From the Economist:

At the start of 2011 the food industry is in crisis. World food prices have risen above the peak they reached in early 2008. That was a time when hundreds of millions of people fell into poverty, food riots were shaking governments in dozens of developing countries, exporters were banning grain sales abroad and “land grabs” carried out by rich grain-importing nations in poor agricultural ones were raising awkward questions about how best to help the poor.

This time, too, there have been export bans, food riots, panic buying and emergency price controls, just as in 2007-08. Fears that drought might ruin the current wheat crop in China, the world’s largest, are sending shock waves through world markets. Discontent over rising bread prices has played a part in the popular uprisings throughout the Middle East. There are differences between the periods, but the fact that agriculture has experienced two big price spikes in under four years suggests that something serious is rattling the world’s food chain.

For more, see: The 9 billion-people question