Nestled among the UK media’s ‘comprehensive’ coverage of the possible impacts of the Renewable Transport Fuel Obligation was an interview on Channel 4 News with John Snow, Clare Wenner of the Renewable Energy Association and Friends of the Earth director Tony Juniper.

What irritated me most about the discussion was not the exceptionally limited content, the omission of weather conditions and a decade of global economic growth from the argument over rising food prices, or even the terminology of ‘good’ and ‘bad’ biofuels, but the following sentence from Clare Wenner: “The problem is so great that we need everything to make sure we reduce carbon in the transport sector.”

The size of the problem is already a matter of national debate, but what the hell does ‘carbon’ mean? There are two ways that most people will encounter ‘carbon’: 1) on the tip of a pencil or 2) in its slightly harder-wearing form, brilliant cut with an octohedral table and claw set in a white gold ring.