Blaming and curbing food speculators

With wheat prices up 50% since June and Russia banning grain exports, the media is all over "the next food crisis." I'm disappointed that former IFPRI Director-General Joachim von Braun appears to lay much of the blame on those evil speculators.

The setting of prices at the main international commodity exchanges was significantly influenced by speculation that boosted prices. Not only are food and energy markets linked, but also food and financial markets have become intertwined – in short, the “financialisation” of food trade. There are increasing indications that some financial capital is shifting from speculation on housing and complex derivatives to commodities, including food.

von Braun is right to call for "accelerated public investment in agriculture." But I believe it's misleading to imply that speculation-curbing measures such as requiring larger capital deposits of traders will really help moderate either prices or volatility. For prices, note how prices also rose in non-speculatable food commodities in 2008, and for the impact of speculation (a.k.a. liquidity) on volatility, just remember the onions.

I'm not 100% sure I'm right on this, but I would have appreciated a more robust substantiation of the claims about speculation's impact from someone of von Braun's stature.