World Population imbalance between the sexes

[Klaus]

Population drops to 5 billion in 32 years. This is really simple (mortality rates in other countries are obviously different than the US, and overall are going to be higher), but you can see that the decline is pretty linear until the bulk of the population moves into the higher age ranges.

Neat - and I believe supports my back-of-the-envelope no-births model. And to correct my earlier statement, population decline *is* exponential, but only on a lag of 60ish years. Growth is exponential lagged only 18ish years. But with a lag of 60 years before the 1 year olds start to die faster than average, the world population simply cannot crash exponentially before 2070 or so with ordinary mortality.

-Jester

For giggles, I added a birthrate component to my model. I didn't want to get too crazy with details, so I put it in as if women were 50% of the population, and each woman had X kids when she was 25 years old. If I set X to 1, the population peaks at around 7.1 billion and drops back to 5 billion after 56 years. If I set X to 1.5, peak is about 7.8 billion (25-30 years in) and drops back to 5 billion at about 85 years. X=2.03 is a very long population decline. X=2.04 is ever increasing population (10 billion after about 300 years).