World’s Soil Resources

Despite these trends, the Millennium Drought resulted in large dust storms and other wind erosion activity.
Two extreme dust storms hit eastern Australian cities on 23 rd October 2002 and 23 rd September 2009. The ‘Red
Dawn’ dust storm on the 22nd and 23 rd September 2009 was the largest to pass over the coastal city of Sydney
since reliable records began in 1940 (Figure 15.6). Visibility was reduced to 400 m and the maximum hourly
PM 10
concentration was 15 366 μg m -3 – the highest ever recorded for Sydney and possibly for any Australian
capital city. The Australian air quality standard of 50 μg m -3 per 24 h was massively exceeded in suburban
Sydney (1 734 μg m-3) and 150 km to the north in the city of Newcastle (2 426 μg m-3).
Red Dawn was caused by drought and extreme winds. The source of the red dust was primarily the sand
plains of western New South Wales, the sand plains, riverine channels and lakes of the lower Lake Eyre Basin
and the Channel Country of Queensland. The estimate of total suspended particulate sediment lost off the
Australian coast for the 3 000 km long Red Dawn dust storm was 2.54 million tonnes with a plume height of
2 500 m. This is the largest off-continent loss of soil ever reported using measured, as opposed to modelled,
dust concentrations for Australia (Leys et al., 2011). This single event resulted in economic costs of between
AUD $293–A$313 million with most being associated with household cleaning and associated activities. The
dust storm also affected the state of Queensland, but costs there were not included in the study by Tozer and
Leys (2013).
Figure 15.6 MODIS image for 0000 23 September 2009 showing Red Dawn extending from south of Sydney to the Queensland/
NSW border and the PM 10 concentrations measured using Tapered Element Oscillating Microbalances (TEOM) at the same time at
ground stations.
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in the Southwest Pacific