sydney dust storm, sydney bridge dust storm, Australia dust storm
Rob Griffith/AP
A man walks to work past an almost unseen Sydney Harbour Bridge during a dust storm, Sept.
23, 2009.

What Is the Cause and Impact of Australia’s Dust Storm?

September 24, 2009 05:00 PM
by Denis Cummings
Australia’s biggest dust storm in 70 years blanketed Sydney and other parts of the east coast in red dust this week.

NSW and Queensland Covered in Dust

The eastern Australian states of New South Wales and Queensland were hit by a dramatic dust storm Wednesday, dumping millions of tons of red dust on towns and cities.

“Dragging up soil from three states, the plume grew to more than 1500km long and 400km wide; at its peak sweeping up 140,000 tonnes of soil an hour,” reports The Australian. “Overnight the thick, red dust blanketed Sydney, with the city awakening to a deep-red dawn that transformed into an eerie orange glow.”

The BBC collected accounts from Sydney-area residents. One woman said the city looked like Mars, while a man commented, “It was like waking up to see that Armageddon is upon us.”

The storm, the biggest in Australia in 70 years, according to the weather bureau, brought cities such as Sydney and Brisbane to a standstill. Residents were advised to remain indoors as dust levels in the air reached dangerous levels. The storm has since moved out to sea, leaving eastern Australia with a massive clean-up job.

Analysis: Cause and impact of the dust storm

Dust storms are common in Australia, but they are usually confined to the sparsely inhabited interior. Droughts can cause the storms to reach coastal areas and cause disaster.

The Australian Bureau of Meteorology recounts the three greatest dust storms of the 20th century, including the Melbourne dust storm of February 1983. The last major dust storm to hit the coast occurred in 2002, when between 3.3 million and 4.8 million metric tons of dust hit New South Wales and Queensland.

Australia is in the midst of one of its worst-ever droughts, caused in large part by the El Nino weather pattern that brings dry weather to the Australian continent, already the driest inhabited continent. Weather has been hotter in recent years, as the recently completed winter was the hottest on record.

John Leys, a scientist with the Department of Environment and Climate Change, said that Australia has had droughts for eight straight years and an increase in dust storms the last seven years. New South Wales is having “something like 10 times more dust storms than normal,” he told the Sydney Morning Herald.

When the weather is dry, topsoil becomes loosened and is dragged off by the wind. In this storm, 100-kilometer winds carried dust from Central Australia, likely the Lake Eyre Basin, east to the coast.

Australian scientists were unsure if global warming is to blame for the dust storm. Nigel Tapper, head of geography and environmental science at Monash University, explained to the Morning Herald, “We've always had dust storms. … So to that extent you can't say that it's related to greenhouse-induced climate change in the last few years.” But Tapper did say that the drop in rainfall could be attributed to global climate change.

The storm causes economic damage in cities due to lost productivity and clean up. Mark Goodsell of Australian Industry Group estimated that Sydney alone lost “tens of millions of dollars” The damage for farms will be far more severe, as the stripping of topsoil will lower crop output. Reuters reports that the estimate for the New South Wales wheat crop has been reduced from 7.5 million to 6.5 million metric tons.

Background: Science of dust storms

NASA scientists Ron Miller and Ina Tegen explain how dust storms are caused and how they affect the environment.

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