Since Ash Wednesday, organisations such as CSIRO, CFA and others have undertaken a great deal of research to establish why and how houses burn down during bushfires. This research has consistently shown that the vast majority of houses and buildings burn down during a bushfire due to ember attack. How embers can ignite houses ember attack occurs when small burning twigs and leaves, carried ahead of the main fire, land on and around houses before the main fire front arrives. — The CFA’s advice to householders, Living in the Bush.
The crucial point here is that embers, not flame or radiant heat, cause the “vast majority” of houses to burn. In fact, says the CFA, over 90% of houses succumb to delayed, unattended ember attack. Embers are “carried ahead of the main fire”, and houses often burn down hours after the fire front has passed. Therefore if you douse the embers, retreat into the house while the fire front passes, then emerge to put out any incipient fire, you’ll be safe. The CFA’s precise yet contradictory advice is that staying is “a safe option”, giving you “a good chance of survival”, which is not at all the same thing. No-one wants a good chance of survival, they want certain survival.
The CFA fails to distinguish between embers falling in advance of a fire front and an ember blizzard, which occurs when a severe wind-driven wildfire is approaching. Advance embers are low density and usually low speed, falling as gravity transcends windspeed. They can indeed be doused with mop and bucket, as CFA advice states. In a moderate bushfire, it is quite possible that the fire front will “pass” and the house will protect the inhabitants from radiant heat. For intense bushfires, even those well short of a firestorm, this is not wise advice.
Remarkably, the CFA failed to comprehend the primary lesson of the Canberra firestorm of 2003, even though they specifically refer to it in Living in the Bush, “In the Canberra fires of January 2003, wind markedly increased the impact of the bushfire…”
That’s like saying the iceberg markedly decreased the buoyancy of the Titanic.
The fact is that the hopelessly mismanaged Canberra firestorm, which had wandered through the bush for 10 days as an average fire, hit the mature Pinus Radiata plantations on the western edge of the city with storm force, hurling an ember blizzard across a 100 metre bare strip of mown grass and road and into Canberra’s trim suburbs. Four lives and 500 houses were lost. A combination of radiant heat and intense ember attack burned the houses. The fire penetrated hundreds of metres into the suburbs at some points. Pines were culpable, but so were eucalypt forests.
Film of the event leaves no doubt that the fire was unstoppable by the time it reached the wide firebreak of mown grass and road. An ember blizzard in those wind conditions is a horizontal blast of millions of pieces of burning debris. Mops and buckets are as useful as the Titanic’s deckchairs.
What then are we to make of the allegedly copious scientific research which supported the CFA advice? Much of it was based on the Ash Wednesday firestorm in 1983, an event very similar to Black Saturday. The CFA says specifically that the “stay and defend” policy is based on this research. If so, the research is fatally flawed and must in any case be critically reviewed.
My own inspection of the fire ground at Anglesea after Ash Wednesday, supported by photographs and samples, suggested that most houses were ignited by intense radiant heat and/or ember blizzard, not by the delayed effect of advance embers. No doubt the final ember blizzard would have found every bit of combustible fuel in and around each house and in Anglesea there was no shortage of rubbish, stacked firewood or plastic furniture (nothing’s changed). Fibro-cement, for example, disintegrated into tiny fragments as the superheated air pockets inside the sheets expanded. Film of the Marysville fires shows houses burning fiercely, the fire front having just passed.
Not that there is much to choose between an ember blizzard and radiant heat, given that the ember blast hits at essentially the same time as the radiant heat. In a firestorm, the means of ignition is somewhat academic. Given that new fire-rating standards require building materials to withstand a little under 800C, and that most existing houses do not match that, what chance is there of a building surviving in temperatures from 1000 to 2800C, such as experienced in intense bushfires? If the heat doesn’t get you, the ember blizzard will. Wind-driven fire creates a furnace, superheating an already dry target before ember blizzard and maximum heat arrive. Few houses have no fuel around them. Few houses have no chinks in their armour of cladding.
