What is the statement "increase in population = environmental decline" meant to convey. If it came from Bob Brown I would ignore it but when it comes from an intellectual like yourself I only can only assume you were not speaking mathematically.
Had you said "environmental decline (bears some proportionality to) population growth" perhaps you could have saved yytrium trotting out his Zeno paradoxes.
Perhaps Y, unlike any environmentalist I know has a mathematical equation which may even cover threshhold populations levels at which decline begins.
Intuitively I am generally in agreement with what I think you may have been vaguely hinting at.
