One of the defining characteristics of our age is that we have devised countless ways to consume more stuff by borrowing money that posterity will have to pay back and by consuming non-renewable resources without regard for the effect their depletion will have on future generations.
This graph is an attempt to lay out how much fossil fuel remains on earth and when it will be depleted. The End of Oil trope has been around for a long time and has been "disproven" every time the price of oil falls, so the timing of this chart is naturally speculative.
What is indisputable, however, is that we will run out eventually. This graph says we have 90 years left. The accompanying article says, basically, we don;t have a plan B.