Speculators get a bad rap, but actually play a pretty important role in futures markets by aiding price discovery and providing a more efficient transfer of risk between hedgers. To make money they need to try and accurately forecast where prices will move, and to do so will incorporate any and all available information - it is literally their job to try and know everything there is to know about what will effect commodity prices.

There has also been quite a bit of academic research on the effect of speculation in futures markets, and by and large the conclusion seems to be that they help, rather than hurt these markets and rises in commodity prices have been driven mostly by external factors [1].

[1] http://www.forbes.com/2011/05/24/oil-speculators-are-your-fr...