Under climate change, winter will be the best time for bush burn-offs – and that could be bad news for public health


Giovanni Di Virgilio, UNSW; Annette Hirsch, UNSW; Hamish Clarke, University of Wollongong; Jason Evans, UNSW; Jason Sharples, UNSW, and Melissa Hart, UNSW

At the height of last summer’s fires, some commentators claimed “greenies” were preventing hazard reduction burns – also known as prescribed burns – in cooler months. They argued that such burns would have reduced the bushfire intensity.

Fire experts repeatedly dismissed these claims. As then NSW Rural Fire Service Commissioner Shane Fitzsimmons noted in January this year, the number of available days to carry out prescribed burns had reduced because climate change was altering the weather and causing longer fire seasons.




Read more:
How does bushfire smoke affect our health? 6 things you need to know


This public conversation led our research team to ask: if climate change continues at its current rate, how will this change the days suitable for prescribed burning?

Our results, published today, were unexpected. Climate change may actually increase the number of burn days in some places, but the windows of opportunity will shift towards winter months. The bad news is that burning during these months potentially increases the public health impacts of smoke.

A hot debate

Hazard reduction involves removing vegetation that could otherwise fuel a fire, including burning under controlled conditions. But its effectiveness to subdue or prevent fires is often debated in the scientific community.

Commissioner Fitzsimmons weighs in on a national debate about hazard-reduction burns.

Those with experience on fire grounds, including Fitzsimmons, say it’s an important factor in fire management, but “not a pancea”.

Despite the debate, it’s clear hazard reduction burning will continue to be an important part of bushfire risk management in coming decades.




Read more:
The burn legacy: why the science on hazard reduction is contested


Modelling future weather

Before conducting prescribed burns, firefighting agencies consider factors such as vegetation type, proximity to property, desired rate of spread and possible smoke dispersal over populated areas. But we wanted to distil our investigation down to daily weather factors.

We reduced those factors to five key components. These were maximum temperature, relative humidity, wind speed, fuel moisture and the McArthur forest fire danger index (the index used to forecast fire danger in southeast Australia).

We looked at these elements on prescribed burning days between 2004-2015. We then used climate models to simulate how the conditions would change with global warming over southeast Australia, relative to a baseline historical 20-year period for 1990-2009.

To make a valid 20-year comparison, we compared the historical period to a modelled period from 2060-2079, assuming emissions continue to rise at their current pace.

A controlled burn in bushland, with small flames and lots of smoke.
Under global warming, suitable conditions for prescribed burns will be shifted to late winter and early spring in many places.
Shutterstock

Surprisingly, we found, with one regional exception, the number of days suitable for prescribed burning did not change. And in many places, the number increased.

As the fire season lengthened under a warming climate, the number of days suitable for burning just shifted from autumn to winter.

Shifting seasons

Our research indicated that by 2060 there’ll be fewer prescribed burning days during March, April and May. These are the months when most burning happens now.

But there will be significantly more opportunities for burning days from June to October. This is because the conditions that make for a good day for prescribed burning – such as mild and still days – start to shift to winter. Today, weather in these months is unsuitable for conducting burns.

Interestingly, these results aren’t uniform across southeast Australia. For example, much of the Australian east coast and South Australia would see seasonal shifts in burning windows, with around 50% fewer burning days in March to May.

Much of Victoria and in particular the southern regions saw an increase in burning windows during April to May and, in some parts of the state, through September and October as well.

Only the east Queensland coast would see a total reduction in prescribed burn days from April to October.

The smoke trap

This may be good news for firefighters and those agencies who depend on prescribed burning as a key tool in bushfire prevention. But, as so often is the case with climate change, it’s not that simple.

A byproduct of prescribed burning is smoke, and it’s a very significant health issue.

Last year, research showed global warming will strengthen an atmospheric layer that traps pollution close to the land surface, known as the “inversion layer”. This will happen in the years 2060-79, relative to 1990-2009 – especially during winter.




Read more:
The smoke from autumn burn-offs could make coronavirus symptoms worse. It’s not worth the risk


Unfortunately, the conditions that create inversion layers – including cool, still air – correspond with conditions suitable for prescribed burning.

For asthmatics and those sensitive to air pollution, smokier burn days could make winter months more difficult and add further stress to the health system.

It also creates an additional challenge for firefighting agencies, which must already consider whether smoke will linger close to the surface and potentially drift into populated regions during prescribed burns.

This is just one factor our firefighting agencies will need to face in the future as bushfire risk management becomes more complex and challenging under climate change.




