Well, Fools, it appears that I'm not the only energy Chicken Little currently clucking about a likely insufficiency in global crude supplies. In fact, a report issued Monday by the Paris-based International Energy Agency (IEA) should probably cause Foolish investors to cast a closer eye at the likes of ExxonMobil (NYSE:XOM), ConocoPhillips (NYSE:COP), BP (NYSE:BP), and perhaps such big oilfield service companies as Baker Hughes (NYSE:BHI) and Weatherford (NYSE:WFT).

According to the agency's new Medium-Term Oil Market Report, world oil demand is now anticipated to rise faster than supply during the next five years. Specifically, the advisor to 26 industrialized nations expects global demand to reach 95.8 million barrels per day by 2012, up from usage of 86.1 million daily barrels expected for this year. In releasing its report, the agency noted, "Despite four years of high oil prices, this report sees increasing market tightness beyond 2010."

And if those predictions weren't enough, the new report envisions that additions to global refinery capacity will lag earlier expectations and that there will be a greater reliance in the West on OPEC production. Nevertheless, "project slippage and geopolitical problems" have led to a 2-million-barrel-per-day reduction in the cartel's expected spare productive capacity by 2009.

But despite the agency's reference to geopolitical problems, my feeling is that reports of this type, while seeming to cast a dire look in the direction of energy capacity, often understate the likelihood of major disruptions in Iran, Iraq, Nigeria, Venezuela, and even Saudi Arabia or Russia. In this case, the agency's numbers are predicated upon no expected net expansion of capacity in Iran, Iraq, and Venezuela, along with the eventual reintroduction of currently shut-in production in Nigeria. That's all possible, but so is a net decline in capacity in one or more of those international tinderboxes.

At the same time, it's impossible to predict accurately the likely effects of hurricanes on U.S. production and refining capacity. Indeed, essentially all we know is that in the world of energy, negative surprises are far more likely than are serendipitous events, like a giant new field coming on stream in, say, Rhode Island or France.

Now, Fools, I'm fully aware that volatility in energy is the norm, and so I won't recommend overweighting in the group. But if your portfolio is light on this important sector, prudence would seem to dictate a reconsideration of your allocations.

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Fool contributor David Lee Smith does own shares in Baker Hughes, but not in the other companies mentioned. He welcomes your questions or comments. The Motley Fools has a disclosure policy.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.