with an average gain of about two million a year over the next 50 years. Because of low fertility in recipient countries, this migration will have a significant impact on population growth in the developed regions (United Nations Population Division 2001).