The sweet relief of rain after bushfires threatens disaster for our rivers



After heavy rainfall, debris could wash into our waterways and threaten fish, water bugs, and other aquatic species.
Jarod Lyon, Author provided

Paul McInerney, CSIRO; Gavin Rees, CSIRO, and Klaus Joehnk, CSIRO

When heavy rainfall eventually extinguishes the flames ravaging south-east Australia, another ecological threat will arise. Sediment, ash and debris washing into our waterways, particularly in the Murray-Darling Basin, may decimate aquatic life.

We’ve seen this before. Following 2003 bushfires in Victoria’s alpine region, water filled with sediment and debris (known as sediment slugs) flowed into rivers and lakes, heavily reducing fish populations. We’ll likely see it again after this season’s bushfire emergency.




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Large areas of northeast Victoria have been burnt. While this region accounts only for 2% of Murray-Darling Basin’s entire land area, water flowing in from northeast Victorian streams (also known as in-flow) contributes 38% of overall in-flows into the Murray-Darling Basin.

Fire debris flowing into Murray-Darling Basin will exacerbate the risk of fish and other aquatic life dying en masse as witnessed in previous years..

What will flow into waterways?

Generally, bushfire ash comprises organic carbon and inorganic elements such as nitrogen, phosphorous and metals such as copper, mercury and zinc.

Sediment rushing into waterways can also contain large amounts of soil, since fire has consumed the vegetation that once bound the soil together and prevented erosion.

And carcinogenic chemicals – found in soil and ash in higher amounts following bushfires – can contaminate streams and reservoirs over the first year after the fire.

A 2014 post-fire flood in a Californian stream.

How they harm aquatic life

Immediately following the bushfires, we expect to see an increase in streamflow when it rains, because burnt soil repels, not absorbs, water.

When vast amounts of carbon are present in a waterway, such as when carbon-loaded sediments and debris wash in, bacteria rapidly consumes the water’s oxygen. The remaining oxygen levels can fall below what most invertebrates and fish can tolerate.

These high sediment loads can also suffocate aquatic animals with a fine layer of silt which coats their gills and other breathing structures.

Habitats are also at risk. When sediment is suspended in the river and light can’t penetrate, suitable fish habitat is diminished. The murkier water also means there’s less opportunity for aquatic plants and algae to photosynthesise (turn sunshine to energy).




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How wildfire smoke affects pets and other animals


What’s more, many of Australia’s waterbugs, the keystone of river food webs, need pools with litter and debris for cover. They rely on slime on the surface of rocks and snags that contain algae, fungi and bacteria for food.

But heavy rain following fire can lead to pools and the spaces between cobbles to fill with silt, causing the waterbugs to starve and lose their homes.

This is bad news for fish too. Any bug-eating fish that manage to avoid dying from a lack of oxygen can be faced with an immediate food shortage.

Many fish were killed in Ovens River after the 2003 bushfires from sediment slugs.
Arthur Rylah Institute, Author provided

We saw this in 2003 after the sediment slug penetrated the Ovens River in the north east Murray catchment. Researchers observed dead fish, stressed fish gulping at the water surface and freshwater crayfish walking out of the stream.

Long-term damage

Bushfires can increase the amount of nutrients in streams 100 fold. The effects can persist for several years before nutrient levels return to pre-fire conditions.

More nutrients in the water might sound like a good thing, but when there’s too much (especially nitrogen and phosphorous), coupled with warm temperatures, they can lead to excessive growth of blue-green algae. This algae can be toxic to both people and animals and often closes down recreational waters.




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Large parts of the upper Murray River catchment above Lake Hume has burnt, risking increases to nutrient loads within the lake and causing blue-green algae blooms which may flow downstream. This can impact communities from Albury all the way to the mouth of the Murray River in South Australia.

Some aquatic species are already teetering on the edge of their preferred temperature as stream temperatures rise from climate change. In places where bushfires have burnt all the way to the stream edge, decimating vegetation that provided shade, there’ll be less resistance to temperature changes, and fewer cold places for aquatic life to hide.

Cooler hide-outs are particularly important for popular angling species such as trout, which are highly sensitive to increased water temperature.

Ash blanketing the forest floor can end up in waterways when it rains.
Tarmo Raadik

But while we can expect an increase in stream flow from water-repellent burnt soil, we know from previous bushfires that, in the long-term, stream flow will drop.

