Clearing vast tracts of land for biofuels production would hinder—not help—the effort to slow global warming, according to two new studies published in the journal Science. Although such fuels emit less greenhouse gases than fossil fuels, clearing forests and other native ecosystems releases carbon dioxide from plants and soil through fire or decomposition. Additionally, cropland absorbs less carbon than the native ecosystems it replaces.

One study, conducted by researchers with the Nature Conservancy and the University of Minnesota, quantified emissions of carbon dioxide from the clearing of native ecosystems. Lead author Joe Fargione, a scientist with the Nature Conservancy, said the study "asks the question 'is it worth it?' And surprisingly, the answer is no."

Fargione and his co-authors found that converting ecosystems such as rainforests and into fields of corn, sugarcane, palm or soybeans, would release 17 to 420 times more carbon than would be gained by replacing fossil fuels. The researchers identify this release as a "carbon debt," which must be paid before biofuels produced on the land can be credited with reductions in greenhouse gases. They found it would take more than four centuries to pay off the carbon debt incurred by converting Indonesian peatlands for palm oil plantations. Soybean production in the Amazon would take 319 years to offset the costs of production.

The second study found that diverting food crops into biofuel production leads to the clearing of yet more native ecosystems for crop production. Diversion of US corn supplies to ethanol is having a global effect, the researchers say, requiring the conversion of more land to corn production and driving up prices. Estimates that corn-based ethanol would result in 20% reductions in greenhouse gases compared to fossil fuels are wildly inaccurate, according to the study by researchers at Princeton University, Iowa State University and the Woods Hole Research Center. (Environment News Service, Feb. 8)

See our last posts on biofuels and the climate crisis.

See also our special report, "Global Warming and the Struggle for Justice," by Brian Tokar