Recent evidence out of Brazil buttresses that point. A team of researchers headed by David Lapola of the University of Kassel in Germany found that 90 percent of Brazil's sugarcane expansion in the last five years displaced cattle rangeland, forcing ranchers to push into the forest. Lapola's team concluded Brazil's plan to expand biofuel cropland over the next decade will push displaced rangeland into more than 47,000 square miles of forest and another 17,760 square miles of other native habitat.
That's a patch of land equal to New York and New Jersey combined.
"It seems like for the U.S. corn ethanol, there would be a lot of friction with food crops and (indirect land-use changes) not only inside the U.S. but abroad, too," Lapola said via email from Germany.
The Obama Administration insists it used the most recent, accurate science. Briefing reporters as the change was unveiled last week, Agriculture Secretary Tom Vilsack noted the science of crop productivity "is constantly evolving."
EPA Administrator Lisa Jackson stood by her agency's scientists amid charges that the agency bowed to pressure from the farm lobby. "I don't agree that we changed the science to fit any outcome," she said. "I would not sign a rule if I didn't believe we had met the requirements of the law."
But in some ways the carbon savings from corn ethanol might be a secondary – or even moot – point.
Announcing the change, the administration highlighted biofuels' potential to create jobs and offer energy independence. President Obama, speaking to governors about the policy shift last week, mentioned climate change once: "Even if you don't believe in the severity of climate change, as I do, you still should want to pursue this agenda."
Plus the administration – and many in the ethanol industry – views corn ethanol as a bridge to less carbon-intensive biofuels. "We believe that's where the market is going," Vilsack said.
But the push to develop corn ethanol has a cost, and NRDC's Greene wonders if that's the wisest policy choice. "It's folly to do what we're doing today, which is mandating it, giving it multiple tax credits and still throwing other government subsidies at it," he said.
"We're bribing the market.... That's $5 billion a year that we could be using to help our farmers and help our industry get to the next generation of this stuff."
Lapola, looking at Brazil, notes some biofuels don't have the huge carbon footprint of sugarcane, soybean or corn. But so long as governments keep a sharp eye on land-use changes, he thinks biofuels make a good "workaround" for petroleum fuels.
"A workaround, but not a complete solution," he added. "The point is that from now on we need to evaluate more carefully our energy matrix to not incur in the same mistakes we made with petroleum."
This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.