COLUMBIA EARTH INSTITUTE
Somewhere around the end of the 20th century the world’s human population reached 6 billion. At least, it probably did. There are many countries where no population census is taken at all and others where a census is taken but the results are not made public. Even in the US and other sophisticated countries, estimates of population are good to no better than 2% or so. Still, within the next few years the world’s population will certainly exceed 6 billion, if it hasn’t already. The best present estimate is 6.1 billion with an uncertainty of a quarter of a billion. That is, the uncertainty in the estimate of the world’s human population is about the size of the population of the United States. Nevertheless, the date on which the world reached 6 billion human inhabitants was “predicted”. It might be better to say that it was announced because there is no way of verifying whether the prediction was true. For that matter, there is no value at all, no real point in making such a prediction other that as a way of raising awareness about the growth of population in the 20th century. It did achieve that point.
Joel Cohen, of Rockefeller University and Columbia’s Earth Institute has pointed out many curious and some alarming derivative facts that underlie this simple number. For instance, it took from the dawn of time until about 1830 for the Earth to acquire its first billion people. It took only 12 years for the Earth to acquire its last billion people. Every one who is more than 39 years old has seen the population of the world double. Anybody born before 1930 has seen the population triple. And the rate of population growth has, until very recently, steadily increased. Put another way, the doubling rate has steadily decreased. As Cohen puts it, that’s like a bank account in which the interest rate keeps increasing the more money you have in the bank. The growth rate is much steeper than exponential. Nobody predicted it.
Had it been predicted, would we have been able to anticipate that of the 6 billion people on the planet fully half would exist on less than $2 a day and that perhaps 2 billion exist on less than $1 a day? Yes, costs and standards of living and expectations differ in different parts of the world, but no matter how one looks at it, almost a third of the world’s population is “poor” by any reasonable definition.
There are, in fact, two worlds – the world of the rich and the world of the poor. In the poor world a child is seven times more likely to die before the age of 12 months. That child will have 2 siblings on average, while in the rich world a child has 0.6 siblings. In the poor world you probably don’t have anywhere to go to the toilet. If you are an adult woman you are probably illiterate. In the rich world you are more likely to live in an urban area and in a square kilometer around you there will be about 20 other people. In the poor you probably live in a rural area and despite that, in the a one kilometer square around you there are about 60. Of the 60 people in the poor persons square kilometer 20 or so are chronically hungry. They will wake up hungry, spend the day hungry and go to sleep hungry, only to wake and repeat the cycle day in and day out until they die at around the age of 25. Had we scientists been able to predict that the population would rise to 6 billion, would we have been able to anticipate and mitigate the miseries of the poor world of which I have noted only a very few?
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