Population and the Environment

It seems to me that the debate about the environment is missing one very important element: population growth. I vaguely remember that people used to talk about this, but I never hear it anymore. The basic point is this: With 6 and a half billion people in the world, even if we cut our energy consumption in half, which no one is even seriously proposing, we would still be spewing out enough greenhouse gases to cause the global warming that is said to be occurring. Sure, by cutting back or stabilizing the amounts, we may be able to delay warming by 20 years or so. But is that really a satisfactory solution? So the question is, why not talk about population control? The answer, obviously, is that it makes all sides of the debate a bit uneasy, as once this principle is established, it is open to much abuse. Nevertheless, I don't see how we can really talk about the environment without addressing the issue.