Drought is a recurring and significant natural phenomenon in Australia, characterized by prolonged periods of below-average rainfall that impact agriculture, water resources, and communities. The Australian Bureau of Meteorology defines drought as rainfall over a period greater than three months being in the lowest decile of historical records for a specific region, emphasizing the relative nature of drought based on typical rainfall patterns and seasonal variations 1. This definition primarily uses rainfall data due to its widespread availability across the country, though it does not account for other factors like evaporation or condensation that affect surface water balance 1.
Historical Context and Frequency
Australia's climate records, dating back to the 1860s, indicate that severe droughts occur on average once every 18 years 1. Some of the most notable droughts include the Federation Drought (mid-1890s to 1902), marked by extreme conditions in 1901-1902 4, the World War II Drought (extending into 1945-1946), which saw rivers like the Murray and Hawkesbury dry up and widespread water restrictions 4, and the Millennium Drought (2001-2009), one of the most severe in recent history, particularly affecting southeast Australia with record-low inflows into the Murray system in 2006 146.
The Millennium Drought, also known as the "Big Dry," was driven by tropical Indian Ocean variability rather than the traditionally assumed Pacific Ocean conditions like El Niño 7. It resulted in Melbourne's water storages dropping from 97.5% in 1996 to just 33% by 2010 4. The drought finally broke in 2010-2011 with the onset of a strong La Niña pattern, bringing record-breaking rains and flooding to the Murray-Darling Basin and other regions 1.
More recently, the Tinderbox Drought (2017-2019) affected southeast Australia, becoming the driest three-year period on record in the region, with cool-season rainfall at half its usual level 5. This drought severely impacted water supplies, agriculture, and ecosystems, and contributed to the devastating Black Summer bushfires, highlighting the connection between drought and fire risk 5. By August 2018, 100% of New South Wales was declared drought-affected, with significant portions of Queensland and other states also impacted by May 2019 1.
Regional Impacts and Variability
Drought affects various regions of Australia differently due to the country's diverse climate. The Murray-Darling Basin, a critical area for food security and home to 2.3 million people, often bears the brunt of drought impacts, with streamflow declining since 1975 and rainfall deficiencies in 2017-2019 being the third lowest on record 156. During the Millennium Drought, southeast Australia missed the equivalent of a full year's rain over 11 years, while the Tinderbox Drought saw river flows cease in many catchments by 2018-2019 15.
Queensland, New South Wales, Victoria, and parts of Western and South Australia have also faced severe drought conditions in recent decades, with record-low rainfall and water deficiencies reported as recently as 2019 19. Tasmania experienced year-round dry conditions during the Millennium Drought, particularly in the warm season 4. Since early 2023, persistent low rainfall has continued to affect much of southern Australia, indicating ongoing challenges 2.
Impacts on Agriculture and Economy
Drought has profound effects on Australia's agricultural sector. During the Millennium Drought, water use in agriculture fell by 37% between 2000/01 and 2004/05, with dairy producers seeing a 5.6% revenue drop in 2004 1. Cotton communities in New South Wales and Queensland were heavily impacted, with production areas reduced by up to 100% in places like Menindee and Biloela 1. The Tinderbox Drought caused winter crop production (wheat and barley) to drop by 43-73% in 2018-2019, and summer irrigated rice production decreased by over 90% in the same period 5. Stock feed scarcity during droughts also poses significant challenges for livestock farmers 1.
Climate Change and Future Outlook
Climate change is exacerbating drought conditions in Australia by increasing temperatures and altering rainfall patterns. Over the past 40 years, average rainfall in New South Wales has decreased, leading to more severe and prolonged droughts 6. Projections indicate that future droughts will be hotter and more intense, as seen in events like the Tinderbox Drought, where climate change played a role in intensifying impacts 5. Research also suggests that natural variability in Australian rainfall could lead to "mega-droughts" lasting 20 years or more, posing significant risks to water security and agriculture 8.
Government and Community Response
The Australian government has implemented measures to mitigate drought impacts, such as the $500 million drought stimulus package in 2013, which included loans, regional council funding, and support for water infrastructure like the Adelaide Desalination Plant 1. State governments, responsible for declaring drought-affected regions, consider factors beyond rainfall in their assessments 1. Despite these efforts, the recurring nature of drought and its increasing severity due to climate change continue to challenge communities, industries, and policymakers.
In summary, drought in Australia is a complex and persistent issue, shaped by historical patterns, regional variability, and emerging climate trends. Its impacts on agriculture, water resources, and ecosystems underscore the need for adaptive strategies to manage future risks.
Citations:
- https://en.wikipedia.org/wiki/Drought_in_Australia
- http://www.bom.gov.au/climate/drought/
- https://earthobservatory.nasa.gov/WorldOfChange/AustraliaNDVI
- http://www.bom.gov.au/climate/drought/knowledge-centre/previous-droughts.shtml
- https://climateextremes.org.au/wp-content/uploads/Australias-tinderbox-drought-Briefing-note.pdf
- https://www.climatechange.environment.nsw.gov.au/impacts-climate-change/weather-and-oceans/drought
- https://ummenhofer.whoi.edu/projects/droughts-and-floods-in-australia/
- https://iceds.anu.edu.au/news-events/news/20-year-%E2%80%98mega-drought%E2%80%99-australia-research-suggests-it%E2%80%99s-happened-%E2%80%93-and-we-should
- https://www.bbc.co.uk/bitesize/guides/zp9bxsg/revision/3
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