Biofuel Crops Increase Carbon Emissions
The conversion of forests and grasslands into fields for the plants offsets the benefit of using the fuel, researchers find. Greenhouse-gas output overall would rise instead of fall
The rush to grow biofuel crops -- widely embraced as part of the solution to global warming -- is actually increasing greenhouse gas emissions rather than reducing them, according to two studies published Thursday in the journal Science.
One analysis found that clearing forests and grasslands to grow the crops releases vast amounts of carbon into the air -- far more than the carbon spared from the atmosphere by burning biofuels instead of gasoline.
"We're rushing into biofuels, and we need to be very careful," said Jason Hill, an economist and ecologist at the University of Minnesota who co-authored the study. "It's a little frightening to think that something this well intentioned might be very damaging."
Even converting existing farmland from food to biofuel crops increases greenhouse gas emissions as food production is shifted to other parts of the world, resulting in the destruction of more forests and grasslands to make way for farmland, the second study found.
The analysis calculated that a U.S. cornfield devoted to producing ethanol would have to be farmed for 167 years before it would begin to achieve a net reduction in emissions.
"Any biofuel that uses productive land is going to create more greenhouse gas emissions than it saves," said Timothy Searchinger, a researcher at the Woodrow Wilson School of Public and International Affairs at Princeton University and the study's lead author.
The studies prompted 10 prominent ecologists and environmental biologists to write to President Bush and congressional leaders Thursday, urging new policy "that ensures biofuels are not produced on productive forests, grassland or cropland."
Since 2000, annual U.S. production of corn-based ethanol has jumped from 1.6 billion gallons to 6.5 billion gallons -- supplying about 5% of the nation's fuel for transportation, according to the Renewable Fuels Assn., an industry lobbying group.