Drought in Australia

Editor: Justin Healey ISBN 978 1 920801 29 8 Year 2005 Price: $19.95		Drought in Australia Volume 220, Issues in Society Australia is the driest continent, and has one of the most variable rainfall climates in the world. Our current drought is the worst on record. This book explores the causes, impacts and history of drought in Australia; how drought is defined and measured; climate change in relation to changed rainfall conditions; water use; drought assistance measures; and practical ways in which farmers and their families can plan for the extreme impacts of future droughts. Chapter 1 Drought in Australia Living with drought; Defining drought; Drought hazards and disasters; A history of drought in Australia; It’s official: big dry was worst on record; Just another drought?; Global warming contributes to Australia’s worst drought; More rain, but in all the wrong places. Chapter 2 Coping with Drought Drought assistance; Australia’s National Drought Policy; Frequently asked questions on exceptional circumstances; Latest drought hits agriculture hard; Dry away those tears; FATE and drought; Trickle should be a torrent; Planning for drought; Drought hints; Planning for future droughts; Coping with the social impact of drought; Tool kit for getting through the drought. Glossary; Facts and Figures; Additional Resources; Index

		FAST FACTS from this volume
Meteorologists monitor the extent and severity of drought in terms of rainfall deficiencies. Agriculturalists rate the impact on primary industries, hydrologists compare ground water levels, and sociologists define it on social expectations and perception. During climate extremes, whether droughts or flooding rains, those on the land feel it most. Agriculture suffers first and most severely – yet eventually everyone feels the impact. Drought disrupts cropping programs, reduces breeding stock, and threatens permanent erosion of the capital and resource base of farming enterprises. Declining productivity affects rural Australia and the national economy. Research indicates that severe drought affects some part of Australia about once every 18 years. This does not indicate that severe drought regularly and predictably recurs every 18 years; intervals between severe droughts have varied from four to 38 years. We have long historical rainfall records to give a clearer picture of what is ‘normal’ for an area, and how much variation might be expected. There is little chance that all Australia could be in drought at the same time. Some droughts are long-lived; some are short and intense, causing significant damage. Some can be localised while other parts of the country enjoy bountiful rain. Some regional droughts are not related to El Niño events, and are therefore harder to forecast. The Australian climate of 2002 was characterised by dry and warm conditions. It was the fourth driest year on record, while maximum temperatures across the continent were the warmest on record. Droughts and higher than average temperatures are often linked. One of the measurable impacts of drought is a reduction in water storage levels. Changes in water storage levels can lead to the introduction of water restrictions, which limit the volume and way users can utilise water, especially in urban settlements. In Australia, even when our weather is not affected by global weather shifts, our rainfall pattern is among the most variable in the world. This is due to our size, location, geography and climatic range, and means many areas are subject to the regular threat of drought. The causes of drought originate with the fluctuations in global climate, which are a combination of the systems of atmosphere, oceans, ice masses and biosphere. The most widely known recurring climatic irregularity that develops every few years is known as the El Niño phenomenon. This is a name given to unusually warm ocean currents off the equatorial Pacific coast of South America. El Niño is actually an extreme swing in a recurring air pressure shift across the Pacific Ocean called the Southern Oscillation. Many droughts affecting eastern and northern Australia are a direct result of a strong swing in the Southern Oscillation, accompanied by cooler than normal ocean currents off northern Australia. Long-term averages indicate that in terms of rainfall, out of every 10 years, we have about 3 good years, 4 average years, and 3 bad ones. Research also reveals that very severe drought affects some part of Australia every 18 years approximately. Drought intensity is a measure of rainfall deficiency over three months. For a particular region, between 5 and 10% above the lowest on record is rated as serious and less than 5% above lowest on record is rated as severe. Occasionally, droughts last for 7 or 8 years, but within that period the severity may fluctuate with spells of rainfall, although still well below average. Other droughts are shorter (one or two years) but more intense with very little rain recorded. It is unlikely that the entire country could suffer drought at the same time. Some droughts can be localised with other relatively close areas receiving normal rainfall. Often regional droughts are not related to El Niño events, so they are even more difficult to predict. The effects of drought firstly impact on agriculture, causing reduction or loss of water supplies, crop failures and livestock losses. They can also lead to environmental damage through vegetation and wildlife loss, erosion, and toxic algal blooms in depleted dams, rivers and lakes. In the country or city we may face severe water restrictions and will be affected by rising food prices, reduced supply and in extreme cases in some countries, devastating famine (e.g. China in 1877-78 when 9.5 million people starved to death). Other drought-related hazards in Australia are heatwaves, dust storms and bushfires, all of which can impact on communities. Over much of the country, droughts can extend over several years, relieved only by brief, transitory rains. Indeed, probably the most damaging type of drought is when one or two very dry years follow several years of generally below average rainfall. Global warming is a reality. CSIRO modelling studies have projected increases in Australian temperatures of between 1ºC and 6ºC by 2070, much greater than the increases over the past 50 years. These temperature increases would lead to even greater evaporation and water stress during future droughts. CSIRO has also projected up to a 45% decrease in stream flow in the Murray-Darling Basin by 2070 and a marked increase in the frequency of extreme droughts under global warming conditions. It is difficult to assess whether droughts in Australia (as defined by rainfall deficiencies) are progressively getting worse. This is because rainfall patterns in Australia are so variable that we need a much longer climate record than we presently have in order to discern any meaningful trends. What is clear is that the average temperature in Australia has been steadily rising over the past 50 years.

