Fuel Loads Not Climate Change Are Making Bushfires More Severe

Fuel Loads Not Climate Change Are Making Bushfires More Severe

by David Evans

11 November 2019


People have been burning off to keep fuel loads low in Australia for thousands of years. From very long experience, we know that you have to burn off the undergrowth every ten years, and preferably every six. If you don’t, the inevitable fire is too destructive and too intense — a danger to life and property.

How do you start a fire in a fireplace? You stack up dry kindling around the logs and branches. The forests typical of most of Australia are like a fireplace. Building your house in among the trees is lovely, but building in a fireplace might get you killed.

Current fuel loads are now typically 30 tonnes per hectare in the forests of southeast Australia, compared to maybe 8 tonnes per hectare in the recent and ancient pasts. So fires burn hotter and longer.

The fuel load figures are hard to obtain, which is scandalous considering their central importance. There is also confusion over whether to include all material dropped by the trees, or just the material less than 6mm thick — it is mainly the finer material that contributes to the flame front.

Yes, the Australian Government does know roughly how much mulch and debris there is on the forest floor at any point in Australia. They estimate it for Australia’s carbon account, for the ongoing Kyoto Protocol. I know, because I built the system for the Australian Greenhouse Office (search on “FullCAM”). The Dept of Environment can estimate the mass of the trees, debris, and mulch on each 25 meter by 25 meter plot anywhere in Australia, using satellite data, plant data, weather and soil data, etc. Good enough for international accounting and estimating carbon emissions from the biosphere, it might be helpful in indicating where burn offs are needed most.

The old advice to either fight or flee when a bushfire approached, and to defend property, only made sense when fuel loads were light. The fire wasn’t too hot, it was over in a few minutes, and we could survive. With the high fuel loads of today, fighting the fire is often too dangerous.

Eucalypts love fire, because it gives them an advantage over competing tree species. Eucalypts regenerate very quickly after a fire, much faster than other trees, so periodic fires ensure the dominance of eucalypts in the forest. Eucalypts have evolved to encourage fires, dropping copious amounts of easily flammable litter. Stringy bark trees are the worst, dangling flammable strings of bark that catch alight and detach from the tree to spread the fire a kilometer or two downwind.

Bill Gammage wrote an excellent book, The Biggest Estate on Earth: How Aborigines made Australia, which was awarded the Prime Minister’s Prize for Australian History and the Victorian Premier’s Literary Award in 2012. The first Europeans in Australia noted over and over that Australia looked like a country estate in England, like a park with open woodlands, extensive grassy patches, and abundant wildlife. Where Europeans prevented aborigines from tending their land it became overgrown, and the inevitable fires became dangerous and uncontrollable.

Particularly memorable is the account of driving a horse and carriage from Hobart to Launceston in the early 1800s, before there were any roads, simply by driving along the grassy park underneath the tree canopies. Try doing that today through any bush in southern Australia.

The Blame is Obvious

Who changed the policies of millennia, and “forgot” to burn off?

When whites came to Australia they didn’t understand at first how to manage the forests. Where they displaced the aboriginals, the wild fires started soon after. But they eventually learned.

What about the modern era of mega fires? Who caused that?

Here is the burn-off and wild fire data for Western Australia:

A big lesson was learned in 1960 after some mega fires, and a regime of burn offs was instituted. Problem solved.

But then from the 1960s onward policy was increasingly influenced by people with romantic but unrealistic notions — the Greens. Their fantasy is that natural is best. They childishly figured that leaving forests alone and not burning or thinning was the most moral policy. It made them feel best.

Dangerous, foolish greens. The graph tells the story. Burn offs declined, fuel loads built up, then the fires started again in earnest.

To solve the problem, change the policies. And to do that, we probably need to replace our current incompetent ruling class.  Incompetent? Well what would you call letting “unprecedented” huge blazes spring up, then blaming it on climate change? Fools or liars, take your pick.

Climate Change?

If there was any specific evidence that linked climate change to bushfires or extreme weather events, we know the usual suspects would be trumpeting it loudly. That they don’t, speaks volumes.

There was a fifteen year hiatus in the rise of average global air temperatures, from 1998 to 2013. Basically the world didn’t warm for a decade and a half. Yet the bushfire situation steadily worsened in Australia in those fifteen years. Hmmm.

A search through old Australian newspapers on Trove reveals that there have been fire seasons this bad before, and/or that started earlier. Hardly hidden information, but not presented to you by the nightly “news.”

The bibles of mainstream climate change are the Assessment Reports issued by the Intergovernmental Panel on Climate Change (IPCC) every five to nine years. The latest was issued in September 2013. Significantly, it backs away from the link between climate change and specific extreme weather events.

The IPCC says that connections of warming to extreme weather have not been found. “There is medium evidence and high agreement that long-term trends in normalized losses [that is, adjusted for exposure and wealth of the increasing populations] have not been attributed to natural or anthropogenic climate change.” The IPCC claim only to have “low confidence” in their ability to project “changes in frequency and duration of megadroughts.”

The official report does say that “drought, coupled with extreme heat and low humidity, can increase the risk of wildfire” Droughts come along pretty often in southeast Australia.

They also say “there is evidence that future climate change could lead to increases in the occurrence of wildfires because of changes in fuel availability, readiness of the fuel to burn and ignition sources.” Carbon dioxide is a potent plant fertilizer. According to NASA satellites there is more living plant matter today, with a 6% increase in the twenty years to 2000. So there is more to burn.

Logic might help. Global warming has increased temperatures by less than one degree since 1900. Temperatures increase as you go north in Australia. So, the global warming since 1900 is like adopting the climate of a place a few hundred kilometers further north. So, if it was climate change causing the changes to fires, you’d expect a given region to adopt the fire profile of what was a few hundred kilometers further north, a century ago. Obviously the current situation is nothing like that. The fire situation near Sydney today is nothing like Newcastle or Port Macquarie in 1900.

The same logic applies to the reef. If warming is so deadly to coral, how does coral further north survive? Furthermore, the reef is hundreds of thousands of years old, yet during the last ice age, which ended ten thousand years ago, the sea was a hundred meters lower and the reef was hundreds of kilometers to the east of where it is now. How did the reef march so far?

Both questions are answered by the fact that the reef is a population of organisms with a range of tolerances and temperatures at which they thrive. When conditions change, different individuals take over or die. When an El Nino event warms the Pacific and sends drought to eastern Australia, which happens every five years or so, the water temperatures along the reef rise a degree or so. Some corals die, but others do better. And when the El Nino recedes, the situation is reversed. This does not mean we have to let international committees dictate our energy use and lifestyles, as some would have it.