Bushfires

Two myths about climate change and bushfire management are often repeated in the media:

1. Because of global warming, Australia will be increasingly subject to uncontrollable holocaust-like “megafires”; and

2. Fuel reduction by prescribed burning must cease because it releases carbon dioxide into the atmosphere, thus exacerbating global warming and the occurrence of megafires.

Both statements are incorrect. However they represent the sort of plausible-sounding assertions which, if repeated often enough, can take on a life of their own and lead eventually to damaging policy change.

I’m paraphrasing from an important new report entitled ‘Bushfires, Prescribed Burning and Global Warming’ by Roger Underwood, Chairman of the Bushfire Front, David Packham, Senior Research Fellow at the School of Geography and Environmental Science, Monash University, and Phil Cheney, Honorary Research Fellow, CSIRO, Canberra.

The authors consider in detail at the carbon balance in relation to fire in the three most typical Australian ecosystems: tropical grasslands, tropical/subtropical savannahs and tall forests and conclude:

1. Although the situation is almost carbon-neutral, all fires in tropical grasslands actually sequester some carbon in the form of “black carbon” which is incorporated into the soil;

2. Over time, the carbon balance of fires in tropical and subtropical savannahs is also just about neutral. In some years more CO2 is emitted to the atmosphere from fires than is absorbed by post-fire regrowth, while in other years more carbon is taken up by regrowth than is lost to the atmosphere from fire (including prescribed burning and wildfires).

The management approach that will optimise storage of carbon in Australian savannahs is one of low-intensity, early dry-season burning under mild weather conditions. This protects the overstorey trees and woody shrubs which are consumed by hot late-season fires.

3. Tall forests store carbon in tree trunks, bark, branches and roots, in woody shrubs and mid-storey vegetation and in the litter and accumulated organic debris on the ground. Eventually all old trees begin to decay from within, and in the absence of fire, the accumulated litter on the forest floor begins to rot away. At this point, the rate of release of carbon through decay exceeds the rate of storage of carbon by new growth. Thus Australia’s “old growth” eucalypt forests eventually stop being a carbon sink and become a source of CO2.

Fuel reduction by prescribed burning employs low-intensity fires lit under mild weather conditions at a time when there is still some moisture in the fuel. This ensures that the flames are generally less than a metre high and the fire is confined to the surface layer of fine fuel and the green material in the low shrubs. A properly managed prescribed fire will be conducted at a time when organic matter (including charcoal) in the soil will not burn. The ideal prescribed burn consumes only the surface fuels, leaving behind a layer of ash protecting the soil and the heavy logs.

The amount of CO2 released by a low-intensity fire is small and the store of carbon on the forest floor is rapidly replaced as the fine fuels re-accumulate and the low shrubs regrow. By comparison, a hot summer bushfire burning under drought conditions will consume all of the surface fuels, including large logs and organic matter in the soil which may have accumulated carbon for thousands of years. An intense summer bushfire will even consume the canopies of the tallest trees. The amount of CO2 produced by a fire is directly proportional to the total amount of fuel consumed in the fire. Thus a hot summer bushfire [in Australia’s tall forests] will release massive amounts of carbon.

The authors conclude that from the point of view of carbon storage in grasslands, savannahs and tall forests, the best management approach is one in which large high-intensity wildfires are minimised by periodic prescribed burns carried out under mild weather conditions.

The authors also examine the alarmist concept that “global warming will lead to unstoppable megafires”. They observe that if the current climate change models are correct, there will only be an increase in average annual temperatures of between 2 and 4 degrees over the next 100 years. The effect of this on bushfire behaviour, by itself, will be trivial. Fire intensity is far more significantly affected by fuel quantity, fuel dryness and wind strength, than it is by temperature.

Some climate change computer models also suggest a significant reduction in rainfall, leading to increased fuel drying and increased fuel availability at lower temperatures. This is the same effect as that of drought, a phenomenon which is common in Australia. Drought does result in more intense fires…..but only if nothing is done to reduce fuels before the fire occurs.

The factor which “doomsday” commentators ignore is the opportunity for land managers to get in first, and reduce fuels before a potential megafire starts. In other words, the potential megafire can be forestalled, simply by the adoption of a program of fuel reduction prescribed burning under mild weather conditions.

Finally, the authors advocate that the Precautionary Principle must apply: this means playing safe while the research is being done. The safe approach is not to ban prescribed burning because of an unsupported assertion that it may increase atmospheric CO2 levels, but to promote prescribed burning because it reduces the size and intensity of wildfires.

