Abstract
At the beginning of the nineteenth century, the total world population crossed the threshold of 1 billion people for the first time in the history of the homo sapiens sapiens. Since then, growth rates have been increasing exponentially, reaching staggeringly high peaks in the 20th century and slowing down a bit thereafter. Total world population reached 7 billion just after 2010 and is expected to count 9 billion by 2045. This paper first charts the differences in population growth between the world regions. Next, the mechanisms behind unprecedented population growth are explained and plausible scenarios for future developments are discussed. Crucial for the long term trend will be the rate of decline of the number of births per woman, called total fertility. Improvements in education, reproductive health and child survival will be needed to speed up the decline of total fertility, particularly in Africa. But in all scenarios, world population will continue to grow for some time due to population momentum. Finally, the paper outlines the debate about the consequences of the population explosion, involving poverty and food security, the impact on the natural environment, and migration flows.
Key words: Fertility, family planning, world population, population growth, demographic transition, urbanization, population momentum, population projections.
Keywords: Fertility, family planning, world population, population growth, demographic transition, urbanization, population momentum, population projections.
Introduction
In the year 1900, Belgium and the Philippines had more or less the same population, around 7 million people. By the year 2000, the population of the Western European monarchy had grown to 10 million citizens, while the South East Asian republic at the turn of the century already counted 76 million citizens. The population of Belgium has since then exceeded 11 million citizens, but it is unlikely that this number will rise to 12 million by the year 2050. The population of the Philippines on the other hand will continue to grow to a staggering 127 million citizens by 2050, according to the demographic projections of the United Nations (UN 2013).
The demographic growth rate of the Philippines around the turn of the century (2% a year) has already created enormous challenges and is clearly unsustainable in the long term: such growth implies a doubling of the population every 35 years as a consequence of which there would be 152 million people by 2035, 304 million by 2070, and so on. Nobody expects such a growth to actually occur. This contribution will discuss the more realistic scenarios for the future.
Even the rather modest Belgian demographic growth rate around the turn of this century (0.46%) is not sustainable in the long term. In any case, it exceeds by far the average growth rate of the human species (homo sapiens sapiens) that arose in Africa some 200.000 years ago. Today, earth is inhabited by some 7 billion people. To achieve this number in 200.000 years, the average yearly growth rate over this term should have been around 0.011% annually (so 11 extra human beings per 1.000 human beings already living on earth). The current Belgian growth rate would imply that our country would have grown to 7 billion in less than 1500 years.
The point of this story is that the current growth numbers are historically very exceptional and untenable in the long term. The demographic growth rates are indeed on the decline worldwide and this paper will attempt to explain some of the mechanisms behind that process. That doesn’t change the fact, however, that the growth remains extraordinarily high and the decline in some regions very slow. This is especially the case in Sub Saharan Africa. In absolute numbers, the world population will continue to grow anyway for quite some time as a result of demographic inertia. This too will be further clarified in this paper.
The evolution of the world population in numbers
