With world population day (11 July) this week lets take a deeper look at earth’s human population.
When talking about the world population people often refer to three rates: the fertility rate, the birth rate and the death rate. The fertility rate is a bit of a misnomer as it has very little to do with human fertility or the ability to reproduce. The fertility rate indicates the average amount of people born per person with a uterus per lifetime; no actual counting is involved. The birth rate records the number of people born (only live births) per 1000 people currently alive, while the death rate gives the amount of people who stop living per 1000 people still alive. For the human population to stay the same the amount of people who start living (are born) must equal the amount of people who stop living (die). This year thus far over 76 000 people were born and almost 32 000 have died, that means the human population has increased by 44 000 people.
For a country’s population to stabilise both the natural increase (births – deaths) and migration should be taken into consideration. Countries who currently experience a natural decrease (more people die than are born) should not propagate procreation but rather migration to fill the gap.
Many people are under the impression that if the fertility rate equals 2 or 2,1 (to account for child mortality) that the human population will stabilise. It was often propagated to the baby boomers that they should only have two children to replace themselves thus the term the replacement rate. However, people are not mayflies – we do not die after we reproduce so we are not replacing ourselves, but we might be replacing our grandparents.
Currently in 2015/2016 there are about 2 Billion children in the world (ages 0 to 15), despite a decreasing fertility rate (2,47 in 2015 to 2,18 in 2060) it is expected that this number will stay the same from now at least until 2060 when we reach 10 Billion people. As there are more people who have less children the amount of children stay the same. Just 60 years ago in the late 1950s there were only 1 Billion children on earth, and the fertility rate, then 5, has halved since as both the child and overall population doubled. This Ted Talk by Hans Rosling shows what happens to the population when 2 Billion people are added at the beginning, while there isn’t two billion who leave at the end.
If you are in your late twenties now, thus born between 1986 and 1990, think about the following: When you were born there was approximately 5 Billion people on earth, if you live to the average expected age of 73 to 75 the world population will have doubled in your lifetime reaching 10 Billion. Currently the world population is growing by 1% which will decrease to 0,5% by 2060, but 1% of 7 Billion is a lot and so is 0,5% of 10 Billion.
Is 10 Billion humans a lot for the earth? The range of research on the subject reveals the human carrying capacity, the amount of people the earth can support while supporting other species too, could be anywhere between 2 Billion and 10 Billion. The amount of people the earth can support depends in part on our ability to support ourselves, and also
the living standards we set for ourselves. If we have the technology to use earth’s resources more effectively (get the most out of it) and sustainably (without destroying its capacity to provide in future) there can be more of us. If we want to consume like the average European, or even more like the average American, there will have to be less of us.
For a fine explanation of why it is in the interest of all of us to help developing countries out of poverty to reduce population growth see this Ted Talk by Hans Rosling.
All data acquired from: United Nations, Department of Economic and Social Affairs, Population Division (2015). World Population Prospects: The 2015 Revision, custom data acquired via website.