This account is at odds with the following CFA assertion in Living in the Bush: “Research has shown that radiant heat can only ignite timber on a building when a lot of fuel such as forest, overgrown garden or other structures burn quite close to it.”
Once again, ambiguity bedevils this advice. What is “quite close”? 10 metres? 60 metres? The photographs of houses used in these publications by the CFA show vegetation with two or three metres of walls. The forest is perhaps twenty metres away. There’s no doubt that an intense bushfire, let alone a firestorm, can ignite houses quite easily at these distances, either by ember blizzard or radiant heat or both.
The “scientific research”, which appeared in 1991, must therefore be utterly misconceived. Since the CFA based its fatal advice on this research, both the science and the scientists should be examined by the Royal Commission.
Living in the Bush gives very little specific information about fire behaviour. The patronising assumption seems to be that the ordinary citizen is unable to comprehend any abstract concept or technical detail. There is no coherent discussion or warning of the distance flames may reach from the fire front, nor any clear advice on the distance from which radiant heat can ignite buildings or be fatal to humans, nor any discussion of the 1000-2800C degree heat that an intense wildfire can generate.
There is a mention of the difference between a crown fire and a ground fire in Living in the Bush, but no discussion whatever of the significance of crown fires. Large crown fires cannot be fought head-on by firefighters, let alone householders, no matter how “well-prepared”. The speed and intensity of crown fires, which are wind or slope-driven by definition, are such that staying and defending is only feasible in the most advantageous circumstances.
Yet these advantageous circumstances are not discussed by the CFA. The diagram relating to fire speed and slope, shown in isolation as it is, can be no guide to action. Yet without clear technical information, how can householders prepare for wildfire or judge what they should do on the day? Bushfires should be categorised in a hierarchy of intensity, from firestorm to trivial. Advice will vary accordingly.
“Preparation” for Bushfire: CFA Advice
Watching Living in the Bush is a strange, soporific experience. A family sits around a table, making a “fire plan”, checking off points such as mops and leaf litter. The CD, website and current booklet show a few small burns on window and door sills as examples, each with a tiny handful of guilty leaves. The family busily rakes lawns.
After disclaimers about mental and physical fitness, the message is unambiguous: if you are “prepared”, you can safely “stay and defend”.
An ember attack can be dealt with by a wet mop. Since it is radiant heat that kills and embers take hours to burn a house down, you only need to retreat to a quiet dark room inside the house and wait for “10-15 minutes”, which is the time a fire front will take to “pass”. The house is your protection against radiant heat.
Leaving “late” is condemned as far too dangerous. The claim is made that most deaths occur on roads when fleeing fires at the last minute. If you intend to leave, then “leave early”. But “early” is never defined. The reference to “leave before 10am” which has been mentioned since Black Saturday, does not appear in these CFA publications.
On the contrary, the CFA merely states that you should leave “before a fire threatens”. There is no definition of this. If there is smoke nearby, it is probably too late to leave, they say. You may receive no official warning at all, the CFA says, adding that fire trucks probably won’t come to the rescue in any event. Prescient indeed.
Leaving “Late”: the House as Refuge
“Even if the house is unprepared it will protect you from radiant heat as the fire front passes.”
CFA advice on “leaving late” is again wrong and/or ambiguous. It’s a “safer option” to stay in an “unprepared” house than “leave late”, they say. There’s no doubt that leaving by car with a bushfire imminent is very dangerous. Roads may be blocked and cars are flammable. Visibility may be minimal. But it all depends on circumstances. If there’s an exit away from the fire front and the fire hasn’t spotted ahead, driving may be a better bet than staying in the house, especially in a firestorm. Many people, both “prepared” and “unprepared”, died on Black Saturday. Many no doubt died a few metres away from their house, having fled when it became an inferno. The protection a house affords in a firestorm may be mercilessly brief.
The CFA assumption that houses are intrinsically safe in a firestorm, if “prepared” (and even if not, up to a point) is false and dangerous.
Houses should be regarded not as refuges in severe bushfires, but as fuel.
