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| The negative Southern Annular Mode affecting Australia is set to make conditions difficult for firefighters. (Supplied: Andrew Bedggood) |
"The forests are in a state where even a small ignition source can cause major problems," warned Richard Thornton from the Bushfire and Natural Hazards Cooperative Research Centre.
"And that will only get worse as we move into summer and things dry out even further."
Andrew Watkins from the Bureau of Meteorology says the southern half of Australia has experienced the driest January to August on record.
"When we take into account temperatures as well, which have been highest on record for winter in some of those bushfire areas, we've had high evaporation," he said.
"We have very dry soils and dry fuel as well."
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| There is a trend in southern Australia where the number of dangerous bushfire days are increasing. (Supplied: Bureau of Meteorology) |
Pacific ocean temperatures are not driving Australia's weather right now, with no El Nino or La Nina expected to develop in the coming months.
There is another, less well-known climate driver behind the strong westerly winds fanning the flames.
"We have a period of negative SAM (Southern Annular Mode) affecting us now, as it has on and off for a while," Dr Watkins said.
When the SAM is negative, strong westerly winds like the ones experienced at the weekend reach further north than normal.
What's driving the fire season ahead?
The warm, dry conditions that have led to the early fires are predicted to continue for the rest of the year.
What to do if bushfire threatens  |
| ABC Emergency has sourced advice from official agencies on how to plan for a bushfire, including preparing a survival kit.
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"And likewise with rainfall, there are increased odds of drier than normal conditions for much of eastern Australia right through until January as well."
On top of this, the recent sudden stratospheric warming over Antarctica is predicted to keep SAM negative for the rest of the year, reinforcing the warm, dry conditions in New South Wales and southern Queensland.
Climate change trends
"Climate change is playing its role here, but it's not the cause of these fires," Dr Thornton said.
"We're seeing a degree on average higher temperatures than the long-term average."
Climate change expert Andrew King from Melbourne University agrees.
"It's quite clear that the type of hot weather associated with bushfires is becoming more frequent and more intense and it's also more likely to occur earlier on in the warm season," he said.
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| Darker red and yellow colours show an increase in the length and intensity of the fire weather season since 1978. (Supplied: Bureau of Meteorology) |
"There's not really a very clear trend," Dr King said.
"Overall, we don't really see a clear trend towards more dry conditions or more wet conditions [in southern Queensland].
"We have really highly variable rainfall in eastern Australia, linked with things like El Nino and La Nina, and also individual weather systems."
But he says further south, drought is linked to climate change trends.
The science of bushfires  |
| How does a bushfire begin and spread, and what happens to the environment once it's moved through? |
And when it comes to increased westerly winds like the ones that fanned this week's fires, he said climate science predicts less strong winds.
"The general climate trend is towards more positive SAM conditions, which means that we see those weather systems moving further south away from Australia and associated with that, we wouldn't see the same frequency of westerly winds that we've seen recently in New South Wales and Queensland."
The Bureau of Meteorology's state of the climate report from last year showed the overall fire danger index had increased over the past 40 years over much of southern Australia.
Dr Thornton expects this trend to continue.
"What climate change will do is it will increase the frequency, or the return rate if you like, of really bad fire weather days," he said.
"So the days like where you had Ash Wednesday or black Saturday, the return period for those sorts of days, will come back and will become shorter.
"So we really need to start thinking about how do we prepare properties better for that?
"How do we make sure that communities stay safe?"
Links
- Australian Flammability Monitoring System
- Queensland's bushfire devastation captured in pictures
- The red-hot question after destructive hinterland fire — can rainforests burn?
- Injured koala and her joey Rupert among hundreds of animals rescued from fires
- Murray-Darling Basin in 'most severe' two-to-three year drought conditions in 120 years of records, BOM says
- Rare weather event over Antarctica driving Australia's hot, dry outlook
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