Demographic Change

Population Size and Growth

World population grew very slowly for many thousands of years. It is thought to have reached 8 million by 8000 BCE, and by 1800 it stood at around 1 billion. Since then, population has soared, reaching 2 billion in 1927, 4 billion in 1974, and nearly 7 billion in 2010. The UNPD projects that it will reach more than 9 billion by 2050. The annual growth rate of world population has risen and fallen dramatically over time. In the early 1950s, the rate was 1.8% per year. After rising to 2.0% per year in the late 1960s, it fell to 1.1% in 2010 and is projected to be 0.3% by mid-century.

Population growth rates have varied greatly by level of development and specific region of the world (see Table 1, which shows population growth rates in specific years). As currently categorized by the UNPD, “less developed regions” have long been growing much faster than “more developed regions.” The former, which accounted for 68% of world population in 1950, represented 82% in 2010 and are projected to constitute 86% by 2050. Nearly all of the 2.2 billion population increase projected to occur between 2010 and 2050 will take place in the less developed regions, and more than one third of that will take place in what the United Nations refers to as the “least developed countries,” which tend to be the economically, socially, environmentally, and politically most fragile countries of the world.

A large part of the increase in the share of world population that lives in less developed regions is attributable to population growth in Africa, which constituted 9% of world population in 1950 but is projected to make up 22% in 2050. The most rapid period of growth in Africa was the early 1980s, when the annual rate reached nearly 2.9%. Asia also grew rapidly, reaching an annual growth rate of 2.4% in the late 1960s, but its growth rate fell quickly thereafter and is projected to be nearly as low as that of the developed world by 2050. Latin America reached its peak, nearly 2.8%, in the early 1960s, but population growth there slowed even more rapidly than in Asia.

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