PRAGUE — When United Nations Secretary General Ban Ki Moon recently visited Antarctica, he was impressed by the melting ice he saw there. Then he was in Brazil, where he was impressed by the country's use of biofuel to power a quarter of its automotive traffic. Oil pressed from rapeseed can be used as diesel fuel, and corn or sugar beets can yield ethanol to replace gasoline.

The U.N. and many countries officially share the view that biofuel is one option in fighting climate change. The United States generously subsidizes production of ethanol from corn, with output there currently growing 12 percent annually and almost 10 percent worldwide. EU countries subsidized biofuel production with 3.7 billion euro in 2006, and intend to cover 8 percent of their motor fuels from biological sources by 2015 and 20 percent by 2020. The Kyoto Protocol allows countries to meet their target reductions of CO² emissions by substituting biofuels for fossil fuels.

But is it really a wise and ethically acceptable strategy to burn food rather than eat it? If we allow food to be used to produce biofuels, food prices will be linked to the oil price, as the head of the German farmers association happily announced. Indeed, food prices are currently increasing in Europe, because more and more farmland is being used for biofuels instead of for food production.