Sorry, a bit of sarcasm. But seriously, the word "sustainable" has been misused by so many for so long, that I think it has lost its meaning. As Hemingway supposedly said, "words lose their meaning through loose usage." Nothing is sustainable if you run the timeline out far enough, and anything is sustainable
for short periods. "Renewable" is another such word, and don't even get me started on "natural" (as opposed to what--supernatural?). Okay, off my grammar nazi soapbox.
Someone on the Forum has or had a by-line that said (more or less), "the oil age will end long before we run out of oil, just like the Stone Age ended long before we ran out of stone." Whatever energy and other resources we use now will continue for a long time, and overlap whatever new resources we discover or create, as the old becomes less economically attractive and the new becomes more so. Thus, it doesn't matter whether any resource is sustainable. When it becomes uneconomical, we will replace it with something else. Always have, always will. It's what we do.
