Two new studies published in the journal Science conclude that growing and burning biofuels actually increases net greenhouse-gas emissions and exacerbates climate change. The new research questions the assumptions of earlier studies, making sure to incorporate the effects of land-use changes into emissions calculations. When land-use changes are taken into account, turns out that plowing up rainforests and grasslands to make way for biofuel crops tips the balance, making biofuels more problematic than helpful. Biofuels proponents, including the powerful U.S. ethanol lobby, have for years cited figures asserting that biofuels made from crops like corn release about 20 percent fewer emissions overall than gasoline and that fuel from switchgrass emits about 70 percent less. One of the new studies, however, found that due to the impact of plowing up new fields, corn-based ethanol nearly doubles greenhouse-gas emissions compared to gasoline and that fuels made from switchgrass increase emissions by about 50 percent. Not all biofuels were net losers, though. The study authors suggested that producing biofuels from waste products still makes sense.