I believe, to prevent civilization collapse and environmental ruin and to establish 400 years of sustainability (est. life of hydro dams) at developed world lifestyles, the earth's population should be about 50 million.
I propose humankind implements a limitation of 500,000 births per year. This lottery issues 500,000 birth permits. Universal, but reversible, sterility allows permit effectiveness. Lottery for permits -- implemented by civil law created by majority vote of global population (Mutual coercion, mutually agreed upon G.H.)
Today, with 140 million births expected this year, 500,000 permits would allow only 1 birth for every 280 women that normally giving birth. But because at least half of these births are unwanted the restriction would inhibit 139 of every 140 women who wanted children. Only 1 woman would produce a baby for every 140 who wished to do so.
This is very painful. However, this pain does not last very long only 30 to 40 years. Every year, a cohort of 50 million women is replaced by cohort of only 1/4 of million women, after the last large cohort stops producing babies, only the 35 cohorts of 1/4 million are left in the pool to be abused by the lottery.
What is interesting is that those now in the fertility pool are not abused. If you follow the calculations below these women can have the children they want.
To maintain the population,
This means that:
By contrast, if in an alternative plan
Thus culture should leave unchanged the genetic bias to have children, but allow