Marketed as a "green" energy source, in recent years biofuel use has increased around the world. Global ethanol production tripled between 2000 and 2007, increasing from 17 billion to more than 52 million liters. Biodiesel expanded 11-fold, from less than 1 billion to almost 11 billion liters. And these fuels together still only provided about 1.8 percent of transportation fuels globally. It looks like development has come at the expense of research, though. Last week Friday, a major UN report stated that biofuels' effect on the environment has not yet been sufficiently explored, and that a more "advanced approach" is needed beyond the study of its production and use in order to match growing global production. The report, the first to be released by the United Nation's Environment Programme's (UNEP) International Panel for Sustainable Resource Management, added that all factors and uses of biomass must be considered in order to measure its harm to the environment, including food, fibers and fuel.