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When will the world's oil run out? It's a hotly debated question among energy experts, geologists, politicians, and others-and this term is at the center of the debate. It refers to a point, possibly in the near future, at which global oil production will reach a maximum, and then start to decline. A geologist named M. King Hubbert first came up with the peak oil theory, so it is sometimes referred to as Hubbert's Curve.