May 11, 2007 — For years, researchers studying the effects of climate change on agriculture have focused on two big issues: the availability of water and the impact of increasing carbon dioxide levels in our atmosphere. Carbon dioxide released from our cars and factories is the number one cause of global warming. But scientists have long theorized that more of the gas in the atmosphere could actually help grow bigger plants. New research is challenging that assumption. David Sommerstein went to the breadbasket in Illinois to learn more.