I thought it was 4500 yrs ..... LOL
It's actually closer to 300 to 360 million years ago, when most Carboniferous coal deposits were lain down originally as decayed organic matter, trees, vegetation, etc.
So, we as a society will use up the end result of 60 million years geological activity in a few hundred years and as a result pump all that extra carbon into the atmosphere, leaving our kids with an unknown legacy.
Scary in the bigger picture isn't it?