Six billion and counting: it took all of recorded history until 1804 for world population to reach one billion; it took another 123 years to reach two billion; by 1960, it hit three billion; 1975, four billion; 1986, five billion; and, in 1999, we crossed the six billion mark.

In 1900, the world's population was growing at about 10 million people a year. At the beginning of the 21st century, it was growing at just under 80 million a year (it peaked in the late 1990s at 82 million). As one writer calculated, even if we were distributed evenly across the planet's 60 million square kilometres of habitable land, we would still be within easy calling distance of our neighbours: we would be only about 100 metres from each other.

During the 1960s, it dawned on a lot of people that the world might be heading for a population catastrophe. In his 1968 book, The Population Bomb, biologist Paul Ehrlich predicted imminent disaster caused by overpopulation in the form of mass famine and economic catastrophe. The author wrote that "a minimum of ten million people, most of them children, will starve to death during each year of the 1970s. But this is a mere handful compared to the numbers that will be starving before the end of the century." It turns out Mr. Ehrlich was being a little hysterical, failing to predict, for example, the advances that would be made in agriculture. As one critic pointed out in 1995, "Food production not only increased, but increased faster than population growth, so 27 years after the publication of The Population Bomb, not only are there many more people alive in the world, but they eat more than they did in the past. Water quality, which Ehrlich believed beyond repair, has also steadily improved."

But, while the future wasn't as grim as Paul Ehrlich suggested, the need to curb population growth was self-evident. In 1950, there were 2.5 billion people in the world. Since 1960, the world's population has more than doubled from three billion to about 6.4 billion today. We are growing by about 76 million people a year. By 2050, there will be more than nine billion of us, and nearly nine of every 10 people will live in a developing country.

Most of the world's growth in the last five decades has been in the poorest countries, and that is expected to continue. India's population, for example, will grow 52 percent to 1.6 billion by 2050, when it will overtake China to become the world's most populous country. Together, China and India account for more than a third of the world's population.

The Population Reference Bureau (PRB), a private U.S. research group, predicts that Africa could have a billion more people by 2050, more than doubling the current figure to 1.9 billion. Such an increase will be hard on countries that already are struggling to provide basic necessities such as food and water. At the same time, a United Nations study calculated that, even though AIDS will kill hundreds of millions in Africa, the number of people in the world's 48 poorest nations, mostly in sub-Saharan Africa, is expected to triple in the next half century.

According to the PRB, the population in industrialized countries will increase by only four percent by 2050, compared with 55 percent in developing countries. So, while Western European populations, for example, will shrink, Western Asian nations will gain about 186 million people by mid-century.

In 1950, about 32 percent of the world's population lived in Europe, North America, and Japan. By the late 1990s, 20 percent did, and in 2050 the figure will be about 12 percent.

Some progress is being made. After a peak by mid-century, the numbers are expected to start declining. By 1997, 51 countries were on the list of nations whose fertility rates (average number of children born to women during their childbearing years) were 2.1 or lower. That 2.1 figure is the population replacement rate and experts say countries around the world should aim to drop below it. Four years later, in 2001, 83 countries were thought to have below-replacement fertility. Low fertility rates exist mostly in wealthy, industrialized countries. But, women in some poor countries are producing far fewer babies as well. Countries such as Thailand, Bangladesh, and Kenya, where women used to have an average of six or more children, have seen the number cut in half.

In developed countries such as Japan and many European nations population decline is already underway. Southern Africa, East and Southeast Asia, Latin America, the Caribbean, and the South Pacific are at or close to the stabilization point.

But, the problem of overpopulation is far from over. For countries with large populations even small growth rates add up to large numbers: a one percent increase in China's population, for example, still means 13 million more people.

As the United Nations Population Fund (UNFPA) sees it, rapid population growth puts added pressure on the environment and natural resources, impedes development, and reduces the quality of life for everyone. The UN says "global warming, deforestation, growing scarcity of water and diminishing crop land will make it harder to address poverty and gender inequality."

Many experts are nodding in agreement. The Population Institute, based in Washington, D.C., is an international, educational, non-profit organization that aims to reduce population growth. The Institute points out the many problems that accompany an overcrowded earth. Here are some of them:

* One billion people lack access to any form of health care;

* At least 220 million people in the developing world lack clean drinking water, 600 million do not have adequate shelter, 840 million are malnourished, and 1.1 billion are subject to high levels of air pollution;

* At least five million children die each year from waterborne diarrheal diseases due to a lack of proper sanitation and clean water;

* Nearly three billion people, half of the world's population, subsist on less than $2 per day and the number and proportion are rising;

* Worldwide unemployment affects one billion people, nearly one-third of the global workforce;

* The number of rural women living in poverty in developing countries has increased by almost 50 percent over the last 20 years, to 565 million;

* One-and-a-half million square kilometres of forest were cut down in the last decade;

* Twenty-six billion tonnes of arable topsoil vanish from the world's cropland every year;

* In less than 50 years, population growth will contribute to a near doubling of food requirements;

* Global warming has increased by 25 percent since World War II; and,

* As many as 2.7 billion people, almost one-half of the world's population, will live in regions facing severe water scarcity by 2025.

SUGGESTED ACTIVITIES:

1. Paul Ehrlich, in his book The Population Bomb, expressed the opinion that Third World nations would never achieve "self-sufficiency" in feeding their populations. Complaining about "the assorted do-gooders who are deeply involved in the apparatus of international food charity," Mr. Ehrlich agreed with those who believed the world should simply stop both private and government-sponsored food aid to nations that experience chronic food shortages. Discuss this view.

2. Doomsayers such as Thomas Malthus (see page 7) and Paul Ehrlich often base their predictions on faulty thinking because they're unable to account for future events that counter their dire prophecies. Discuss positive possibilities that you think might help the world toward a better future.

FACT FILE

From 1950 to 1955 the global total fertility rate was five; from 1975 to 1980 it was four; and 15 years later it fell to just below three.

The world's total population will grow by about 720 million people (more than 20 times Canada's population) in each of the next two decades, and most of the increase (95 percent) will occur in poor countries.

The living population of the world forms about nine percent of the total number of humans who have ever lived.

The World's 10 Largest Countries

Worlds Largest Countries, 2004

Rank   Country               Population (millions)

1      China                                 1,300
2      India                                 1,087
3      United States                           294
4      Indonesia                               219
5      Brazil                                  179
6      Pakistan                                159
7      Russia                                  144
8      Bangladesh                              141
9      Nigeria                                 137
10     Japan                                   128

World's Largest Countries, 2050

Rank   Country               Population (millions)

1      India                                 1,628
2      China                                 1,437
3      United States                           420
4      Indonesia                               308
5      Nigeria                                 307
6      Pakistan                                295
7      Bangladesh                              280
8      Brazil                                  221
9      Congo, Dem. Rep. of                     181
10     Ethiopia                                173

Source: Population Reference Bureau

Websites

Population Connection (formerly Zero Population Growth)--http:// www.populationconnection.org

The Population Institute--http:// www.populationinstitute.org/

Population Reference Bureau--http://www.prb.org