Australian summers are getting drier and hotter as the Earth’s temperature rises and this is leading to longer and more intense bushfire seasons. On the mainland, we are seeing more frequent fires in the mountains – for instance, in the Mt Hotham area we have seen three serious fires in less than 15 years, which has devastated huge areas of snow gum and alpine ash forests. Snow gum forests are changing under the onslaught of more frequent fire regimes.
In Tasmania, huge fires burnt across Tasmania for months last summer, threatening fire sensitive communities. More than 100,000 hectares were burnt in Victoria. As is becoming increasingly obvious, this is the ‘new normal’. This has implications for landscapes and water supplies, how we manage fires, and how we live in the landscape. This is happening in forests around the world, and people who have traditionally lived in forested areas are having to re-assess how they can do this safely in a time of heightened fire risk.
Recently, ABC Radio Hobart Mornings program asked two experts questions about the challenges of managing the bushfire risk in a changing climate: Will there be more ‘extreme’ and ‘catastrophic’ fire weather days? Are there new approaches to fire management? And how will life change?
The conversation highlighted that the total fire ban days in Tasmania are expected to increase by 75% over next 100 years.
Curious Climate: How the bushfire risk will change as Australian summers get drier and hotter
Total fire ban days set to increase
One audience member asked how the bushfire risk would change over the next 10 to 100 years, and whether there would be more ‘extreme’ and ‘catastrophic’ fire weather days.
Tasmania Fire Service (TFS) director of community safety Sandra White said the TFS worked closely with bodies like the Bureau of Meteorology to project changes.
“It is really likely to change, it is going to increase,” Ms White said.
“The trends show very clearly that those areas in Tasmania that are already some of our highest fire danger areas, it’s going to increase.
“The number of days that are in that very high and above fire danger level will increase.”
Ms White said over the next 100 years it was expected that total fire ban days would increase by 75 per cent.
“It’s real, that’s what’s happening.”
She said higher temperatures, and a decrease in humidity, were drivers behind the risk.
“When you put those things together you start to see a change in the fire danger,” she said.
Plus, there was also the change in annual rainfall patterns.
“The fuels are drying out, so there’s more fuel availability,” she said.
“Regardless of whether there’s a [fire], the actual climatic conditions for that landscape … the modelling is clear they are increasing.”
Lightning, wind-speed forecast difficulties
Professor of pyrogeography at the University of Tasmania David Bowman said at the moment there was only so much that could be projected.
“Climate projections are very good at painting a picture that we’re heating the planet and there’s going to be biological consequences,” he said.
“If you’ve got forests which are being heated and dried you’re going to get events where they’ll burn.”
He said meteorologists could give fire managers very good predictions about the dangers of bushfires within a week.
But he said there were difficulties with predicting fire risk over the next decade or 50 years.
“Could I dial up a computer program and tell you the number of extreme bushfire potential events next summer or in 10 summers’ time? We can’t, we don’t know that,” he said.
“There are lots of reasons we will probably never know that.”
Dr Bowman said landowners should prepare now for the decades ahead in broad terms.
He said in Tasmania two critical ingredients affecting fire were wind speed and lightning.
“They are the big ticket items in terms of a yes or no situation.
“Predicting those oven-dry winds and lightning storms and getting all the combinations lined up is an impossible situation.
“Last summer was not actually as big as people think it was, it could have been many, many times worse had the oven-dry winds from Central Australia come.”
One audience member asked if lightning conductors could be installed throughout the World Heritage Area, particularly in western Tasmania to prevent fires starting from lightning strikes.
One weather event last summer saw 2,000 strikes in a short period of time, and in 2016 there were several big lightning events including one involving 800 individual strikes.
Ms White said lightning conductors would not be practical.
“The practicality of how many lightning rods needed would be an impossible challenge,” she said.
“Which ridges would you pick? Lightning doesn’t just go into the ridges.”
Reimagining fire management
Dr Bowman said the community would need to reimagine fuel management and have to agree to modify the landscape to fight fires with landscape design.
He said “green” firebreaks were being trialled.
“It opens up the understorey in wet forests, mulching basically, to decouple a fire that could develop and get into the crowns,” he said.
“It’s a way of managing fuel using a combination of burning, and machines and design.”
Dr Bowman said communities could rethink firebreaks.
“Fire breaks can be very boring, they’re just bulldozed strips of bare earth,” he said.
“With imagination they can be turned into amenities where they are parks.
“We could start thinning out the bush, modifying the bush and creating … lawns [where marsupials can graze].”
Another idea would be using creek lines as green fire breaks — for example irrigating Hobart’s creeks, lined with less combustible trees, in times of low water.
“Imagine running irrigation lines around creeks and keeping them wet,” he said.
“You could plant or modify existing vegetation.”
Dr Bowman said in other parts of areas Australia fire managers were using blowtorches to get rid of loose bark, a practice called candling.
“It’s an important strategy to reduce spotting,” he said.
Ms White said fire managers were also studying Aboriginal fire-management practices and working with the Indigenous community to learn more.
“We’re looking at how we can reintroduce cultural burning,” she said.
How will life change?
Ms White said planning was already becoming stricter when it came to bushfire-prone areas.
She said there was more advice available on how to construct a home that was more bushfire resistant.
“There are things we do at a long-term scale like how we design and build homes in bushfire-prone areas,” she said.
“We’re certainly seeing changes to house designs, we’re seeing changes in the design of eaves, gutters and the type of glass people use.”
Ms White said there needed to be community acceptance that the climate was changing.
“We’re at the start of something here,” she said.
“We are going have to become a people that get used to living with a really wild climate around us.
“It’s … bounding to extremes like really hot days and really cold events.”
She said it wasn’t just warmer days but rain as well.
“It won’t come in nice steady patterns, but it will come in intense events, so an increase in flooding.”
Dr Bowman said the changing climate also brought opportunities.
“This is a really exciting moment to be engaging with the environment,” he said.
“It’s our test for how we are going to adapt.
“The forces we are dealing with are very big.”
Curious Climate Tasmania is a public-powered science project bridging the gap between experts and audiences with credible, relevant information about climate change. The project is a collaboration between ABC Hobart, UTAS Centre for Marine Socioecology, the Institute for Marine and Antarctic Studies (IMAS), the Tasmanian Institute of Agriculture (TIA), and the CSIRO.