Would you rather see our population decrease or our standard of living?

World Population Day

July 11th is World Population Day. This year Thoraya Ahmed Obaid, Executive Director of the United Nations Population Fund (UNFPA), said in a statement to mark the occasion, "Today on World Population Day, let us recommit ourselves to this vision of a better world. Let us commit ourselves to equality, justice and human rights for all."

According to the CIA, the world population is around 6,446,131,400.

World Population 10,000 BC to 2050 AD

World Population 1700 AD to 2050 AD

Estimates vary, but the population of the entire world is believed to have been between 1 and ten million in the year 10,000 BC, around the time that farming began, reaching about ten times that number in 500BC, around the time of Confucius. It doubled in the 1100 years to 600 AD (around the time of Mohammed) then again in only 650 years to 1250, around the time of Kublai Khan. The next doubling was around 1800 (Thomas Jefferson was elected president) and it had doubled again soon after 1900 (Wright brothers' flight) and again around 1963 (J F Kennedy assassinated) and it has just doubled again. The first chart shows what a meteoric rise in population there has been, and that is projected for the next 45 years. The world population in 1999 was ten times that of 1700, around the time that Detroit was founded. The second chart shows the period since the start of the Industrial Revolution more clearly. The population may peak at about 9 billion (about half as many again as there are now) around the year 2050.

All these people need places to live, to shop, and often places to work. They need places where there food is grown or raised, and often roads, hospitals and other facilities. They need places where their belongings are made; places where their fuel comes from, and raw materials are mined. All this space when added up is known as an ecological footprint, which for citizens of developed countries like the USA is much larger than the land they own or rent to live on. There is a limit to how much food, water, fuel, clean air, and land to live on that the Earth can provide us with, even if we improve efficiency of food production and transport.

The amount of pollution in the world is also affected by the world population, for example each person needs fuel for warmth, cooking and transport plus production of food and clothes etc., and perhaps fertilizers and pesticides as well. Not all people contribute the same amount of pollution though, as it also depends on lifestyle. Some parts of the world are more crowded than others (see map of population density, 1995).

Environmentalists use the equation below fairly often, where the resource could be energy or water or land or air, for example:

Environmental Impact (I) = Population (P) x Resource use per head (R) x Technology used (T)

It shows that we can reduce mankind's environmental impact by reducing our population, cutting down on the resources that each us use, or by changing the technology that we use to less harmful forms (less polluting power plants or vehicles, for example).

Human populations can crash, just like animal ones, and this happened as a result of the Black Death (bubonic plague) during the 14th century. It has happened to a lesser extent (percentage wise) as a result of flu pandemics (the 1918 Spanish flu pandemic killed 50m). Because such disease can be carried by migratory birds, and we can ourselves carry them by flying now (as the SARS breakout showed), there is a real possibility of a major pandemic reducing our numbers. Terrible though this would be, it would not be the end of the world - the bubonic plague was followed by the Renaissance, for example. Another way of reducing the population is through war, which becomes more and more likely the more crowded we are and the more competition there is for limited resources.

Some creatures have high birth rates, producing large numbers of young ready to look after themselves, but very few survive to adulthood. Others, like Giant Pandas, have far fewer offspring but take good care of them for a relatively long time. We humans have a relatively low birth rate, which makes it all the more amazing that our numbers have grown in the way that they have.

Population is a function of both birth rate and death rate. In the west, we have overcome many illnesses and birth conditions that used to kill many of us, reducing our death rate. Birth rates in many western nations have slowed (where native-born populations are in some cases shrinking), and also in China due to a one child law. Birth rates in places like India have skyrocketed, however. This variation does show that we are able to modify our own numbers if we really want.

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