When catastrophic wildfires capture global headlines, such as the unprecedented blazes sweeping through southern Europe this summer or the devastating 2019–20 “Black Summer” in Australia, they are almost always preceded by severe drought. Dry vegetation and parched landscapes are necessary ingredients for infernos.
But not all droughts are created equal – the way a drought evolves can drastically alter how a fire behaves once it ignites. As global temperatures rise, a new and dangerous phenomenon is becoming increasingly common: the “flash drought”.
Unlike standard droughts, which take place over months or years, flash droughts are rapidly occurring dry spells, driven by intense heat and unusually low humidity. They suck moisture out of the landscape at an alarming rate.
While scientists know standard droughts increase fire risks, a critical question has remained unanswered: do flash droughts further increase this risk, and what happens when these two drought types collide?
Our latest research mapped two decades of global satellite data to answer this question. We found when landscapes transition from a prolonged standard drought into a rapid flash drought – or when the two overlap – they create a “hyper-flammable” state. This acts as a massive fire accelerant; they spread faster, last longer and grow significantly larger than other wildfires.
How hyper-flammability works
To understand why this happens, we have to look at how different droughts affect the environment. The major difference is the speed at which they occur.
A standard drought acts like a slow, relentless oven. Over months, it gradually dries out vegetation and severely reduces soil moisture, leaving a dry environment primed to burn.
A flash drought, on the other hand, is like hitting the landscape with a high-powered hairdryer. The atmospheric dryness rapidly increases, characterised by extreme heat and low humidity, and quickly depletes remaining soil moisture.
When a standard drought turns into a flash drought, the effects don’t just add up; they multiply. Combined, they cause the fire danger to skyrocket, setting the perfect stage for fast-spreading and intense wildfires. Short-lived weather anomalies such as flash droughts generate disproportionately severe and extreme fires.
Tracking two decades of global fires
To uncover this pattern, we analysed global drought and satellite-based fire data sets from 2002 to 2021. Global wildfires were categorised into four distinct groups: fires occurring under normal (no drought) conditions; fires occurring during flash droughts; fires occurring during isolated standard droughts; and fires occurring where the two drought types overlapped or followed one another.
Across every single fire metric we measured, including speed, size, duration and spread, fires burning under combined drought conditions were the most extreme. The median size of these fires was 65% larger than fires in normal conditions, and 21% larger than those occurring during standard droughts alone. They spread 35% faster and burned 19% longer.
We also discovered that regions experiencing combined drought conditions endured significantly longer dry spells before a fire actually started. On average, 72 days passed between the onset of a combined drought and the start of a fire. This compared with only 17 days for flash droughts and 56 days for standard droughts. This prolonged period allows severe dryness to develop before fires start.
Global fire hotspots
While fires that follow standard droughts are widespread across the globe’s arid and semi-arid zones, we found fires following flash droughts and, particularly, combined droughts, clustered in distinct geographic hotspots.
The most extreme are heavily concentrated in highly vulnerable communities of plants and animals, including the savannas of South America and Africa, northern Australia, and the western United States.
These regions are highly susceptible to rapid-onset heat and moisture stress, making them ground zero for compounding climate extremes. The presence of both slow-moving and flash droughts causes the most extreme fire behaviour, thus amplifying the fire’s intensity.
Rethinking wildfire preparation
As the climate continues to heat up, the rate of evaporation increases worldwide. This means the frequency and extent of combined droughts are likely to increase across fire-prone regions around the world.
Crucially, we must stop viewing droughts simply as a static state of reduced moisture. Instead, we must recognise them as evolving processes, in which the shift from one type of drought to another can fundamentally change wildfire severity.
Unfortunately, many current global drought and fire monitoring systems emphasise real-time conditions, or look at drought severity as an aggregated whole. To better protect communities and nature, these systems urgently need to integrate information on how droughts evolve. This would enable us to better detect emerging hyper-flammable landscapes before the first spark.
Abhirup Dikshit receives funding from the Australian Research Council.
Jason Evans receives funding from the Australian Research Council.
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The Australian government this week announced plans to construct a new large-scale oil refinery in Western Australia. If approved, it would be the first refinery to be built since the 1960s.
