As defined on Wikipedia (my favorite encyclopedia), permaculture is "a branch of ecological design and ecological engineering which develops sustainable human settlements and self-maintained agricultural systems modeled from natural ecosystems". It embodies the principles of caring for the earth as well as the people and setting limits as needed to sustain both. We have a finite amount of planet to work with here folks and it is getting pushed beyond its point of being able to sustain us. We need to start paying attention.
I heard a recent discussion between some of our city moguls here, that by 2050 at our current rate of growth, we would have to start shipping water in to keep the community growing. I see all kinds of problems with that, especially given that fresh water is going to be one of the limiting factors for the world in the near future (Learn more at the Stockholm International Water Institute). Perhaps we should be looking at controlled growth and living within our means rather than uncontrolled growth and scrambling for resources that might not be available. We need to have everyone living on this planet more responsibly, not just a few of us.