This is because in the upper catchments, regenerating younger forests use more water than the older forests they replace from evapotranspiration (when plants release water vapour into the surrounding atmosphere, and evaporation from the surrounding land surface).

It’s particularly troubling for the Murray-Darling Basin, where large areas are already enduring ongoing drought. Bushfires may exacerbate existing dry conditions.

So what can we do?

We need to act as soon as possible. Understandably, priorities lie in removing the immediate and ongoing bushfire threat. But following that, we must improve sediment and erosion control to prevent debris being washed into water bodies in fire-affected areas.




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In fact, there’s plenty we can do to make future fires less likely


One of the first things we can do is to restore areas used for bushfire control lines and minimise the movement of soil along access tracks used for bushfire suppression. This can be achieved using sediment barriers and other erosion control measures in high risk areas.

Longer-term, we can re-establish vegetation along waterways to help buffer temperature extremes and sediment loads entering streams.

It’s also important to introduce strategic water quality monitoring programs that incorporate real-time sensing technology, providing an early warning system for poor water quality. This can help guide the management of our rivers and reservoirs in the years to come.

While our current focus is on putting the fires out, as it should be, it’s important to start thinking about the future and how to protect our waterways. Because inevitably, it will rain again.The Conversation

Paul McInerney, Research scientist, CSIRO; Gavin Rees, , CSIRO, and Klaus Joehnk, Senior research scientist, CSIRO

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

Bushfires won’t change climate policy overnight. But Morrison can shift the Coalition without losing face



When polling resumes after the summer, Scott Morrison may be surprised by the public’s assessment of his government’s handling of the bushfires.
Mick Tsikas/AAP

Chris Wallace, Australian National University

The hope of many people enduring this summer’s firestorms is that better climate policy will arise phoenix-like from the ashes.

It is expressed loudly, fervently, sometimes abusively by people directly affected and those feeling solidarity with them.

It is also expressed secretly, whispered to like-minded confidants, by others who are part of or allied with the Liberal-National (LNP) coalition government of Prime Minister Scott Morrison.

On Sunday, Morrison indicated that he would take a proposal to establish a royal commission into the bushfires to his Cabinet.

But when it comes to climate policy, there are three possible scenarios in the aftermath of the crisis: everything magically changes for the better, everything stays the same or something different happens.

What these three scenarios look like

Everything magically changes for the better would look like this: Morrison announces the crisis has transformed his previous token admission of a link between bushfires and climate change into a revelation of the reality of global warming, with consequential policy change.

As logical and desirable as this seems, it is unlikely, not least because of Morrison’s character and personal beliefs.

Everything stays the same has a powerful impetus behind it. Morrison does not want policy change any more than his likely successor in the event of leadership change, Peter Dutton.




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Government-friendly journalists and commentators at News Corp and 2GB show no sign of changing tack either, so even if the government wanted to shift its policy, the media environment makes it difficult to do so. The forces of inertia are powerful.

Then there is the slim hope that something different happens. This scenario relies on all three of Australia’s main political groupings – the LNP, Labor and the Greens – realising they each face their own distinct climate policy challenge and rising to it.

As Australian burns, its politicians squabble over who’s to blame and how to prevent future disasters.
David Mariuz/AAP

Avoiding the appearance of a backflip

Opinion polls are not done over the summer holiday period, meaning the LNP has yet to see the impact of the bushfires on their public standing.

When polling resumes, Liberal and National MPs will understand the impact, and they won’t like it. Morrison and others will likely urge party members to hold their course since the next election is years away and a dozen other issues could distract attention from climate policy between now and then.

This tactic can prevail for some time but is not strategically sustainable: firestorms like those in the summer of 2020 will not be the last.




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The emerging LNP argument that inadequate hazard reduction burns are to blame for the current crisis is risible. The Australian who has emerged with the most credibility from the bushfires – NSW Rural Fire Service Commissioner Shane Fitzsimmons – rejects it out of hand.

The LNP’s challenge, then, is to realise its current position won’t hold strategically and to transition to better policy ahead of that becoming obvious, managing the optics to avoid the appearance of a backflip.

The challenge for Labor and the Greens

Labor is benefiting from leader Anthony Albanese’s call for “an adult conversation” in Australia about climate policy. He is astutely citing British Tories like the late Margaret Thatcher and current Prime Minister Boris Johnson, who long ago accepted and acted upon the climate science the Morrison government viscerally rejects.

Labor’s homework now is to reconcile the views and interests of members and supporters prioritising climate policy over mining jobs, and vice versa.

