free trade feeds the hungry. the solution is freedom.
Although these factors do come into play, the recent food shortages are due to a significant increase in meat consumption in the rising third world economies. Approximately 10 calories in consumed grain will result in 1 calorie of meat consumed. Small increases in meat consumption will make huge decreases in grains. The next largest impact is brought on by speculators manipulating the market and causing literally entire nations to begin hoarding to safeguard themselves. Subsidies, biofuels, and trade barriers are nearly unimportant factors. In fact, a recent report (last few months, not sure when) reported on treehugger.com claims that these factors account for less than 10% of the price increases over the last year.