Please see J's prescient post on our potential for a sustainable future. Because this response is too long, it won't fit on his comment section.
Ahh, the big question. Can humans live sustainably? My answer is simple: the environment carries a big stick and isn't afraid to use it to beat the crap out of us.
A plethora of B-movie scenarios are proposed for the time of scarce resources. The formula goes like this...resource inequities turn the world into a dyad of "haves" and "have nots". Governments of wealthy nations allow their populace to live beyond their means and the rest of the world be damned. When other nations come with their hands out, wealthy nations undergo a rapid culture shift, moving toward overt nationalism, intense isolationism, and a return to conservative values. This is a not so subtle way of saying, "If those people had worked harder and saved for a rainy day, they might have what we still have. Aren't we great?", and is one of the most ugly and obvious examples of First World privilege imaginable. (But I digress.) Ultimately, resources become so scarce that the government can no longer contain the situation and falls. Then it's every man for himself. Individuals and families hoard the remaining resources, hole up in our houses, and shoot all who attempt to enter. This also fails. (Think every zombie movie ever made.) After the family unit fails, the survivors (almost always very young people with one or two progressive old folks who can pass on accumulated knowledge) congregate in happy communes and human culture is reset to a more sustainable level. Lather. Rinse. Repeat every ten millennia or so.
Our alternative scenario is that we skip all the government control of the situation and go straight to the hippy-dippy commune approach. Not. Gunna. Happen.
There is a third option, and that is the one I think you are proposing. Technology and self awareness can give people the tools they need to maintain a first world standard of living, curb population growth, and feed every mouth in need. All we need is a paradigm shift in culture to get it there.
I maintain it won't work. Oh, I think it is physically possible (people CAN be taught to live within hard limits and exhibit self-restraint) but the cultural jumping off point precludes it. Somehow, American culture has embraced the idea that we get to decide our own reality. And as goes American culture so goes the world. Let me give you an example. I spent this morning reading an internet board that I can only describe as the "To vaccinate or not to vaccinate: that is the question facing the inept" fiasco. There are people who are convinced that there is a conspiracy between the government and Big Pharma to kill them, that scientists are doctoring clinical trials purposely to bring bad product to market, and that any money made off of of meds renders the entire profession corrupt. Remarkably, these same people who think capitalism in the medical profession is bad also think that government programs that make medical services available to the masses are also bad. So capitalism AND socialism be damned. For fuck's sake, J, nothing can save these morons. In the absence of a real disease outbreak here in the United States (I don't think Americans believe it can happen here even if it happens in Europe) that wipes out a significant portion of the population, nothing will convince these idiots of the error of their thinking. I say, let them skip the vaccinations. Just kick their children out of public school, let them contract small pox, and corral their idiot behinds in quarantine camps.
But the point here is, when did it become okay for people to decide whether to accept facts, whether or not to "believe" scientific findings, and whether or not to act in a way that places not only themselves, but others in grave danger?
Humans have all the intelligence, knowledge and physical power necessary to actually bring ourselves back from the edge. But we won't. It is one reason that I think Obama might actually fail. The birthers, the anti-vaccination crowd, the climate-change deniers all seem to be living in an alternate universe that the educated, thinking man can't penetrate. They are so gripped in their own ignornace and conspiracy theories that they can't see what idiots they really are. While they may not be the majority, they are the lowest common denominator. And we "leave no idiot behind". The vast majority of people would rather wallow in ignorance right up to the moment that they trip into their mass grave. Humans are smart, but we aren't rational. We clasp to prior knowledge even when doing so harms us. If we were rational, religion would have disappeared generations ago. We can justify the most outrageous behavior.
Furthermore, a culture shift demands that the majority follow the rules. What biological population is able to control all its members?
I taught an entire course on environmental issues in which we discussed the problems of oil extraction and refining, the probem of carbon release and climate change, the problems of grwing population size and world hunger. I STILL had a kid tell me toward the end of the semester he wasn't going to give up his gas-guzzling car because "chicks dig it".
Humans are animals and please, tell me one biological population that is not (ultimately) controlled top-down (by predation, parasitism, viral attack, etc.), laterally (by competition), or bottom-up (by environmental controls). Tell me one.
Consider for example, our cultural expectation of monogamy. There are always extra-couple copulations. Why? Because even when there is the expectation of monogamy, individuals maximize their offspring's survival chances by investing in a variable set of genes. Sure, one of those offspring may be the most fit today, but what about when conditions change rapidly? Variation is good. Variation is the stuff of evolution. We will lie when culture works against our best interests. Sometimes we don't know why we act like we do, even when we act in defiance of cultural norms. I maintain there is always an element of biological determinism at work.
And unlike those in the "can humans exhibit enough self-restraint to prevent disaster", I propose that humans are controlled hardest by the limits set by the environment. If we improve technology we will merely increase the carrying capacity of the Earth. We will continue to fill all available space until the environment pushes back. We will bicker and fight and joust among one another like chickens in coop.
I think there are an enlightened few capable of sacrificing their own self-interests for the greater good. Perhaps they can change the mass culture, but I doubt it. Maybe these few are the founders of the hippy-dippy communes, but the masses are far too distrusting and stupid to make it work. I think martial law is just about the only way to achieve peaceful (?!!) sustainability. The other alterantive is to let the Earth take care of itself.
I realize I have rambled here and not stuck to the true intent of your original post, but I think maybe I was working through this as I wrote my response. It would be great if we somehow could educate our way into this sustainable future. I don't think I'm likely to see it in my lifetime, but I could be wrong.