Australia posted its biggest annual reduction in greenhouse gas emissions in 24 years of records in 2013 as the carbon tax helped drive a large drop in pollution from the electricity sector.

The latest greenhouse gas inventory, released online without fanfare by the federal government, showed annual emissions excluding changes in land use were estimated at 538.4 million tonnes of carbon-dioxide equivalent in 2013, down 0.8 per cent on the previous year.

Biggest drop in 24 years: Emissions are falling in the power sector - for now.

While the final figures may be revised, the annual drop is likely to exceed the only two other years of emissions falls – in 2009 and 2010 – since the tally began in 1990.

The electricity sector reported emissions fell 5 per cent last year, with all but one other sector showing an increase. The carbon tax has its most direct impact on power generators, which account for about one-third of Australia’s emissions outside changes to forest cover.