Here For a Good Time, Not a Long Time
With a world population above 6.5 billion and climbing, almost every last one aspiring to a life with more material wealth, the analogy it brings to my mind is of the most popular bloggers, who find that as their site grows in readership, they have to be careful who they link to, lest they overwhelm somebody's server by directing a heavy flow of traffic there. As a site grows in readership (as humanity grows in population and power) it gets easier and easier to overwhelm the other parts of the ecosystem. Want to build electric cars or solar cells for 1 million people and there are plenty of resources - try to do it for 6.5 billion and everywhere you turn you wind up running into constraints. Try to feed 1 million people with fish and there's no problem. Try to feed billions and you find yourself eating your way down the food chain, depleting one formerly rich feeding ground after another. Can 7,8,9+ billion people live on this planet in affluence? I guess we, or the next generation will find out.
But on the plus side, life is looking up on a more personal level, so I can extend a little optimism that we'll be able to deal with enough of our problems well enough to avoid bringing the whole thing down, at least not until after I've passed on.