It looks like we really can't have everything. Western nations may have been feeling environmentally optimistic lately because of their embrace of biofuels made from corn or sugarcane -- a clean-burning, renewable energy source. But as ethanol producers have snapped up corn reserves, food prices around the world have spiraled up, causing scattered riots from Mexico to Haiti to Somalia. At a hastily organized summit meeting of the United Nation's Food and Agriculture Organization, officials warned that the present unrest could develop into a "global catastrophe." The statistics tell a serious story: