Worst dust storm in 70 years hits Tocal

A severe dust storm, experienced by most of eastern Australia on 23 September 2009, turned the early morning sky an eerie sepia colour as red dust swirled across the landscape.

A decade of drought and a month of strong westerly winds combined to send millions of tonnes of dust from the Lake Eyre basin over NSW, Victoria and Queensland, Monash University geography and environmental science head Nigel Tapper reported (SMH 23.9.09).

The dust plume stretched 600 kilometres along the NSW coast from Sydney to the Queensland border, dumping up to 75,000 tonnes of dust per hour into the Tasman Sea. The plume travelled about 1500 kilometres to get to the east coast.

Air pollution rose to dangerous levels during the day, with readings of up to 15,400 micrograms per cubic metre of air at one location. A normal reading would be about 10.

Severe weather forecaster Dr Deryn Griffiths of the Bureau of Meteorology says the dust storm started two days ago when 100 kilometre per hour winds whipped up dust from the central region of Australia.

Climatologist Dr Samuel Marx of the University of Queensland says "One of the predictions of the Intergovernmental Panel on Climate Change is that the Australian climate will be more variable and this should probably result in more dust storms," Dr Marx said (ABC Science Online 23.9.09).

Dust storms are not uncommon in Australia, though they are not usually of this magnitude. When the storm originates in agricultural regions the dust carries with it finer, more fertile soil particles, and depletes the fertility of the valuable topsoil.