Speculators don't create commodity bubbles

The evidence does not support the claim that speculation has been the source of, or has exacerbated, the price increases. Indeed, expectations of future prices on the part of typical speculators, if anything, lagged behind contemporaneous spot prices in this episode. Speculators have often been “net short” (sellers) on commodities rather than “long” (buyers). In other words they may have delayed or moderated the price increases, rather than initiating or adding to them.

One revealing piece of evidence is that commodities that feature no futures markets have experienced as much volatility as those that have them. Clearly speculators are the conspicuous scapegoat every time commodity prices go high. But, historically, efforts to ban speculative futures markets have failed to reduce volatility.