Consumers vs. Conservers

Some environmentalists see a silver lining in the current economic downturn.  They believe that a recession will reduce consumption and have the potential to create a new "normal" level of consumption.  An opinion piece by Brad DeLong suggests that humans have an insatiable appetite for consumption.
 

And everybody I know finds it very difficult to imagine how people can survive on less than one-third of what they spend—never mind that all of our pre-industrial ancestors did so all the time. There is a point at which we say "enough!" to more oat porridge. But all evidence suggests Keynes was wrong: We are simply not built to ever say "enough!" to stuff in general.
Our economic appetite - THE WEEK.

This issue is at the core of the discussion of green demand.  Over the last several hundred years, the price of most products has dropped relative to income.  This has resulted in increased living standards in the developed world and more consumption.  Is there consumer value to conservation?  Is sustainable more expensive?  What if we can't consume as much in a "sustainable" world? 

hat tip - Andrew Sullivan