"An inability for the production capacity of future oil resources to adequately make up for the shortfall of the existing declining oil supply on a world scale."

That's the best, most concise defintion I've read so far.

I agree, but it has one problem: the Avg. Joe can't maintain enough interest to parse a sentence that complex and, so, will not get the message. This is a problem we face in educating others. We need a simple way to make a clear point.

The problem of Peak Oil is not because "oil" is almost gone. Go outside and look at the road in front of your house. That black stuff? That's what passes for "oil" these days. Picture the old oil gushers. Now picture the road. Gusher. Road. How much more work and energy do you think it takes to turn tar into oil? How fast could you do it? That's much of the half of oil that's left. And that's why Peak Oil isn't about how much "oil" there is. It's about how fast we can get it out of the ground vs. how fast we are using it.

Hmmm... that needs some paring down...

The problem of Peak Oil isn't that "oil" is almost gone. Go outside and look at the road in front of your house. That black stuff? That's what passes for "oil" these days. Picture the old oil gushers. Now picture the road. Gusher. Road. That's the half of oil that's left. And that's why Peak Oil isn't about how much "oil" there is, it's about how fast we can get it out of the ground vs. how fast we are using it. And it's coming out the ground more slowly all the time.

Or...

"An inability for the production capacity of future oil resources to adequately make up for the shortfall of the existing declining oil supply on a world scale."

Peak Oil: we're using it faster than we can get it out of the ground, and we're getting less and less each year.

Or whatever.... anyone else got something short, sweet and understandable to the uninitiated without too much thought?