"Won't happen. Can't happen. The Earth can't support the whole world living at the level of the average Amercian."
I think this is an overly pessimistic stance. No matter if people are far right conservatives, neo-liberals, or Greenpeace activists, we all want a high quality standard of living (this does not necessarily imply owning three polluting SUVs btw) and a clean environment and I think there are encouraging signs in this direction.
The environment *is* being improved in much of the western world. Even more importantly, major parts of the third world are reaching our standard of living and are starting to care about the environment as well. Food on the table will always be a higher priority for the poor than any abstract greenhouse problems with no immediate impact on their everyday life.
There have been predictions about natural resources (oil, minerals, etc) running out on numerous occasions in the last century and each time they have been proven wrong.
Let's see in 20-30 years time from now if the world isn't better off than it is today. I'm willing to bet that it will be.
