So what’s a catastrophic fire warning anyway?

If you are aware of news from Australia then you may be aware that tomorrow (Tuesday 12 November) has been given a fire danger rating of “Catastrophic” for Sydney and surrounding regions. Large parts of northern New South Wales are already suffering dangerous bush fires with several fatalities. Weather conditions in the Sydney area are set to be dry, hot and windy tomorrow and with fire services already stretched, people are worried*.

You can read about the fire danger ratings here but I thought I’d write about them as well because they are interesting solution to a problem.

Let’s deal with what they are not. A “catastrophic” level is NOT a prediction. Tomorrow nothing additional could occur. Indeed, days with the “extreme” level (the next level down and until recently the highest level) are not uncommon in many parts of Australia. They can pass without incident.

The warning level is not wholly unrelated to the chance of a fire but there purpose is not to predict a catastrophic fire but to evaluate conditions. In this case numerous factors are coming together over different timescales.

  • It’s November and naturally it is getting warmer just because of the seasons.
  • Less naturally there is an extreme drought in the region. Rainfall has been low which means surrounding bushland is very dry.
  • As well as it being naturally warmer, global warming is playing it’s part and making Australia just that bit warmer on average (and probably implicated in the drought).
  • This week specifically is set to be hot and dry.
  • Tomorrow, is going to be windy.

So there is a combination of lots of fuel, low humidity and a hot dry wind. None of those mean a fire will start but if one does it will be perfect conditions for the fire to spread and to spread quickly and burn fiercely.

The current government is not happy if you mention climate change though: People in country areas who are suffering the biggest burden of both drought and the fires so far are pointing out that, no, really climate change is part of the problem.

Sydney itself is surrounded by undeveloped bushland. The terrain in places like the Blue Mountains** is heavily forested canyons and rocky ridges. Many Australian trees are adapted to bush fires and give off volatile oils, which is nice I guess if you like trees that plot to burst into flames.

Now while Sydney is not about to be consumed by a massive firestorm (I hope) that doesn’t mean ‘catastrophic’ is alarmism. They key issue is that fire can travel quickly and hence if people are going to evacuate the safest time to do so is before there are any fires near by. Which is a dilemma, leave early and you may feel silly. Leave late and you may die horribly in your car. When a fire is close, staying put in a house is a safer choice but even modern Australian homes aren’t built to survive catastrophic conditions.

*[I’m not worried but only because I live in a fantasy world of self delusion.]

**[Not mountains and not blue]

11 thoughts on “So what’s a catastrophic fire warning anyway?

  1. Northern California person here, still breathing smoke from fires to the north of me, and appalled to be watching as your fire season kicks off now too.
    I don’t do prayers so much, but my thoughts are with you.
    (And with my kid too, though ACT doesn’t seem to be actively burning at the moment.

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  2. I’ve noted before that there is a reason that fire crews were one of the earlier things to be formally organized as governments formed. That’s because an out of control fire is everybody’s problem, and if you think it isn’t now, it will be soon enough.

    (I remember watching firefighting airplanes load up with water by doing low scoops over Christina Lake in British Columbia. This included the year the Worldcon was in Spokane and had to deal with smoke. Firefighting involves very active cross-border collaboration around there for the same reasons.)

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  3. Crossing my fingers for you guys tomorrow. I was living in Canberra in 2003 and, yeah, it was not fun…


  4. I may have picked the wrong month to move to Sydney. (Originally from New Zealand, more recently Germany. Then I had the opportunity to move back to this corner of the world…)

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