The only way speculation can have a persistent effect on oil prices, then, is if it leads to physical hoarding — an increase in private inventories of black gunk. This actually happened in the late 1970s, when the effects of disrupted Iranian supply were amplified by widespread panic stockpiling.
But it hasn’t happened this time: all through the period of the alleged bubble, inventories have remained at more or less normal levels. This tells us that the rise in oil prices isn’t the result of runaway speculation; it’s the result of fundamental factors, mainly the growing difficulty of finding oil and the rapid growth of emerging economies like China. The rise in oil prices these past few years had to happen to keep demand growth from exceeding supply growth.
Saying that high-priced oil isn’t a bubble doesn’t mean that oil prices will never decline. I wouldn’t be shocked if a pullback in demand, driven by delayed effects of high prices, sends the price of crude back below $100 for a while. But it does mean that speculators aren’t at the heart of the story.
Or, said another way, there is no big pool of oil.