Hmmm.

Something popped into my head today.
Just interesting.
Maybe I'll google on it a bit and see what happens.
BUT anyway, here it is.

Our system, our main system of life, is the planet earth, and the sun in relation.
Our system is a closed system for the most part. Self sustaining. Self reliant, but for the sun. Right?
Lets just all say right and get on to the next bit.

In a closed(relatively) system, you pretty much need the differant parts working together to maintain balance of the system.
So plants need water and sun, animals need plants and each other.
Weather contributes to all of this as well as geophysical aspects of the planets motion and so on.
Interdependant.

What does the earth use crude oil for?

It makes it.
It probably needs it for something.

So what happens when you use up a majority of that and replace it with like, water or something.
When an oil well is pumped they fill in the gap with water right. Pump water in while pumping oil out so that they are not just creating giant potential sink holes underground.
We know the make up and density and properties of petroleum are vastly different than water, so what impact can that have on the geological scale?
What is it that oil did geologically if anything?
I'm not saying it had to be doing something, but in general we know that interdependant closed systems don't really just create garbage without a way to use it. Otherwise they would eventually out pave themselves and collapse.
And the earth is a pretty solid system.

So what happens to the actual planet when we use up all the oil.
It'll take thousands of years to create more oil. If not longer.
So what did the planet as a system use oil for that it will be missing?

Lets just be cute about it and ask, does the earth use oil as a tectonic lubricant? Could we end up with more earthquakes, bigger, stronger, and so on with no grease on the wheels?
Will the planet lose mass over the long run?
If you chop of f a piece of a wood block, and burn it, but keep the smoke and gasses inside a bubble around the wood block, the block loses mass even though the gasses are still there inside the bubble right?
So what happens to the earth when it's mass changes?
Even on a small scale you could be looking at big changes over millions of years in the gravity of the earth/moon cycle right?

I don't know.
Just curious.
Like I said, popped in my head.