Business Green: Australia has surpassed the US as the world’s biggest per capita producer of carbon emissions, according to a report by a British risk consultancy. Analyst Maplecroft estimates that Australian CO2 output per head of population now stands at 20.5 tons annually, putting it ahead of the 19.7 tons emitted by the average American. By comparison, China — which emits more carbon overall than any nation — has a per capita average of about 4.5 tons. In India, where greenhouse gases …