Read more:
How does bushfire smoke affect our health? 6 things you need to know


The Conversation


Giovanni Di Virgilio, Research associate, UNSW; Annette Hirsch, Post Doctoral Research Fellow, UNSW; Hamish Clarke, Research Fellow, University of Wollongong; Jason Evans, Professor, UNSW; Jason Sharples, Professor of Bushfire Dynamics, School of Science, UNSW Canberra, UNSW, and Melissa Hart, Graduate Director, ARC Centre of Excellence for Climate Extremes, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

There’s no evidence ‘greenies’ block bushfire hazard reduction but here’s a controlled burn idea worth trying



Locally managed hazard reduction could give communities greater ownership over prevention and leverage local knowledge.
David Bowman, Author provided

Jason Alexandra, RMIT University and David Bowman, University of Tasmania

The current bushfire crisis provides compelling evidence of the dangers posed by extremely dry landscapes and hot, windy conditions.

While there’s no evidence “greenies” precipitated the current crisis by blocking hazard reduction, it is clear that we need to explore new ways to manage fuel loads to reduce the severity of bushfires.

It is worth considering how local, self organised, place-based, community groups could be supported to conduct various types of strategic hazard reduction, including targeted grazing and prescribed or fuel reduction burning.

Using the Landcare model for bushfire hazard reduction

One model we could look to is Landcare, which has enjoyed 30 years of bipartisan support. Funded and supported by governments, local, semi-autonomous, self-directed groups aim to take a sustainable approach to land management through on-ground projects such as habitat restoration and improving biodiversity.

This model could be applied to prescribed or fuel reduction burning, carried out by local “GreenFire” groups. This would involve:

1. Developing and resourcing GreenFire groups.

These would be the equivalent of district Landcare groups, but focused on hazard reduction and fuel management. These groups could be encouraged to learn patch-burning techniques, and other landscape scale management practices, such as creating green firebreaks of non-flammable species.

If well coordinated, these techniques would reduce fire hazards across private and public lands. These groups could be an extension of existing Landcare groups combined with volunteer firefighting services. They would aim to increase capacity for fuel management at the landscape scale and provide opportunities for more people to learn skills and share knowledge, with and from professionals working in government forest and national parks agencies.

These kinds of activities, mostly in the cooler, green seasons would enhance the capacity of communities to prepare for future fires, and increase the capacity of traditional fire fighting to suppress dangerous fires.

2. These groups could work under the mentorship and authorisation of fuel management/reduction officers.

These could be public officers such as district fire officers or senior staff of public land management agencies who have had a long involvement in prescribed burning and fuel management on public lands.

3. In each district, fuel reduction periods could be officially declared.
With this declaration state governments would assume liability for fuel reduction fires, so long as they had the appropriate planning, approvals and resourcing (for example, they were undertaken by trained groups and certified by appropriate officials).

4. Fuel reduction burning should employ Indigenous fire rangers, drawing on Indigenous knowledge and celebrating Indigenous patchwork burning practices.

Involving Indigenous communities in such a program would combine traditional and modern burning practices. Blending cultural and modern burning techniques has proven successful in major savanna burning programs reducing carbon emissions from late season fires in Northern Australia.

Prevention is better than firefighting

Land use planning and management play key roles in shaping exposure to bushfire risks, and are therefore central to disaster mitigation.

Under conditions that favour wildfires, no amount of firefighting effort can protect all lives and property. Victoria’s Black Saturday Royal Commission – a comprehensive inquiry into the fires in which 173 people died, more than 5000 were injured and more than 2,000 houses destroyed – found that under extreme conditions, wildfires overwhelm the capacity of emergency services.

South-eastern Australia has long experience of intense fires, yet our population has spread into the bushlands of coastal hinterlands and urban fringes. This has occurred despite scientists warning for more than 30 years that wildfire risks were intensifying due to climate change.

There are no silver bullet fixes to reduce bushfires hazards. But pragmatic approaches based on extensive research have improved disaster responses, supported calls for stricter planning and building codes and quantified the benefits of strategically reducing fuel loads.

We must try creative new ways to reduce risk

Since the Stretton Royal Commission into the 1939 Black Friday bushfires, more than 16 major inquiries have called for greater use of integrated approaches to land use planning and management to minimise disaster risks.

With climate change increasing bushfire impacts and intensities, we need to build capacity in local communities to manage fire hazard. This requires education, training and adapting policies and landscape management practices to devise plans that suit local conditions.

Countless generations of Indigenous people have effectively managed fire risk through skillful burning. It is time to learn how to burn well and to share the techniques and methods that can enable us live well in our flammable landscape.The Conversation

Jason Alexandra, PhD candidate, RMIT University and David Bowman, Professor of Pyrogeography and Fire Science, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.