- They happen worldwide and are becoming more common, including in Australia, due to global warming.
- Flash droughts can occur anywhere and at any time of the year.
- Last year, a flash drought hit the Upper Hunter region of New South Wales, roughly 300 kilometres north-west of Sydney.
- Flash droughts are set to get more common as the world heats up.
What makes a flash drought different?
- The latter result from extended drops in rainfall, such as the drought affecting parts of southwest Western Australia due to the much shortened winter wet season last year.
- Flash droughts develop when sudden large drops in rainfall coincide with above-average temperatures.
- That year saw flash droughts appear across the northern hemisphere, such as the megadrought affecting China’s Yangtze river basin and Spain.
- The flash drought greatly affected agricultural production in the Upper Hunter region, due to the region’s reliance on water from rivers.
- Flash droughts are characterised by abrupt periods of low rainfall leading to rapid drought onset, particularly when accompanied by above-average temperatures.
The Upper Hunter drought is part of a trend
Flash droughts will be more common in the future. That’s because higher temperatures will more often coincide with dry conditions, as relative humidity falls across many parts of Australia and globally. Climate change is linked to shorter, heavier bursts of rain followed by longer periods of little rainfall.
- The much lower rainfall continued until November in the Upper Hunter.
- While flash droughts occurred in other parts of south-east Australia, we focused on the Upper Hunter as it remained in drought the longest.
What were the climate drivers of this drought?
- We used machine-learning techniques to identify the key climate drivers of the drought.
- Combined, the impact of global warming with the three climate drivers made rainfall much more variable.
Victoria, too, fits the global warming pattern
- The flash drought followed very high January rainfall (top 5% of records) dropping rapidly to very low rainfall (bottom 5%) in February and March.
- The pattern of the 2024 flash drought in Victoria typifies the increasing trend under global warming of long dry periods, interspersed by short, heavy rainfall events.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.