Meteorologists monitor the extent and severity of drought in terms of rainfall deficiencies. Agriculturalists rate the impact on primary industries, hydrologists compare ground water levels, and sociologists define it on social expectations and perception.
During climate extremes, whether droughts or flooding rains, those on the land feel it most. Agriculture suffers first and most severely – yet eventually everyone feels the impact. Drought disrupts cropping programs, reduces breeding stock, and threatens permanent erosion of the capital and resource base of farming enterprises. Declining productivity affects rural Australia and the national economy.
Research indicates that severe drought affects some part of Australia about once every 18 years. This does not indicate that severe drought regularly and predictably recurs every 18 years; intervals between severe droughts have varied from four to 38 years. We have long historical rainfall records to give a clearer picture of what is ‘normal’ for an area, and how much variation might be expected.
There is little chance that all Australia could be in drought at the same time. Some droughts are long-lived; some are short and intense, causing significant damage. Some can be localised while other parts of the country enjoy bountiful rain. Some regional droughts are not related to El Niño events, and are therefore harder to forecast.
The Australian climate of 2002 was characterised by dry and warm conditions. It was the fourth driest year on record, while maximum temperatures across the continent were the warmest on record. Droughts and higher than average temperatures are often linked.
One of the measurable impacts of drought is a reduction in water storage levels. Changes in water storage levels can lead to the introduction of water restrictions, which limit the volume and way users can utilise water, especially in urban settlements.
In Australia, even when our weather is not affected by global weather shifts, our rainfall pattern is among the most variable in the world. This is due to our size, location, geography and climatic range, and means many areas are subject to the regular threat of drought.
The causes of drought originate with the fluctuations in global climate, which are a combination of the systems of atmosphere, oceans, ice masses and biosphere. The most widely known recurring climatic irregularity that develops every few years is known as the El Niño phenomenon. This is a name given to unusually warm ocean currents off the equatorial Pacific coast of South America. El Niño is actually an extreme swing in a recurring air pressure shift across the Pacific Ocean called the Southern Oscillation.
Many droughts affecting eastern and northern Australia are a direct result of a strong swing in the Southern Oscillation, accompanied by cooler than normal ocean currents off northern Australia.
Long-term averages indicate that in terms of rainfall, out of every 10 years, we have about 3 good years, 4 average years, and 3 bad ones. Research also reveals that very severe drought affects some part of Australia every 18 years approximately.
Drought intensity is a measure of rainfall deficiency over three months. For a particular region, between 5 and 10% above the lowest on record is rated as serious and less than 5% above lowest on record is rated as severe. Occasionally, droughts last for 7 or 8 years, but within that period the severity may fluctuate with spells of rainfall, although still well below average. Other droughts are shorter (one or two years) but more intense with very little rain recorded.
It is unlikely that the entire country could suffer drought at the same time. Some droughts can be localised with other relatively close areas receiving normal rainfall. Often regional droughts are not related to El Niño events, so they are even more difficult to predict.
The effects of drought firstly impact on agriculture, causing reduction or loss of water supplies, crop failures and livestock losses. They can also lead to environmental damage through vegetation and wildlife loss, erosion, and toxic algal blooms in depleted dams, rivers and lakes.
In the country or city we may face severe water restrictions and will be affected by rising food prices, reduced supply and in extreme cases in some countries, devastating famine (e.g. China in 1877-78 when 9.5 million people starved to death). Other drought-related hazards in Australia are heatwaves, dust storms and bushfires, all of which can impact on communities.
Over much of the country, droughts can extend over several years, relieved only by brief, transitory rains. Indeed, probably the most damaging type of drought is when one or two very dry years follow several years of generally below average rainfall.
Global warming is a reality. CSIRO modelling studies have projected increases in Australian temperatures of between 1ºC and 6ºC by 2070, much greater than the increases over the past 50 years. These temperature increases would lead to even greater evaporation and water stress during future droughts.
CSIRO has also projected up to a 45% decrease in stream flow in the Murray-Darling Basin by 2070 and a marked increase in the frequency of extreme droughts under global warming conditions.
It is difficult to assess whether droughts in Australia (as defined by rainfall deficiencies) are progressively getting worse. This is because rainfall patterns in Australia are so variable that we need a much longer climate record than we presently have in order to discern any meaningful trends. What is clear is that the average temperature in Australia has been steadily rising over the past 50 years.