The clearance of grassland releases 93 times the amount of greenhouse gas that would be saved by the fuel made annually on that land, said Joseph Fargione, lead author of the second paper, and a scientist at the Nature Conservancy. “So for the next 93 years you’re making climate change worse, just at the time when we need to be bringing down carbon emissions.”
This shockingly high carbon intensity is due to the fact that cropland has to be cleared to grow the fuel crop. And if the farmer growing the fuel crop doesn't clear more land to do it, then someone else, responding to market pressure, will.
...Dr. Fargione said that the dedication of so much cropland in the United States to growing corn for bioethanol had caused indirect land use changes far away. Previously, Midwestern farmers had alternated corn with soy in their fields, one year to the next. Now many grow only corn, meaning that soy has to be grown elsewhere.
This implies that we need to stop trying to grow our fuel and start plugging our cars into some solar panels. I am intrigued by the possibility to use waste stocks to make biofuels, but our current thinking on them must change.
(Anyone think Khosla is listening?)