Lester Brown said at a talk at the Humphrey Institute, U of MN, today that our goal should be "saving civilization" - not sustainability. I smiled - another person who really doesn't like the term "sustainability." Of course, he's kind of a doomsday guy - water shortages caused by depleting aquifers and melting glaciers, along with inundation of Asian crop areas by rising seas will hit countries sooner than rather than later and threaten the very survival of our civilization. Just like the Mayans and other vanished societies who couldn't feed their people. He also warned about the growing number of failing states - like Somalia - where their crashes will affect us all.
He also made an interesting point about China drawing down its aquifers and looking to the US to buy up our grain. And since the Chinese basically own us by covering our debts, we aren't going to be able to argue. Goodbye cheap food.
He did say he was optimistic that we could make changes, but they better happen right now. He was also impressed at how fast changes are occurring. E.g., how fast biofuel ramped up - even though it was a bad idea - and how electric cars and wind farming are coming on line faster than predicted.
I don't know that "saving civilization" is the right handle either. Sounds a tad extreme. But I do believe it's going to get unpleasant until we find some technological fixes for providing water and food for the majority of people in the world.