AGW: a bigger issue than overpopulation?

[CRH]

36. I have a question for you on the two child family, ...

being zero growth? ... Basically that is saying every person replaces themselves and quits. So your son and daughter in law replace themselves in twenty years, your grandson and granddaughter are born in another twenty. Using a life span of seventy years, at sixty years of age, six people exist from the original two parents. Seems to me population would at a minimum double every 35 or so years depending on death rates and life expectancy.

Now third world life expectancy is less than 70 years, and probably annual death rates per capita exceeds that of first world countries. Do these two factors off set the above scenario?

Is your statement above based on studies, or perception?