|An intersection in Tokyo, the biggest metropole in the world (7.3.2009).|
Only one thing is for sure: population growth cannot continue forever. At some point the population has to reach its peak. It may be interesting to evaluate or prophesy what the maximum figure will be, but I think there is one question that is more interesting or at least more important: how will this peak be reached? Will it be a bubble that bursts violently through a crisis initiated by a combination of ecological disasters, shortage of sustainable energy, ravaging famine and social problems or perhaps even something totally unprecedented, resulting in a dramatic decline in population? Or will the growth rate just steadily slow down to a point of stabilization? Of course there is also a third question that perhaps isn't really asked that often: will the anticipated peak be the permanent population maximum, or will it be superseded by a new peak after a temporary slump?
In any case, many people seem to think that the point of the (next) population peak will inevitably be a dramatic event. As of now, no-one really knows what it will be like, but the fact is that the relative population growth rate has already been declining for many years. As the standard of living and life expectancy increase, family sizes decline, which can be easily seen for example from the incredibly illustrative statistics service called Gapminder. The service shows each country plotted on a graph in a fashion that's essentially 4-dimensional, and you get to determine the variables for the axes yourself. For the same message you can alternatively check Hans Rosling, the man behind gapminder speak about population growth in the video below (If you don't want to check the entire video, you may want to skip straight to watch the minute from 7:00 to 8:00).
Contrary to Rosling's words, some might see him as an optimist. If he is, then I'm probably one too. Whatever challenges population growth may present, mankind has the ability to adapt. I believe the population peak won't be reached before the round figure of 10 billion people, but when it will, it may very well be an undramatic event.