This page lists some useful concepts for thinking about fire, as well as references for further reading.

Fire is ancient

Fire and earth go way, way back. Like, four hundred million years. That’s a cool two million centuries before dinosaurs showed up. Basically, as soon as plants set foot (ahem) on dry land, fire wasn’t far behind.

Why does it matter that fire is ancient?

Many of the plants and animals you see around you today evolved with fire. It’s a part of the evolutionary furniture. It’s also a part of vast, planetary cycles of heat, water and carbon.

Fire is very very very old!
Image credit: David Shooter and Hamish Clarke

References

Fire is global

Although fire can be rare in a given location, nary a day goes by without a fire somewhere on Earth. In fact, there’s so much fire we can see it from space!

Fire can be found in Africa, Europe, Asia, North America, South America and Asia. Antarctica is the only fire-free continent (for now).

Thanks to the miracle of remote sensing, we are starting to get a sense of fire’s fantastically huge footprint on our planet.

Global patterns in fire activity
Image credit: Global patterns in fire activity. From Artés, T., Oom, D., de Rigo, D. et al. A global wildfire dataset for the analysis of fire regimes and fire behaviour. Sci Data 6, 296 (2019). https://doi.org/10.1038/s41597-019-0312-2

References

Fire is local

The key insight of the fire regime concept is that for any flammable landscape, there is a ‘normal’ kind of fire, defined by distinct patterns of fire frequency, fire intensity, fuel type and seasonality.

To some extent, plants and animals are ‘used to’ the local fire regime.

There are many different fire regimes around Australia and indeed all over the world. Much of the action in fire management – as well as land and conservation management – is at the scale of the fire regime.

Fire research including climate risk and climate change impact assessments should take into account the fire regime.

Fire Regime
Image credit: David Shooter and Hamish Clarke

References

  • Gill AM (1975) Fire and the Australian flora: a review. Australian Forestry, 38, 4-25, https://doi.org/10.1080/00049158.1975.10675618
  • Murphy BP, Bradstock RA, Boer MM, Carter J, Cary GJ, Cochrane MA, Fensham RJ, Russell-Smith J, Williamson GJ, Bowman DMJS (2012) Fire regimes of Australia: a pyrogeographic model system. Journal of Biogeography, 40, 1048-1058, https://doi.org/10.1111/jbi.12065
  • Krebs P, Pezzatti GB, Mazzoleni S, Talbot LM, Conedera M (2010) Fire regime: history and definition of a key concept in disturbance ecology. Theory in Biosciences, 129, 53-69, https://doi.org/10.1007/s12064-010-0082-z

Fire has drivers

Although fire is incredibly complex, it is constrained by four dynamic biophysical processes: the accumulation of fuel, or biomass; the drying out of this fuel so it is available to burn; the presence of weather conditions conducive to the spread of fire; and an ignition source to set things off.

Fuel, dryness, weather and ignition can thus be thought of as drivers of fire. Without all four drivers, there won’t be a major landscape fire. They can be thought of as switches of a circuit that all need to be in the ‘on’ position for big fires to occur.

Different fire regimes are characterised by differences in the patterns of these drivers, including which of them is in the ‘on’ position least frequently – and thus potentially most influential in driving overall bushfire risk.

As an example of this concept, consider that in some parts of the country there is plenty of fuel but it doesn’t often dry out enough to make fire likely. In others areas there are frequently hot and dry conditions but the build-up of large, connected areas of fuel is infrequent, preventing large fires.

Tasks for fire managers and researchers include understanding the local pattern of fire drivers and exploring potential climate change effects on each one.

Drivers of Fire
Image credit: David Shooter and Hamish Clarke

References

Fire is risky

One of the reasons we care about fire is because it can cause problems. Risk is one way of thinking about these problems – and things we can do about them.

Risk describes the chance of a threat being realised.

  • It is the product of likelihood and consequence. What is the likelihood of something bad happening, and what is the consequence for some ‘thing’ we care about?
  • The word hazard is sometimes used instead of likelihood, to emphasise the source of risk.
  • For similar reasons, the word impact is sometimes used instead of consequence.
  • Consequence is sometimes broken up into exposure and vulnerability, to emphasise the fact that not all things in the path of a hazard (i.e. exposed to it) are equally vulnerable.

Loss of life is an obvious example of a threat posed by fire. But we can apply the risk concept much more broadly than that, to all kinds of assets – tangible and intangible, human-made and natural, short-term and long-term.

A focus on a very broad range of assets – sometimes referred to as values – subtly shifts the perspective of risk assessments. In the past they tended to focus on which parts of the landscape were more likely to experience fire. Nowadays, they focus on how different things that we care about interact with, respond to and recover from fire.

Tasks for fire managers and researchers include:

  • identifying all the things we care about that are affected by fire
  • understanding the likelihood (and if possible cost) of fire affecting all these things
  • understanding how effective (and cost-effective) (and risky!) our attempts to reduce risk are
Fire simulation
Image Credit: FLARE Wildfire Research. Example of a single bushfire simulation generated by PHOENIX; coloured squares indicate flame height with darker red colours representing higher flame heights and lighter yellows representing lower flame heights.

References

Fire is cultural

Us humans and fire go way back.

Stories around a campfire. Barbecues (did anyone else’s mouth just start watering?). Lighting a candle, rather than cursing the darkness.

Nowadays you won’t get far in understanding fire if you don’t include humans in the equation. We start fires, we put them out, we make laws and institutions, and we study fire.

For tens of thousands of years, diverse and complex cultural fire practices have been a part of Indigenous peoples’ care for Country here in Australia. Fire is part of the history, lore and cultural practices of First Peoples all over the world.

Fire is cultural
Image credit: David Shooter and Hamish Clarke

References

  • Pascoe J et al. (2023) Lighting a pathway: Our obligation to culture and Country. Ecological Management and Restoration, 24(2-3), 153-155, https://doi.org/10.1111/emr.12592
  • Pyne SJ (2020) From Pleistocene to Pyrocene: Fire Replaces Ice. Earth’s Future, 8(11), e2020EF001722, https://doi.org/10.1029/2020EF001722
  • Maclean K., Hankins DL, Christianson AC, Oliveras I, Bilbao BA, Costello O, Langer ER, Robinson CJ (2023) Revitalising Indigenous cultural fire practice: benefits and partnerships.Trends in Ecology and Evolution, 38, 899-902, https://doi.org/10.1016/j.tree.2023.07.001