I am trying to recollect the name of a English-language sci-fi novel dealing primarily with a dystopian future with

* Explosive population growth
* Widespread global pollution
* one of the antagonists is a cult leader who preaches to people to voluntarily commit suicide to reduce burden on society
* There is some backdrop story to this antagonist in which he is revealed to be a sadist torturing little animals
* The protagonist races against time to find a solution for the pollution which is becoming lethal
* he uses notes from his late son who was a researcher in the field to follow a trail. The research notes are in a data pad that self erases if certain questions, devised by his son, are not answered when reading it
* the solution he finds at the end is a secret lab that has been growing super-intelligent next generation kids who have the potential to solve all the problems.

I remember reading it around 2002. Though I think it is a 1970-80s work.

Can you help me find the name of the novel?