Barrie Hunt, a researcher with government science agency CSIRO, dismissed suggestions that global warming, believed to be caused by carbon emissions, is responsible for the "Big Dry" gripping much of south-eastern Australia.

"It is very, very highly likely that what we are seeing at the moment is natural climatic variability," Hunt told the Australian newspaper.

After studying a CSIRO model of Australia's natural climate patterns over the past 10,000 years, Hunt said the current drought, whose severity has led some scientists to label it a once in a millennium event, was by no means unique.

He said historical data -- which used air pressure, temperature, wind and rainfall information -- put current conditions into perspective, revealing 30 periods of drought lasting longer than eight years in the past ten millenia.

"The longest sequence was 14 years in Queensland-New South Wales, 11 in the south-east and 10 in the south-west."

He said that each of those significant dry spells occurred at random times and had an unpredictable duration.

For example, the Queensland-NSW area went 800 years without a drought longer than eight years, "but there is another period of 462 years where you get five of these", he said.

"When people talk about it as a 1,000-year drought, they haven't got the information. They don't understand that according to natural variability we could get another one in 50 years or it might be another 800 years, and there's no way of predicting it," Hunt said.

However, he did not deny global warming risked raising Austarlia's temperatures, which CSIRO predicts will rise up to two degrees Celsius (3.6 Fahrenheit) by 2030 and six degrees Celsius (10.8 Fahrenheit) by 2070.

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