Reuters 23 Sep 09;
(Reuters) - A dust storm swept across eastern Australia and blanketed Sydney on Wednesday, disrupting transport, placing health authorities on alert for widespread respiratory illness and stripping thousands of tonnes of topsoil off Australia's main farmlands.
Following are answers to questions about the storm.
WHAT CAUSED THE DUST STORM?
During winter in Australia low pressure storms are generated in the Indian and Southern Oceans, whipping up huge seas and creating severe cold fronts which sweep across southern and eastern Australia. A severe thunderstorm with 100 km per hour (60 miles per hour) plus winds formed in South Australia state on Monday and began whipping up dust from drought-hit outback lands. As vegetation gets dried off the topsoil is loosened, and it easily blows away. As the dust storm traveled into the eastern seaboard state of New South Wales, one of the worst hit by drought, it grew in size and by Wednesday morning was affecting most of NSW, the fifth biggest state or territory representing 10 percent of the island continent, and had descended on Sydney like a thick blanket.
IS THE DUST STORM LINKED TO CLIMATE CHANGE?
Weather scientists are reluctant to directly link climate change with extreme weather events such as storms and droughts, saying these fluctuate according to atmospheric conditions, but green groups link the two in their calls for action to fight climate change.
Dust storms in Australia, the world's driest inhabited continent with a vast desert-like outback interior, are not uncommon. Central and eastern Australia is a major global source of atmospheric dust, say weather experts. But dust storms are usually restricted to the inland of Australia. Occasionally, during widespread drought they can affect coastal areas. Australia is battling one of its worst droughts and weather officials say an El Nino is slowly developing in the Pacific which will mean drier conditions for Australia's eastern states.
Before the Sydney dust storm, one of the most spectacular storms swept across Melbourne in February 1983, late in the severe El Nino drought of 1982/83. The extended dry period of the 1930s and 1940s generated many severe dust storms, culminating in the summer of 1944/45 when on several occasions dust in Adelaide was so thick that street lighting had to be turned on. Satellite images showed a 2002 dust storm, about 1,500 km (930 miles) long by 400 km (250 miles) wide and 2.5 km (1.5 miles) high, stretching across New South Wales and Queensland states.
WHAT IS THE ECONOMIC AND ENVIRONMENTAL IMPACT OF DUST STORMS?
While dust storms may cause temporary disruptions to towns and cities, by far the worst effect is the stripping of topsoil from Australia's farmlands. In the late 1970s and early 1980s severe drought in Australia saw dust storms strip millions of dollars worth of topsoil, causing massive crop and stock losses, according to the country's Emergency Management Authority. Crop analysts say the current dust storm is unlikely to have an immediate impact on wheat crops which are already struggling with dry conditions. Harvesting starts next month in NSW, the country's second largest grain producing state. Australian Crop Forecasters estimates the NSW wheat crop will be down by about one million tonnes to around 6.5 million tonnes.
WILL THERE BE MORE DUST STORMS?
Australian weather officials are warning of another severe storm to sweep across the southern and eastern parts of the country on Thursday and Friday. Australia's main farmlands are located in the eastern part of the country. The next storm could again whip up a dust storm, cause damage with gale-force winds and send temperatures plummeting and dump snow on Australia's alpine region. If El Nino weather conditions continue in the western Pacific then Australia's dry conditions and then more dust storms can be expected, but whether they remain confined to inland or outback regions or sweep across farmlands and reach more populated centers remains unknown.
(Reporting by Michael Perry; Editing by Dean Yates)
Dust storm blankets Sydney as drought bites
Michael Perry, Reuters 23 Sep 09;
SYDNEY (Reuters) - A huge outback dust storm swept eastern Australia and blanketed Sydney on Wednesday, disrupting transport, forcing people indoors and stripping thousands of tonnes of valuable farmland topsoil.
The dust blacked out the outback town of Broken Hill on Tuesday, forcing a zinc mine to shut down, and swept 1,167 km (725 miles) east to shroud Sydney in a red glow on Wednesday.
By noon on Wednesday the storm, carrying an estimated 5 million tonnes of dust, had spread to the southern part of Australia's tropical state of Queensland.
Dust storms in Australia are not uncommon but are usually restricted to the inland. Occasionally, during widespread drought, dust storms reach coastal areas. Australia is the driest inhabited continent and only Antarctica is drier.
Australia is battling one of its worst droughts and weather officials say an El Nino is slowly developing in the Pacific which will mean drier conditions for eastern states.
The country is one of the most vulnerable nations to climate change, but also the world's biggest greenhouse gas emitter per capita as it relies on coal-fired power stations for the bulk of its electricity.
Scientists are reluctant to directly link climate change with extreme weather events such as storms and drought, saying these fluctuate according to atmospheric conditions, but green groups link the two in their calls for action.
International flights were diverted from Sydney, ferries on Sydney Harbor were suspended and motorists warned to take care on roads because of poor visibility. The dust set off smoke alarms in some buildings in Sydney's central business district and halted construction.