The federal government initially touted the idea of a government-backed oil refinery in April. In the months since, Australians have grappled with surging petrol prices triggered by the prolonged US-Iran war.
The federal government, with Western Australia, has now announced it will jointly fund a A$4 million pre-feasibility study into a proposed large-scale oil refinery. This study will assess if Australia needs a new large-scale refinery and, if so, where it should go and how it should be operated.
This announcement raises several crucial questions: what is the government proposing? Could it shore up Australia’s fuel supplies? And what does it mean for emissions reduction?
A country exposed
The prolonged US-Iran war has revealed just how vulnerable Australia’s liquid fuel supply is.
Two decades ago, Australia had eight oil refineries. That number has dwindled to two – Queensland’s Ampol refinery and Victoria’s Viva energy plant – as ageing infrastructure and rising costs made these facilities uneconomical. For these reasons the Kwinana refinery – formerly Australia’s largest oil refinery located just south of Perth – shut down in 2021.
These closures have made Australia extremely reliant on liquid fossil fuel imports. We currently import 90% of our petrol, jet fuel and diesel from Asia. The remaining 10% of liquid fuels come from Australia’s two remaining refineries. Both refineries are remnants of the oil boom of the 1950s and 60s, when several major oil companies scrambled to take advantage of newly discovered Bass Strait oil and a wave of government investment.
But our research shows Australia needed more refineries, even before the US-Iran conflict erupted. This was made clear by the refinery fire at Victoria’s Viva plant in April, which temporarily halted domestic production. However, several factors – including high construction costs, declining domestic crude oil supply and intense competition from Asian mega-refineries – have stopped Australia from building new plants.
The $4 million pre-feasibility study will determine where a new refinery should be built. The government has identified Western Australia as the most suitable state. But it is yet to confirm exactly where the proposed refinery will go.
There are two main contenders. One is Kwinana, which is close to Perth’s urban energy market and the now-closed Kwinana refinery. However, it’s unlikely to win out given the former refinery site is earmarked for redevelopment as a biofuels hub.
The other option is Karratha in WA’s Pilbara region. This fast-growing city is suitable for two reasons. It’s close to the North West Shelf project, Australia’s largest operating oil and gas development. It’s also where Perdaman, the company slated to construct the proposed refinery, is already building a $6.5 billion fertiliser plant.
For the proposed refinery to work, it requires a steady supply of oil.
Australia produces around 250,000 barrels of light crude oil each day. Most of this oil is exported to Asian refineries, and returns to Australia as liquid fuel.
WA’s northwest shelf region primarily produces gas. This means it offers only limited feedstock – the raw or processed oil needed to make fuels, chemicals or plastics – for a proposed refinery.
It’s possible to redirect northwest shelf oil so it goes to the refinery, instead of being exported. However, Australia’s existing export contracts could make this difficult, and negotiations may be necessary.
An alternative oil source is the Bass Strait. In 2026, the federal government started showing interest in Victoria’s Gippsland basin and the Bass basin, in the waters between Victoria’s southern tip and northern Tasmania. The government is now exploring these basins as potential offshore petroleum sites to gauge if there’s appetite for future exploration licences among petroleum companies.
If approved, it would take between five to ten years to build a facility of this size, subject to whether approvals are fast-tracked.
If the proposal does go ahead, a new refinery would provide much-needed liquid fuel security in a world of surging energy prices and volatile oil supplies. Depending on its size, the new refinery may exceed the former Kwinana refinery’s daily production of 146,000 barrels of oil. This would reduce Australia’s reliance on imported fuel, and ease the petrol pump pain of all Australians.
But it also begs the question, should Australia keep producing conventional liquid fuels? Our rapidly warming climate demands we shift away from these polluting energy sources. Low-carbon biofuels – renewable fuels made from plants, algae or animal waste – may be one alternative.
Another possible path forward is designing any new refineries so that biofuels can be produced alongside traditional liquid fuels. However, this must be viable from both an environmental and fuel security perspective, and should be a focus of the government’s pre-feasibility study.
Tina Soliman-Hunter does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
