But parents donít die when they have children so when you have 2 parents with 2 children you are not at 0 you have 100% increase. The point is not that we will decrease number with time the point is that we are spending more then it can be produced/ regenerated and we are destroying the system by our actions.
In about 2 years from now there will be 7 billion people on this planet. So letís say that in the next 10 years billion women and billion man will have children. If they have only one child we will have another billion and there is no way that everybody will have just one. Of course old and smaller generations die but world still has a strong surplus.
In a case that we get 1.5 billion of new people and about 0.5 billion dies as old (generation is smaller) we will get an extra billion.
One billion divided in 10(years) = 100 000 000 extra every year. Divide that with 365 and you get about 270 000 per day. What means that you need to build 270 elementary schools for 1000 children each day just to get the most basic education for those children. Not to mention high schools and colleges and place for a job. This is simplified but it is obvious where this leads us.
Plus we are in the middle of global economic crisis, energy crisis and crisis of food and fresh water. I think that forming a logical conclusion about this is really not that hard.