Living with megafires - Ramboll Group

Clinton Rakich

January 11, 2024

bush fire uncontrolled , climate change, environmental pollution, dense flames and smoke

Naturally occurring wildfires are an evolutionary force that has shaped ecosystems across the planet for millions of years. The human mastery of fire in the landscape contributed significantly to our success as a species. However, with wildfire frequency and intensity on the rise, we need to reflect on our relationship with fire.

As it is summertime in the southern hemisphere, forest fires are on the minds of many Australians. Can you tell us about the concerns on the ground?

Clinton Rakich: Australia’s Black Summer of 2019 is still very much in our thoughts. The scale was truly unfathomable, with 24 million hectares scorched, 830 million tonnes of CO2 released, and potentially over a billion animals lost, driving many threatened species closer to extinction.

In Australia, like many other countries all over the world, we’re experiencing higher temperatures and altered rainfall regimes in recent years. Think of it this way; a warmer atmosphere is a thirstier one, which pulls moisture from the biosphere by desiccating vegetation and soils, and this creates the ideal conditions for the rapid spread of wildfires. Fire weather is now so severe that fire behaviour has been reported as showing no variation between day and night. These fires are also now often so vast and intense that they generate their own weather systems, pyrocumulonimbus, otherwise known as fire storms. Some of these are large enough to generate lightning and strong winds which can in turn ignite and propagate more fires across the landscape. Wildfires are not just becoming commonplace in Australia, but also in many other regions of the world such as, Europe, Canada, and the United States. The most alarming region to experience wildfires is the Arctic, which is warming fastest and holds vast carbon stores in both vegetation, peat, and permafrost. In the summer of 2022 alone, more than 12,000 square kilometres across Alaska were destroyed by wildfires—that’s roughly triple the annual average.

We’re now gripped by the new global phenomenon of megafires – that’s the term used to describe wildfires which are extreme in size, behaviour, and impacts. The most obvious driving factor is climate change.

Clinton Rakich,

Sustainability Lead, Ramboll Australia.

What apart from climate change is driving the onset of megafires?

An obvious one is the encroachment of our agricultural areas and growing city populations on nature. As the rural and urban fringe pushes into remnant vegetation, the risk of fire increases. Other sources of increased fire frequency and intensity, especially in the tropics, are deforestation and the clearing of land for agriculture. In some places, such as Indonesia, wetlands containing vast carbon stores of peat have been drained and then exposed to fire during droughts, resulting in immense carbon emissions and toxic air pollution.

As we try to restore, repair and regenerate nature in line with the ambitions of the Global Biodiversity Framework, we’re faced with the daunting prospect of amplifying wildfire threats across many parts of the world.

Is there a risk of restoration efforts being obliterated by a second fire event?

As fire frequency increases, there will be larger burnt zones for which there have not been sufficient recovery time since the last disturbance. Frequent intense fires can limit forest regeneration, deplete soil seed banks, open the canopy, and expose the near surface vegetation to the desiccating impacts of solar radiation, and higher wind speeds and temperatures. Together, these factors increase the fire risk and raise the risk of fire frequency increasing beyond the rate of regeneration of the canopy of forests, woodlands, and shrublands.

Our increased use of fire to manage the environment has often resulted in a greater abundance of more flammable and fire tolerant plant species.

This results in fire prone landscapes becoming increasingly flammable, and also assists the spread of easily ignited grasses and annual herbaceous weeds which can colonise and outcompete native flora in disturbed landscapes.

In Western Australia, prescribed burning is taking place almost at military scale, where incendiary devices are dropped from planes, burning a target of 200,000 hectares per year, with little regard to the complex lifecycles of the wildlife and plants in this region of high endemic biodiversity. There is also little regard for the vast carbon emissions from fire events and the compounding impacts of a rapidly drying climate and frequent burning regimes. Recent data from Curtin University shows that frequent fires, whether through prescribed burns or uncontrolled wildfire, change the forest structure, making it more flammable and enabling the fire to move faster. It potentially shortens the time during which people can evacuate safely, so it ends up increasing the risk of the hazard we’re trying to prevent.

In contrast, old growth, undisturbed forests dominated by more widely spaced mature trees, and thinner understorey have been found to be three times less flammable in comparison to those which have been impacted by prescribed burns.

This latest scientific evidence runs counter to the current landscape scale prescribed burning practices used to supposedly reduce fire risk to communities. There is also increasing awareness of the negative impacts of prescribed burning at landscape scales on air quality, human health, biodiversity, and ecosystem services.

How can we manage land and biodiversity assets in fire prone regions?

Managers of biodiversity assets will require new techniques to ensure their biodiversity and carbon sequestration projects will be resilient to fire and recover from impacts across the required 30-year monitoring period. Strategic interventions are required to break the occurrence of frequent wildfires that’s creating a less biodiverse, more flammable, and increasingly fire-prone landscape.

We need to change the way we approach fire resilience, protect our natural carbon stores and help our ecosystems recover and fully regenerate after an event.

We need to understand that it’s not about dealing with one hazard in isolation at any one time – a specific flood, drought, fire. It's about biosphere management, and we're part of the biosphere, so a more holistic overview is needed.

We could look to the methods used by Australia’s First Nations people. They practice precise and strategic low intensity fires that slowly move across the base of the forest floor, burning the leaf litter and safely reducing the fuel loads in defined buffers around important sites of cultural and ecological importance. They work with nature and ensure the conditions allow for fires which are as smoky and light as possible, as the smoke warns the insects and animals and gives them time to escape, often into the forest canopy. When the fire passes, the insects and animals return and replenish the forest. The First Nations people concentrate their fire management efforts on the areas around their camps and their tracks through the forest. We could employ a similar strategy which utilises precise cool burns to provide a buffer around our communities and infrastructure. This would minimise the need for frequent landscape scale prescribed burns thereby preserving biodiversity and carbon stores.

Burning problems

: 40 years
Average area of forested land burnt each year in the US increased 1,000% the past 40 years.

: 2.2 billion
In summer 2023, fires in Northern Canada scorched 18.4 million hectares, emitting 2.2 billion tonnes CO2.
: 41%
In Europe in 2023, 470,000 hectares were scorched, with 41% of the burnt area within designated Natura 2000 EU Biodiversity Reservoirs.

: 962 million
In 2015, fires in Indonesia’s forests and peatlands resulted in 962 million tonnes CO2 emissions of carbon emitted and toxic haze spreading across Southeast Asia.
: 30-40%
In the Arctic, wildfires burn the Boreal Forest that stores 30-40% of terrestrial carbon, and scorches the layer of moss, lichen and leaf litter that insulates the frozen permafrost underlaying the region. The melting permafrost releases vast amounts of carbon and methane, leading to a feedback loop of more fires and more melting permafrost.
:
"Zombie fires” are also on the rise in parts of Alaska and Canada. These are fires that come back to life and reignite in the spring when the weather warms up, after smouldering dormant underground during winter.

About the author

Clinton Rakich is Ramboll Australia’s Sustainability Lead in Environment and Health. After 15 years delivering climate services with the Australian Bureau of Meteorology, Clinton is now focussed on the interface between climate and nature risk management. Clinton works with clients to explore integrated and holistic approaches which can be employed to mitigate hazards, increase resilience, and reduce lifecycle costs, particularly through nature-based solutions

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We’re now gripped by the new global phenomenon of megafires – that’s the term used to describe wildfires which are extreme in size, behaviour, and impacts. The most obvious driving factor is climate change.

Burning problems

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