I learned (and believed) that by the 1990s overpopulation would lead to worldwide starvation and the exhaustion of key minerals, metals and oil, predictions that failed utterly. Politics polluted the science and made me an environmental skeptic. Nevertheless, data trump politics...
He should have stopped here...
In other words, what he is saying is like a seminar caller, "I used to be a [skeptic, Republican, conservative] but the failure.... blah, blah, blah.