Brishen Hoff writes: Unless earth is hit by a massive meteor, we will be vastly overpopulated for well over 40 years even if everyone is immediately sterilized. This means we will experience a die-off and more species extinctions. I suggest that earth's sustainable population is only 2,500,000.
Yes, that's million, not billion. If you think that is extremely low, think again. That is over 7 times the current population of all great apes (chimpanzees, bonobos, gorillas, and orangutans) combined! That is 10 times earth's population that persisted for the majority of our 2 million year human history! Perhaps if you think 2.5 million is too low for a global sustainable human population you are underestimating:
B) how much we've already permanently degraded earth's carrying capacity
C) how unsustainable our current "6th Mass Extinction" is
My estimate of 2.5 million as a sustainable global population is based on a viable hunter-gatherer population 10,000 years ago (when our numbers forced us into the low EROEI lifestyle of agriculture) of 5 million. I adjusted 5 million to 2.5 million because I believe our carrying capacity has been permanently degraded by at least 50%. There aren't as many species left and much of our land is now polluted, deforested, paved, infertile, etc. I think it is important to have a low enough population that a high EROEI hunter-gatherer culture is viable for all who desire it.
How badly we are overpopulated in the next 40 years depends on what we do. Quinacrine sterilization has great potential and offers real hope for a brighter future. Without harming anyone we can ensure maximum speed of population decline (which we already know is slower than desired) using Quinacrine sterilization which would have to be mutually-agreed upon by the majority and enforced just like other laws (eg: everyone has to pay taxes).