NEW YORK ( TheStreet ) -- Michael Ruppert tacitly believes that five billion people will be wiped off the face of the earth sometime in the next few decades. His proof? One chart. Ruppert makes the unappealing but hard to refute argument that human population growth is a direct and total result of the existence of cheaply available crude oil. You can see his entire argument laid out in the chilling documentary "Collapse." But in short, Ruppert posits that population growth from 1900 to 2000 was almost entirely the result of a steady supply of crude oil. For the record, we have likely passed the point of peak oil production. I know there are some people out there who don't agree with that statement. Some of them might even be reading this letter right now. But in the oil exploration and production industry, there is little argument. There just isnâ¿¿t. If you have any proof that we have yet to hit peak oil production (in other words, you have oil production numbers that are on the rise, not on the decline) then I'd love to see it. With peak oil production in our rear-view, we will necessarily produce less oil in the future -- until eventually oil is too expensive to bring to market. Without crude oil to fuel ongoing growth in industrialization, technology, commerce and agriculture, the five billion people on this earth who only exist because of crude oil will die. That's his argument, anyway. He claims that we've currently only seen one side of the bell curve -- the growth side, and that sometime in the next few decades, we'll see the other side: the decline side. I don't know if I agree with him completely. I do think that his basic facts are correct: oil is a dwindling resource. We're not running out of oil, for the record, but we are running out of the cheap oil. Oil is going to get much, much more expensive -- and not just because it's getting more expensive to pump out of the ground. It's getting additionally expensive, because -- to paraphrase Energy Economist Jeff Rubin, governments around the world are trying to spur growth by replacing cheap oil with cheaper and cheaper currencies.