Register: Good science news (or bad, depending on your point of view) has arrived with two reports on the carbon footprint of biofuels, in the paper edition of Science magazine. They deal serious damage to the belief – which up to now has been driving the biofuel bubble – that stepped-up ethanol production in the US is an answer to global warming. Writing in "Use of US croplands for Biofuels Increases Greenhouse Gases Through Emissions for Land Use or Change," Timothy Searchinger and …