As the debate over what do about human-caused global warming increases and "green fever" sweeps the nation, many environmentalists and politicians have viewed biofuel as a logical replacement for fossil fuels.
But two new studies released Thursday call into question the global movement toward biofuel. According to these researchers, production of biofuel actually contributes to global warming, doing more harm than good.
The studies, one conducted by Minnesota-based Nature Conservancy and one by Princeton University, examined the same issue: What environmental impact does growing vegetation used for biofuel have on global warming?
U.S. demand for ethanol crops like corn, soy and switchgrass has resulted in the conversion across the globe of natural habitats – like grasslands and rainforests – into fuel-ready farmland, according to the studies. That development has released mass amounts of carbon into the air, researchers said.
"You ask the world's farmers to produce energy and that's going to take additional land and that land has to come from somewhere. Unfortunately, much of it is coming from our natural ecosystem. What's the consequence of that?" Joe Fargione, the regional science director for the Nature Conservancy and the lead author of one study, told ABCNews.com. "If you imagine a grassland and a cornfield, there's much more carbon in the grassland soil. When you convert a grassland into a cornfield, that carbon has to go somewhere. It goes into the air as carbon dioxide and contributes to global warming."
"Any biofuel that causes the clearing of natural ecosystems will increase global warming," he continued.
In the Princeton study, which was led by Timothy Searchinger, a German Marshall Fund fellow and a researcher at Princeton University, numbers told a striking story.
Past data that has outlined the benefits of biofuels didn't include the issues surrounding the impact of land use and the carbon released into the air as a result, both studies said.
Using models that calculated carbon emissions in various countries, the Princeton researchers found that the production of corn-based ethanol nearly doubles greenhouse emissions over 30 years and increases greenhouse gasses for 167 years. Similarly, biofuels made from switchgrass, if grown on land originally intended for corn, increase carbon emissions by 50 percent.
"By excluding emissions from land-use change, most previous accountings were one-sided," the researchers wrote. "Because they counted the carbon benefits of using land for biofuels but not the carbon costs – the carbon storage and sequestration sacrificed by diverting land from its existing uses."
"Twenty percent of CO2 emissions come from land use change and deforestation," Searchinger said. "We're simply transferring the problem ... from the fossil fuel side to the land-use side" when we produce biofuel.
Researchers in the Nature Conservancy study, which has been going on since March 2007, found nearly identical results. In this study, researchers compared the amount of carbon in the air in natural ecosystems and crop land around the world.
"There is three times as much carbon in the plants and soil as there in the air," Fargione said. "This is a globally significant concern that is dramatically contributing to global warming."