The fire season in parts of eastern Australia has lengthened by almost four months since the 1950s, with climate change a prominent driver in the trend, the Bureau of Meteorology says.
Karl Braganza, head of the bureau's climate monitoring, told the first day of public hearings for the Royal Commission into National Natural Disaster Arrangements on Monday that the South Coast of NSW and eastern Victoria now see fire weather arriving three months earlier, occurring towards the end of winter rather than the end of spring.
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| Firefighters overwhelmed by flames at bushfire in Orangeville in NSW in early December. Credit: Nick Moir> |
At the end of the season, both areas were also reporting fire conditions - when the main index tracking risks tops 25 - extending about 21-30 days further into autumn, Dr Braganza said.
The longer season had implications for agencies trying to combat bushfires, with overlapping conditions stretching resources at home and abroad with similar climate trends appearing in other nations.
The royal commission is one of several inquiries under way, including the NSW government inquiry. Both are keen to wrap up before the new fire season begins, with the NSW report due by the end of July and the federal royal commission reporting a month later.
Dr Braganza's evidence emphasised how the background warming climate was "loading the dice" by exacerbating Australia's natural variability. For instance, the number of days of extreme heat with daily mean temperatures in the top 1 per cent had soared.
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| The trend for the South Coast of NSW in particular is for an earlier start to the bushfire season, as measured by the first day when the fire index tops 25. Credit: Bureau of Meteorology LARGE IMAGE |
While the past season's bushfires had been set up by conditions in the Indian Ocean and the Southern Ocean that favoured drier-than-average conditions, the longer-term warming trend and the drying out of southern Australia during the cooler April-October period also played a role, Dr Braganza said.
The first two decades of this century stand out as warmer than any previous period, increasing the odds of extreme weather, including more severe bushfires.
"Really since the Canberra 2003 fires every jurisdiction in Australia has seen this," Dr Braganza said. "[We] have seen some really significant fire events that have challenged what we do to respond to them, and have really challenged what we thought fire weather looked like preceding this period."
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| Days of 'heat spikes' across Australia have been increasing as the climate warms both here and globally, the bureau says. Credit: Bureau of Meteorology LARGE IMAGE |
For instance, much of Australia could endure extended periods above 48 degrees if conditions during the 2009 Black Saturday run-up were repeated and the expected climate warming added in, bureau modelling showed.
While the past summer was bad, conditions could have been worse, Dr Braganza said.
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| Extreme heat in the future. Credit: Bureau of Meteorology LARGE IMAGE |
The neutral conditions in the Pacific also moderated the possible extremes had there been an El Nino event, which often accompanies the type of conditions observed in the Indian and Southern oceans, Dr Braganza said.
He added this year was expected to get a lot more rainfall than in 2018 and 2019, which could lessen the severity for the upcoming bushfire season.
"At this point what we would be saying is your chances of getting the sort of season that you saw in 2018, 2019 and 2019-2020 are reduced," he said.
The royal commission will also address the wider issues of co-ordination, preparedness, responses, and recovery, natural disasters, as well as improving resilience and adapting to changing climatic conditions.
Senior Principal Research Scientist at CSIRO Helen Cleugh said, as the climate warmed, droughts and fire seasons were expected to worsen, while sea levels were expected to rise.
"For the next few decades, the rates of sea-level rise, both globally and here in Australia are partially locked in by our past emissions but, as we look further into the later century and to centuries beyond that, beyond 2100, those sea levels projections critically depend on the greenhouse gas emissions from now onwards," Dr Cleugh said.
The commission also heard from risk assessment experts on Monday afternoon. Sharanjit Paddam from the Actuaries Institute of Australia said it would be wrong to assess the impact of bushfires solely by looking at property losses from the so-called Black Summer, which destroyed around 3000 houses.
“The hail storms that hit Canberra a few months ago [on January 20], in 15 minutes those hail storms damaged a whole suburb, they were hitting things in the middle of a city … and if we were to do it per-second of natural disaster, that would be far more than six months of bushfires,” Mr Paddam said.
“People's lives, even if they're insured to the full extent of the damage, are very adversely affected by these natural disasters.”
Dr Ryan Crompton of Risk Frontiers said bushfires ranked fourth in terms of fatalities caused by natural disasters, accounting for 10 per cent of deaths between 1900 and 2015.
Extreme heat caused 4555 fatalities, or 46 per cent, and bushfires had caused 974, or one-tenth. Floods have accounted for 19 per cent of deaths and cyclones 12 per cent.
Risk Frontiers' figures include Victoria’s Black Saturday bushfires in 2009, which killed 173. It does not include last summer, when 33 people perished in the fire season.
The federal inquiry attracted almost 1700 submissions from individuals, companies and government bodies, about 100 more than its NSW counterpart. As of May 22, the commission has received more than 16,000 documents on discovery, totalling about 200,000 pages.
Six witnesses are expected to appear on Tuesday, including Mallacoota residents, the Red Cross and Australian Financial Complaints Authority.
Links
- 'Incredibly blessed': Royal commission to eye fire success and failure
- 'Unbelievable what's happening': Fire inquiry reviews 1000 submissions
- Bushfire royal commission: 'Black Summer' played out exactly as scientists predicted it would
- Bureau of Meteorology predicted the devastating "Black Summer" weather
- Ex-ESA Chief wants Bushfire Royal Commission to address climate change
- Australia's 'Black Summer' bushfires 'not a one-off event', royal commission hears
- Royal commission into bushfire crisis begins hearings with focus on impact of climate change
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