"Attention has focused on oil insecurity, and rightly so, but it is not the same as food insecurity. An empty gas tank is one thing, an empty stomach another. And while there are substitutes for oil, there are none for food." –Lester R. Brown, Plan B 4.0: Mobilizing to Save Civilization.
Here's a clip of Lester Brown from PBS's Journey to Planet Earth series on Plan B: Mobilizing to Save Civilization. Posted March 29, 2011.