Mr RB, I had one good argument that should elegantly show why population, or more specifically as I think neptune intends that population growth is the actual problem.
Look at the attached graph, and then very simply work out the rough approximation of the exponent required to create that curve..
Project it out 2.5 million years... The biomass would be well more than the mass of the earth, if not larger, I'd love someone to work the math out =)
Something will break. The doom and gloom scenario has to happen, there is no logical way the current growth rates can be allowed. Controlling them will be up to mother nature through means which will not be pretty and they are going to occur unless some method can be worked out within the next few hundred/thousand years to institute a global method of human population control.
Good luck with figuring out how to get people to go along with that!
Trust me, my doom and gloom scenarios are probably the kinder of what will actually happen. When the bow breaks in reality (as it invariably will) it will be something more than likely out of our personal comprehension. Look at the graphs of population growth at exponential rates and the extinction events that follow. They ALWAYS occur. There's no immediacy to it though in a human life span so people don't fear it. By the time the population fears this the events will already have come to the point where there is no way to do anything about it, outside of solutions that would now be considered morally incomprehensible. Sometimes the needs of the many outweight the needs of the few, but under these circumstance, there will eventually be portions of society with low population and a lot of power to control population (kill) and large masses of people that have no power. Choices will be made unless stability can be reached before then.
The next 200-1000 years are going to be the make or break for the human races modern long term survive-ability and there's not one current shred of hope that anything is or will in the future be done about this inherent system instability problems.
I think we're at what near 6 billion people? Once it hits 8 or 10 you'll see countries going into sheer panic, by then if methods immediately able to put this into place then the human race is doomed to be just another race of
https://en.wikipedia.org/wiki/Lemming, only we'll have no where to go.