Guardian: As I’ve been reminded at this week’s Carbon Expo in Barcelona, carbon markets need more buyers. I’ve met a large number of people who are eager to get their climate-busting solution funded by selling permits on the carbon trading market. Some want to build windfarms and other renewables, others wish to prevent forests being cut down, others want to bury charcoal – fertilising soils and trapping carbon – still others want to seed the oceans with micro-nutrients to bring the oceans’ ailing …