NASA researchers say the accelerated destruction of Borneo’s forests contributed to the largest single-year global increase in carbon emissions in two millennia.
Source: NYT: Biofuel Mandates Have Been an Environmental Disaster - Foundation for Economic Education
Even if you believe the absolute worst case predictions about climate change, government intervention probably isn't desirable. Government intervention always results in unintended consequences and frequently results in making the situation worse than taking no action at all. Government mandates regarding biofuels are a perfect example.
While intended to improve the environment, it had catastrophically opposite results. Requiring vegetable oil in biofuels resulted in massive deforestation and the largest single year increase in carbon emissions in 2,000 years. Perhaps results such as these would not be so bad if politicians at least learned from their mistakes. However, sponsors of this law (Nancy Pelosi in this case) and others like it continue to defend them despite blatantly obvious catastrophic impacts. Keep these results in mind if and when the government starts legislating more things supposedly designed to reduce carbon emissions.