Why is over-population never at the forefront of the climate agenda?

Agree. We need gradually decreasing global population, not rapidly increasing. If world population was less than 1 billion and we maintained current technology, had equitable distribution of resources, the decreased competition for natural resources would mean most of us could live comfortable on a 20-25 hour work week. Or less. 

With so few people, forests and fisheries would replenish themselves and we could heat our homes with wood, get abundant food via hunting, fishing, gathering. With so few people, dilution would be a natural solution to pollution. With so few people there would be no wars over good farm land or clean drinking water. 

And no, doofus, I'm not suggesting killing anyone. Just make fewer babies. 

partly "because that would be racist"

and some people have a hard time acknowledging that the average USAmerican consumes 300 times as much as the average Ethiopian.

it is politically incorrect to say that China and India have four or five times the appropriate number of people

China didn´t limit the number of children due to a climate agenda. Plus they made a big error by briefly introducing a one child policy in SOME areas - they did not foresee the fact that many women were aborting female babies due to a male having better life prospects and they ended up with a generation where there is an imbalance between males and females (not enough females).

stupidity. over population is the main problem in the world

China limited the number of children a woman can have YEARS ago.