Bush fires are threatening suburbs in Southern California. …several homes in Los Angeles and Ventura counties were evacuated. Seven-hundred fire-fighters battled the blazes, the largest covered 2,800 hectares. The fires were whipped by high winds of up to 70 km/h. Some homes were destroyed and flames and smoke were visible for several kilometres.

Read more here: http://www.cbc.ca/world/story/2005/09/29/california_fires20050929.html

And that article is a couple of years old. Yesterday CBC was reporting:

Firefighters in Southern California are battling more than a dozen wildfires that have destroyed 16,000 hectares of land and forced the evacuation of more than 250,000 people from their homes in the area. …Arnold Schwarzenegger, who declared a state of emergency late Sunday in seven counties where fires have killed one person and injured dozens, said Monday that “it’s a tragic time for California.”

Read more here: http://www.cbc.ca/world/story/2007/10/22/fire-california.html

Reports in the media and from fire management colleagues indicate that the recent horrific bushfires in Greece have parallels in Australia and were predictable.

It is estimated that nearly 70 lives have been lost and close to 200,000 hectares of agricultural land, national parks and mountain forests have been incinerated. The loss of olive groves is economically disastrous. Similarly the mountain forests are mostly coniferous, and unlike eucalypt forests, are destroyed by high intensity fire. Serious soil erosion and flooding can be expected in the coming winters.

Like southern Australia, Greece has a Mediterranean climate with cool, rainy winters and hot dry summers – ideal conditions for bushfires. Traditionally, however, it has not had disastrous all-consuming wildfires even in previous periods of below average rainfall. What is going on? It appears that the answer lies not in “global warming” as the usual people are inevitably saying, but in land use changes, mismanagement and inappropriate policy. Three things stand out:

1. Loss of land to traditional rural people. Over the last 20 years of so there has been a splurge of buying-up of small rural properties by wealthy people from European countries. A luxury holiday villa is built, and the new owners retire there, or pop in now and again to enjoy the warmth and beauty of the Greek mountains. However, just as when wealthy people from Perth buy their little vineyard in the karri forest, or move to a property on the edge of the bush in the hills, the first thing they do is try to change traditional land use practices, especially burning, and to introduce a “new environmental awareness”.

Mild burning in spring and autumn has been a practice of villagers and small land owners for centuries in Greece for all the usual reasons – including producing fresh grass for grazing, keeping the woods healthy and maintaining a low fire hazard. Increasingly burning has declined as the former land owners move to larger towns, and the new owners fail to do the job.

2. Transfer of bushfire responsibilities from land managers to emergency services. A few years ago the Greek government decided to take fire management responsibilities away from their Forestry Service and give them to the fire brigades. Almost immediately, routine burning programs in forest areas ceased. The bushfire service was confident it could tackle any fire, but this view was based on their experience with fires which occurred in forests which had been prescribed burnt for generations.

Once burning stopped, fuels began to accumulate, and when this fuel became dry in the current drought period, the resulting fires were unstoppable. As is so often the case world-wide, fire services tend to have a “suppression mentality” and do not sufficiently involve themselves in the essential work of bushfire preparedness and damage mitigation. Greek foresters could see it all coming, but did not have the political support to get anyone to face up to the coming crisis.

3. Reliance on technology. Greek authorities have been seduced into investing huge sums of money into aerial fire fighting technology. This was sold to them as the answer to the maiden’s prayer. At the same time, traditional ground-based systems, including access for fire fighters and old-fashioned pre-suppression work, were allowed to run down. The result: when there were many simultaneous fires, the new system was simply overwhelmed. There were not enough water bombers to tackle a large number of small fires, and then when the small fires rapidly became large and intense, the water bombers were ineffective.

Australian bushfire specialists listen to all this with a rueful expression on their faces, or roll their eyes with despair.

Analysis of the massive bushfires in Victoria, ACT and NSW in recent years indicate exactly the same patterns have emerged in Australia, with almost exactly the same result.

We have been lucky that only a small number of lives have been lost. But this may not be the case in the next bad fire season. If Australian governments continue to go down the line of replacing land managers with emergency services, investing in massive aerial technology instead of permanent staff and preparedness programs on the ground, and allowing bushfire policies to be dictated by people from the inner suburbs of the big cities who have no practical experience, the bushfire situation will only get worse here, as it has in Greece.

Roger Underwood is a former General Manager of CALM in Western Australia, a regional and district manager, a research manager and bushfire specialist. Roger currently directs a consultancy practice with a focus on bushfire management. He lives in Perth, Western Australia.