Reuters: Australia has recorded its largest transaction in carbon emissions, with 20,000 tonnes of carbon sold forward at A$21.50 ($19.51) a tonne, a carbon broker said on Friday, as the nation prepares to curb greenhouse gases. Australia, the rich world’s largest per-capita emitter of greenhouse gases, plans to cap emissions from 2010 and introduce a carbon-trading system where businesses that pollute less can sell emission credits to those firms that pollute more. “I believe it …