Biofuels are an energy source derived mainly from plants and widely thought to offer a better alternative to petroleum and other fossil fuels. In particular, when biofuels are burned to generate electricity or power a car, they produce lower emissions of carbon dioxide, the gas largely responsible for human-caused climate change. Concerns do exist about other consequences of switching to biofuels. For instance, using biofuels to meet the energy needs of even a few industrialised nations would likely require converting large amounts of forest and land now utilised for growing food to the production of crops only suitable for manufacturing biofuels. Such land use change could harm biodiversity and also reduce food availability for some of the world’s poorest people. Yet the planet-wide threat posed by climate change is so significant that a transition from fossil fuels to biofuels must be pursued.