TIME.com, Ecocentric blog; Bryan Walsh, March 7th, 2011

Another day and there's another study that undermines the case for biofuels as an eco-friendly source of energy. This time it's the booming palm oil plantations of Southeast Asia, which yield the raw ingredients for biodiesel, used most often in Europe. Activists have been warning for some time that the growth of palm oil is leading to deforestation in Southeast Asia, where forested land has often been cleared to build palm plantations. Malaysia and Indonesia produce 87% of the world's palm oil, and the combined harvested area for oil palm has reached 6.5 million hectares (ha), up fourfold from 1990 levels.

That's an environmental threat that has impacts both local and global. Deforestation can lead to the loss of habitat for species that depend on the forest, and the cutting down and burning of trees worldwide is responsible for some 15% of global carbon emissions.

Now a study on palm oil plantations published in the March 7 Proceedings of the National Academy of Sciences confirms what environmentalists have feared: palm oil plantations create deforestation and hurt biodiversity. Researchers from the Eidgenössische Technische Hochschule in Zurich and the National University of Singapore looked at oil-palm plantations in peninsular Malaysia, Borneo and Sumatra and found that 880,000 ha of tropical peatlnad—about 6% of the total territory—had been converted to palm oil plantations by the early years of the last decade.

That conversion has led to biodiversity loss that ranges from 1% in Borneo to 12.1% in peninsular Malaysia—equivalent to the extinction of some 46 species. Carbon was emitted in the land-use changes as well—some 140 million metric tons of carbon were added to the atmosphere thanks to the clearing of existing forests, even as the loss of those peatland forests further reduced the ability of the landscape to sequester carbon.

By 2010, a total of 2.3 million ha of peatswamp forest had been cleared—an area roughly the size of New Jersey. The study found that up to the early part of last decade, most of the deforestation occurring in peatlands wasn't due to oil palm—but that will likely change in the future if the industry keeps ramping up.  There's every reason to expect it will—Indonesia has pledged to double oil palm production by 2020.

The palm oil industry has its defenders, who point to the jobs and economic growth that can be created by expanded plantation. (See this study by the pro-palm oil NGO World Growth, which estimates that the industry directly and indirectly supports nearly 20 million Indonesians alone.) And unlike corn ethanol, palm oil plantations don't necessarily compete directly with food—the product is often used as a cooking oil, in addition to providing biofuels.

But the PNAS study demonstrates that as the palm oil industry grows in Southeast Asia, it will inevitably compete—and beat—native forests, with dangerous consequences for biodiversity and carbon emissions. In a world where population is expanding and wilderness is shrinking, it's becoming increasingly obvious that we can't farm our way out of our energy problems with biofuels.