Global warming was a mainstream view till not too long ago too.
Yes or no?
If not, why not?
Why don't all the extra children born into poverty provide an economic boon to the nations with absurdly high birth rates?
How do you reconcile your out of the mainstream view with this reality?
Global warming was a mainstream view until data demolished it.
Where is the data undercutting the widely reported and almost universally acknowledged EXPANDING human population?
Even you admit we may well climb to NINE BILLION PEOPLE!
That is both much more likely and a graver threat to human well being than your mythical decline in human population, based upon an innumerate assumption that the slightly declining birth rates of 7 billion people will lead to demographic collapse, instead of rapidly approaching 8 billion people and climbing.