Health authorities urged people to stay indoors, warning the storm was likely to continue into Thursday. More than 200 people called emergency services with breathing difficulties. The official air quality index for New South Wales recorded pollutant levels as high as 4,164 in Sydney. A level above 200 is hazardous. (here)
"People at risk are children, elderly, pregnant women, people with heart and lung diseases. Dust particles can increase the risk of people with these conditions becoming unwell," said Wayne Smith from the New South Wales state health department.
"EARTH, WIND AND FIRE"
The Bureau of Meteorology said a big cold front in New South Wales caused severe thunderstorms and gale-force winds, which whipped up the dust from the inland and spread it across Australia's most populous state. Winds of more than 100 km per hour also fanned bushfires in the state.
"This is unprecedented. We are seeing earth, wind and fire together," said Dick Whitaker from The Weather Channel.
New South Wales recently cut the state's 2009/10 wheat crop estimate by a fifth because of dry weather.
Sydney residents told local radio that they woke to scenes from a Hollywood apocalyptic movie, while many contacted emergency services fearing a big bushfire in the city.
Karen from Sydney's inner western suburb of Dulwich Hill said she woke up to find the red dust had covered her floors and birds had been blown out of their nests.
"It did feel like Armageddon because when I was in the kitchen looking out the skylight, there was this red, red glow coming through," Karen told Australian radio.
The blanket of dust affected most of New South Wales, the fifth-biggest state or territory representing 10 percent of the continent, and southern parts of Queensland state.
The dust storms stripped valuable topsoil from primary eastern farmlands. At one stage up to 75,000 tonnes of dust per hour was blown across Sydney and dumped in the Pacific Ocean, but the exact amount of dust dumped on Sydney was still being calculated.
"We've got a combination of factors which have been building for 10 months already -- floods, droughts and strong winds," said Craig Strong from DustWatch at Griffith University in Queensland.
"Add to these factors the prevailing drought conditions that reduce the vegetation cover and the soil surface is at its most vulnerable to wind erosion."
But crop analysts said the storm is unlikely to have an immediate impact on wheat crops, in the country's second-largest grain producing state, due to be harvested next month.
Further cold fronts are expected later in the week and could again whip up more dust storms, said weather officials. (Editing by Jan Dahinten)
Huge dust storm blankets eastern Australia
Talek Harris Yahoo News 23 Sep 09;
SYDNEY (AFP) – The worst dust storm in decades hit Australia on Wednesday, blanketing Sydney in red dust, and snarling up the transport system as earthquakes, giant hailstones and even a tornado swept the east of the country.
Gale-force winds dumped thousands of tonnes of red desert dust on Australia's biggest city, shrouding it in an eerie orange haze and coating the iconic Sydney Opera House in a fine layer of powder.
The storm, reportedly the most serious since the 1940s, then spread 600 kilometres (375 miles) up the coast to Queensland and could even hit New Zealand, some 4,000 kilometres away, experts said.
Dust covered most of New South Wales, Australia's most populous state, pushing air pollution to record levels and depositing about 75,000 tonnes of powder in the Tasman Sea every hour.
"Dust storms like this occur quite regularly but they rarely travel this far east and come through Sydney," said John Leys, principal research scientist with New South Wales' Department of Climate Change and Water.
Sydney residents wore face masks and covered their mouths with scarves as they travelled to work under hazy skies. Traffic was bumper-to-bumper on major highways.
Air transport was severely disrupted with long delays at Sydney airport and many international flights diverted to Melbourne and Brisbane.
Flag-carrier Qantas urged passengers to cancel any non-urgent travel, while budget offshoot Jetstar offered free flight rescheduling and refunds.
"We encourage any passengers with non-essential travel arrangements to reconsider their travel plans for the day," Qantas said in a statement.
Sydney Ferries suspended harbour services and police warned drivers to take extra care in poor visibility. Ambulance workers reported a sudden spike in respiratory problems.
"We have already seen an increase in calls to people suffering from asthma and other respiratory problems," New South Wales Ambulance Service said in a statement.
Australia, in the grip of a decade-long drought, is emerging from an abnormally hot southern hemisphere winter including the hottest August on record.
Elsewhere in New South Wales, hail stones "the size of cricket balls" smashed windows as thunderstorms and gale-force winds lashed the state late on Tuesday.
"We've had reports of cars with both their front and rear windscreens smashed," an official from the State Emergency Service said.
Further north, Queensland imposed a ban on lighting fires across large parts of the state a day after a dozen bush blazes sprang up following a spell of hot, dry weather.
Tough water restrictions there are to be temporarily set aside to allow people to wash dust off their cars, homes and business premises, the Australian AAP news agency reported.
"This has been an extraordinary event with many parts of the region now caked in dust," Queensland Water Commission acting chief executive Daniel Spiller was quoted by the agency as saying.
Victoria state was on alert for flash floods as heavy rains fell, following a pair of minor earthquakes on Tuesday. The 3.0- and 2.6-magnitude tremors did not cause any damage, officials said.
Police in southwestern New South Wales, bordering Victoria, reported bizarre conditions on Tuesday as dark red skies thick with dust cut visibility to just two to three metres in some areas.
"I've never seen anything like it in all my life -- and I grew up here," a police officer at the town of Broken Hill told AAP.
"It was darker than night-time, and lasted for about half an hour. You couldn't even see the street lights."
