Mary Voice¹ and Craig Pearson²

1. National Climate Centre, Bureau of Meteorology, GPO Box 1289K, Melbourne 3001.

2. Bureau of Rural Sciences, Agriculture, Fisheries and Forestry Australia, PO Box E11, ACT 2604.

When Captain James Cook sailed into Botany Bay in the autumn of 1770, he saw green meadows and running water. Based on his reports, England dispatched a Fleet, with spades and hoes but no plough on board, expecting that the convicts could live off the land (Blainey, 1980). Such was the lack of understanding of what drought could do in Australia. El Niño of course, was unheard of by Europeans about to settle an ENSO dominated land.

What is considered a drought in England or Japan may be thought of as a minor dry spell in Australia. El Niño, a major cause of drought in the eastern half of Australia, also has large impacts in other parts of the world, (Allan, 1996), however Australia was the first country to introduce regular seasonal forecasts based on El Niño and the Southern Oscillation (Bureau of Meteorology, 1988).

Australia embarked on nationhood and the twentieth century in the midst of droughts linked partly to El Niño, (Fig. 1). The 1895-1903 Federation drought is one of the worst on record. It marked a new phase in the climate of south-eastern Australia, where there had been many boom years since the 1850s. The number of sheep in Australia almost halved, from 106 million in 1891 to 54 million in 1902. The 1902 loss in wool revenue was estimated at 2.7 million pounds (about AUS$250m ). Cattle numbers declined by 40 per cent, so that most working families ceased to eat good beef. Dust storms were frequent. In south-eastern Australia the area of ground ploughed for wheat in 1900 was almost six times that ploughed in 1866, and much of that tilled soil, no longer held by moisture or grass, was blown away. On 21 November 1902 Melbourne was coated in a dust-storm from the interior, just like the dust-storm of February 8^th 1983, near the end of the severe 1982-83 El Niño.

The Australian historian Professor G. Blainey argues that the fluctuations in climate were one of the vital causes of the long prosperity of the forty years to 1890 and of the leaner decades which followed. The promise of irrigation and water storages kept optimism alive in the early decades of the 20^th century.

The 1965-67 drought resulted in a 40 per cent drop in the wheat harvest, a loss of 20 million sheep, and a decrease in farm income of $300-500 million. There was a chain reaction to other industries with heavy losses being suffered by manufacturers of farm machinery, and the railways. Water rationing had to be introduced in irrigation areas.

During the 1982-83 El Niño, Victoria’s 1982 cereal crop was the worst since 1944, when dislocation due to the Second World War and two years of severe dry conditions had caused a very low yield. The Commonwealth Government made over AUS$320m ($680m in today’s terms) available for drought relief.

Irrespective of improved economic and agricultural skills, the vulnerability of the land to drought has decreased only slightly. Over much of Australia, loose sandy soils are still exposed to wind erosion during drought. The floods which often follow can then be equally as damaging to the unstable unprotected topsoil.

By the end of the twentieth century, most Australians knew of El Niño, and many could identify the broad scale impacts on Australia. Far fewer knew about the counter part La Niña, nor that much of our agricultural wealth stemmed from the "good" years brought by La Niña. As the two maps show, the Southern Oscillation and its associated extremes of El Niño and La Niña brings with it a marked climate oscillation over Australia, (Fig. 2). Note that the footprints of El Niño and La Niña are not identical - La Niña is not the exact opposite of El Niño. But they are rather close.

Rural productivity, especially in Queensland and New South Wales, is linked to the behaviour of the Southern Oscillation. Negative phases in the oscillation (drier periods) tend to have been linked with reduced wheat crops, and vice versa. Even more telling, the net value of all of Australia’s rural production has taken a marked dip in most of the major El Niños of the past twenty years (Fig. 3). The balance sheet for living in a Southern Oscillation dominated land is shown in the box.

Fig. 4 shows grain yield for NSW over a century with "failed rainfall years", as determined by a simple rainfall indicator, marked. Climate variability is one of the major causes of yield variability. Further examples of impacts of particular droughts and wet phases and net farm economy assessments will be given in the conference presentation.

The water storages a region needs depend upon the reliability of the rainfall, population density and agricultural water use. Judgements must be made about the cost effectiveness of building large dams to cope with very rare events. In Australia, El Niño’s impact makes this a difficult call. A century ago, irrigation and water storage were seen as the solution to Australia’s aridity. However, at the start of the 21^st century, Australia’s water resources are already heavily used (Fig 5).

Rural communities need the best climate advice to help them protect and sustain ecological resources in the face of climate extremes. Improved understanding of climate variability, and application of appropriate management techniques, will be crucial to achieving sustainable development goals in the 21^st century. Sustainable development requires improved management in all climate ranges, especially during climate extremes, which bring the greatest risk of environmental degradation. Improved climate understanding and forecast skill may increase the range of low-risk conditions, and enhance our capacity to better manage high risk periods.

1. Wet and dry decades in eastern Australia, major drought years and big El Niño and la Niña episodes. (Annual rainfall averaged over eastern Australia is also shown).

2. Net value of rural production for all Australian agriculture. Even though agricultural activity spans the continent, including areas where El Niño and la Niña impacts are weak, the big El Niño episodes still put a dent in the national economy, and the strong la Niña years are usually the better agricultural years.

5. Pushing the limits of water use: the percentage use of surface water in Australia in an average climatic year.

Allan, R. 1996: El Niño Southern Oscillation and Climate Variability: CSIRO Australia 1996.

Blainey, G. 1980: A land half won. MacMillan Co.

Bureau of Meteorology, 1988: Seasonal Outlooks (Based on El Niño/southern Oscillation (ENSO) Relationships, National Climate Centre, August 1988.