In a Washington Post article David Tilman and Jason Hill argue that the increased use of ethanol in fuel is pushing up corn prices in Mexico making the staple food unaffordable to the country's poor and will lead to the destruction of the Amazon rainforest as more a more land is cleared for corn production. This in turn will lead to more global warming as one of the world's great carbon dioxide sinks is destroyed.
If every one of the 70 million acres on which corn was grown in 2006 was used for ethanol, the amount produced would displace only 12 percent of the U.S. gasoline market. Moreover, the "new" (non-fossil) energy gained would be very small -- just 2.4 percent of the market. Car tune-ups and proper tire air pressure would save more energy.