International environmental groups, including the United Nations, responded cautiously to the studies, saying that biofuels could still be useful. “We don’t want a total public backlash that would prevent us from getting the potential benefits,” said Nicholas Nuttall, spokesman for the United National Energy Program, who said the United Nations had recently created a new panel to study the evidence.
“There was an unfortunate effort to dress up biofuels as the silver bullet of climate change,” he said. “We fully believe that if biofuels are to be part of the solution rather than part of the problem, there urgently needs to be better sustainability criterion.”
The European Union has set a target that countries use 5.75 percent biofuel for transport by the end of 2008. Proposals in the United States energy package would require that 15 percent of all transport fuels be made from biofuel by 2022. To reach these goals, biofuels production is heavily subsidized at many levels on both continents, supporting a burgeoning global industry.
Syngenta, the Swiss agricultural giant, announced Thursday that its annual profits had risen 75 percent in the last year, in part because of rising demand for biofuels.
Industry groups, like the Renewable Fuels Association, immediately attacked the new studies as “simplistic,” failing “to put the issue into context.”
“While it is important to analyze the climate change consequences of differing energy strategies, we must all remember where we are today, how world demand for liquid fuels is growing, and what the realistic alternatives are to meet those growing demands,” said Bob Dineen, the group’s director, in a statement following the Science reports’ release.
“Biofuels like ethanol are the only tool readily available that can begin to address the challenges of energy security and environmental protection,” he said.
The European Biodiesel Board says that biodiesel reduces greenhouse gasses by 50 to 95 percent compared to conventional fuel, and has other advantages as well, like providing new income for farmers and energy security for Europe in the face of rising global oil prices and shrinking supply.
But the papers published Thursday suggested that, if land use is taken into account, biofuels may not provide all the benefits once anticipated.
Dr. Searchinger said the only possible exception he could see for now was sugar cane grown in Brazil, which take relatively little energy to grow and is readily refined into fuel. He added that governments should quickly turn their attention to developing biofuels that did not require cropping, such as those from agricultural waste products.
“This land use problem is not just a secondary effect — it was often just a footnote in prior papers,”. “It is major. The comparison with fossil fuels is going to be adverse for virtually all biofuels on cropland.”