Fire auditing of each property would enable residents to make a more informed decision about staying or leaving if wildfire strikes without warning.
“Preparation” involves removal of fine fuel from around the house.
Misconceptions of the CFA’s Role
“CFA will not always be able to protect each individual property threatened by fire.”
So says Living in the Bush. A profound understatement.
Nowhere does the CFA adequately explain the nature of its firefighting operations. Their task is, first and foremost, to fight the perimeter of fires. It is not “asset protection” as such. That is impossible when severe wildfire threatens many houses. The point is to stop the fire, usually by “containing” it within a defensible perimeter. This perimeter might be a combination of roads, bulldozed firebreaks, back-burned ground, a river or whatever. The worse the fire, the more essential this strategy is. The CFA is not the fire brigade. Sadly, many in the bush don’t realise this. Even fewer in the city.
Further, the CFA no longer permits personnel to fight raging fire fronts. Since 2000, the rule of thumb appears to be to retreat if flame is more than 1.5 metres high. Before 2000, firefighters died taking avoidable risks. That appalling policy of bushfire suppression at any cost, the Gallipoli Syndrome, is thankfully now history. Unfortunately this fact is not well understood by the general public.
The endless crass myth-making we see every summer, fanned by a bushfire-ignorant media, worships CFA volunteers as “heroes” who blithely take horrendous risks to save life and property. The Prime Minister’s hyperbole after Black Saturday is one of the most fatuous expressions of this dangerous nonsense imaginable. In windy, rhetorical tones he lauded the firefighters who stood facing the “gates of hell” with “eyes of steel”. On Black Saturday, they did nothing of the kind.
CFA Advice: What Burns?
Living in the Bush states that flammable plants should not be planted “close” to the house. As usual, the advice is ambiguous. What is “close”?
Critically, all plants are regarded as fuel. This is grossly miseading. Eucalypts and other extremely flammable plants are not specified. Instead we have the following curious injunction:
Avoid plants with the following characteristics … lots of dry, dead debris during the fire season loose flaky bark masses of very fine leaves … a very low moisture content.
This is a coy description of a eucalypt. It omits only the high volatile oil content, a serious omission. Why the bizarre evasiveness? The Tasmanian Fire Service is not so shy, advising that fire resistant plants be used.
Plants with broad fleshy leaves are better than those with fine hard leaves (sclerophyll).
Those with significant amounts of volatile oils, like the eucalypt family which includes eucalypts and tea-trees, should be avoided.
The explanation appears to be ideological: fire resistant trees are almost all “exotics”, and non-native trees and shrubs are officially regarded as “woody weeds”. Consider the following summary of flammability from the Gosford City Council website:
Avoid Plants with high levels of volatile oils in leaves — Eucalypts, Callistemons and Melaleucas burst into flames on heating and increase fire intensity. In eucalypts, the amount of volatile oil in foliage can be over 4%, whereas conifers have up to 2% and Callistemons and Melaleucas up to 1%. Generally the figure is less than 1% for Acacias, Grevilleas and Hakeas. Introduced deciduous and evergreen hardwoods have the lowest amounts with less than 0.1% of volatile oils.
This is commonsense information, yet is absent from CFA advice. It is also absent from other environmental agencies. It is an absence which increases wildfire risk throughout the state. Nativism, expressed as arboreal racism, is at the root of this evasion.
The CFA and related agencies must undergo a complete conceptual, scientific and ideological audit. Their advice to the public has to be drastically altered. It also must be open and sophisticated. Policies such as evacuation and fire bunkers should be revived. Houses should be defined as fuel rather than refuges in severe wildfire. Integrated land management is essential. Many towns are shambolic masses of fuel awaiting ignition. What is the point of defending towns or individual properties if timber plantations are allowed to abut them? What is the point of destroying fire-resistant trees across the state? Why dry out vast areas by “controlled burning” when this won’t impede severe fires, but merely encourage fine fuel growth?
And that’s just for starters …
Frank Campbell is the former Australian editor of international Wildfire magazine. He has made a submission to the Black Saturday Bushfire Royal Commission.