Though the relative importance of the reasons is difficult to assess, the list itself seems clear (the price of oil, a growing middle class in China and India with an increasing demand for meat which requires more grain for feed, droughts likely due to climate change, Western government subsidies for biofuels like corn ethanol).
But I wonder if we shouldn't consider a different aspect of this. As the New York Times points out:
Even the poorest fifth of households in the United States spend only 16 percent of their budget on food. In many other countries, it is less of a given. Nigerian families spend 73 percent of their budgets to eat, Vietnamese 65 percent, Indonesians half.What is wrong with our world that so many people are living so close to the edge? Hmmm ...
Update 14Apr2008: The graph below was produced using Technorati. It shows the number of blog posts (in "any language" on blogs with "some authority") containing "food crisis". Too bad most of us are at least 6 months late.