Do not be tempted to think that the following isn't true 
:-).

> Sustainability is about maintaining for the long term (at 
> least until
> a new ice age

Ice age cycles are about 100,000 years.
You get about 90,000 years of glaciation (defined as about 
1000+ feet of ice above where most people reading this are 
sitting now) followed by about a 10,000 year "interglacial" 
period. Actual cycle lengths vary somewhat. But not too too 
much. So ...

> Maybe I'm shooting high.

As the current interglacial has lasted about 12,000 years so 
far, and is thus about 2,000 years beyond it's use by date 
already, your sustainability efforts may well last until the 
next ice age. Alas. Just as well we have Global Warming ... 
:-)


        Russell




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