'Unprecedented dryness' points to busy fire season in Australia's east
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'Unprecedented dryness' points to busy fire season in Australia's east

Record heat and well below average rainfall has primed forested areas of eastern Australia for an early and busier than usual bushfire season, according to fire authorities and researchers.

The Southern Australia Seasonal Bushfire Outlook report, released on Thursday, is aimed at helping agencies to prepare resources for the coming fire season - and this year looks like being an active one.

"The combination of warming and drying has led to extensive and historically unprecedented landscape dryness across much of southern Australia," the report said.

Year-to-date maximum temperatures across Australia are running at a record rate - 1.36 degrees above the 1961-90 average - exacerbating the impact of well-below average rainfall by increasing evaporation.

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NSW, all of which has been declared to be in drought, posted its driest January-July period since 1965 and August registered rainfall totals 57 per cent below average for the month, the Bureau of Meteorology said.

"With the short- to medium-range climate outlooks favouring warmer and drier than average conditions across much of the state, there is significant concern for the potential of an above-normal fire season in forested areas on and east of the Divide," the report said.

A helicopter water bombs a bushfire threatening homes in Sydney's south-west in April 2018.

A helicopter water bombs a bushfire threatening homes in Sydney's south-west in April 2018.Credit:AAP

The threat in forested regions extends northwards into south-eastern Queensland but also southwards into Victoria's Gippsland.

The outlook noted that much of East Gippsland had experienced two consecutive years of record low rainfall during autumn and winter, typically among the wettest times of the year.

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"As a result, forests are significantly more flammable than normal, due to an increase in dead material in the near surface and elevated fuels," the reported said.

Pockets of south-western WA also face above-average risk of an active fire season despite good winter rainfall. Persistent deep root zone soil moisture deficits along the Darling Range, south west corner, South Coast, Mallee and Esperance Plains have resulted in the forest and shrubland vegetation in these areas subjected to additional water stress, the report said.

Officially under way

The report, released at the annual bushfire conference held this year in Perth by the Bushfire & Natural Hazards Cooperative Research Centre, noted how the fire season had already got under way with large blazes in several states.

All coastal local government areas of NSW had already begun their official fire season by September 1, with many of them bringing it forward by at least a month. The ACT, too, started its official fire season a month early at the start of September.

Ominous signs for a busy fire season in forested areas of eastern Australia this summer - if not before.

Ominous signs for a busy fire season in forested areas of eastern Australia this summer - if not before.Credit:Nick Moir

"Large fires requiring regional-level bushfire suppression operations can be expected [in the ACT]," the report said.

While the expanding drought has elevated the chances of significant fire activity in wooded regions of eastern Australia, the lack of rain has reduced the threat from grass fires in inland areas because of the lack of moisture in grasslands.

The report noted that the outlook for spring - including the possibility of an El Nino event forming by the season's end - contributed to predictions for a busier-than-normal fire season.

Almost all the country can expect above-average daytime temperatures in spring, while the odds also favour below-average rains in southern Australia, especially western Victoria.

Climate change's signal

Aside from the near-term conditions, however, the report also highlighted the background effect climate change is having on raising the bushfire threats.

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Southern Australia, for instance, had experience above-average temperatures for 22 consecutive years, while cool-season rainfall had shifted to lower totals since the 1970s for south-west WA and the mid-1990s for south-eastern Australia.

"Fire season severity is increasing across southern Australia as measured by annual indices of the Forest Fire Danger Index," it said, with the biggest increases coming in inland eastern Australia and coastal
Western Australia.

"For example, the Victorian annual Forest Fire Danger Index has increased by about 50 per cent since
1950, with particularly high values during the severe fire seasons of 2002/03, 2006/07, 2008/09 and 2015/16," it said.

Peter Hannam is Environment Editor at The Sydney Morning Herald. He covers broad environmental issues ranging from climate change to renewable energy for Fairfax Media.