This can and must be done if Labor is to build a coalition of support big enough to win office and then enact the climate and other policies the current firestorms make so urgent.




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The Greens, meanwhile, need to have an internal conversation about whether they want to continue making perfect policy the enemy of the good – leaving Australia with no emissions trading system (ETS) at all, for example, because they would not vote for one that did not meet their every demand – or join in efforts to begin on the path to better policy.

Central to that conversation must be a realisation their current strategy isn’t working – the LNP keeps returning to power.

Greens leader Richard Di Natale has said the bushfires should be a
David Crosling/AAP

A possible way forward

There is an obvious point the LNP, Labor and Greens might momentarily agree upon to move policy forward. It is the ETS proposed by Liberal Prime Minister John Howard in 2007.

Howard saw climate change coming. In late 2006, he established a prime ministerial task group on emissions trading chaired by the secretary of his Department of Prime Minister and Cabinet, Peter Shergold.

The Shergold Report, released in May 2007, said “emissions trading should be preferred to a carbon tax” and among the various kinds possible, a national “cap and trade” ETS was best.

In an address to the Liberal Party Federal Council in October 2007, Howard promised to establish a national ETS starting no later than 2012.

This will be a world-class emissions trading system more comprehensive, more rigorously grounded in economics and with better governance than anything in Europe.

Implementing an emissions trading scheme and setting a long-term goal for reducing emissions will be the most momentous economic decisions Australia will take in the next decade.

This emissions trading system must be built to last. It needs to last not five or 10 years, it needs to last the whole of the 21st century if Australia is to meet our global responsibilities and further build our economic prosperity.

Howard positioned the LNP as the party Australians could trust to implement an ETS in a way that gives “firms and families” the ability to “plan for the future with confidence”.

His authorship – and his framing of his ETS as an act of economic responsibility –provides a fig leaf Morrison can now use to move the LNP to a credible, sustainable and politically viable climate policy position.

“Something different” has to start somewhere. If Morrison can deploy the cunning he showed winning the 2019 election by drawing on Howard’s deep well of credibility within the LNP to implement the plan himself and then inviting – daring – Labor and the Greens to back him, it would be a signal political achievement.

And if Morrison doesn’t want to, Labor, the Greens, independent MPs and conscientious LNP MPs should vote together to turn Howard’s ETS into law right away. With political will, “something different” can start now.


Updates to add that the latest Newspoll, released late Sunday, shows Morrison’s standing has taken a massive hit over the bushfires, dropping nine percentage points as preferred prime minister from 48% to 39% since the last poll in early December. Opposition leader Anthony Albanese stood at 43% – a massive reversal of Morrison’s 14 percentage point lead over the Labor leader in early December.The Conversation

Chris Wallace, ARC DECRA Fellow, Australian National University

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

Even for an air pollution historian like me, these past weeks have been a shock



Throughout history, Australian bushfires have spread smoke over our cities. But this time it’s different.
David Mariuz/AAP

Nancy Cushing, University of Newcastle

Smoke from this season’s bushfires has turned the sun red, the moon orange and the sky an insipid grey. It has obscured iconic views tourists flock to see. Far more than an aesthetic problem, it has forced business shutdowns, triggered health problems and kept children indoors for weeks.

City dwellers in southeast Australia have been forced to take a crash course in the finer points of air pollution. We’ve learned about the dangers of inhaling tiny PM2.5 particles (those 2.5 microns or fewer in diameter). We’ve learned that only a close-fitting P2 mask will do much to protect us.

Still, we wear disposable paper masks and hold handkerchiefs to our faces, hoping any amount of filtering is helpful.

A police officer wears a mask while on duty at Parliament House in Canberra.
NARENDRA SHRESTHA/AAP

Even for an historian of air pollution like me, this situation is a shock. It is not the first time Australia’s major cities have been shrouded in bushfire smoke. But the terrible air quality is unmatched in terms of severity, duration and extent.

Historically, air pollution from smoke was considered outside human control and not subject to regulation. But these bushfires are clearly linked to global warming, for which government, corporations and individuals are responsible. It’s time to rethink the way we protect air quality.

The history of smoke

In recent weeks, apps such as AirVisual have confirmed what we city dwellers can already see and smell: since the fires on the north coast of NSW began in late October, our air quality has plummeted.

The New South Wales government’s Air Quality Index data has shown that since late October, days when the index was higher than 100 – signalling exposure is unhealthy – have outnumbered clear days in Sydney, Newcastle and the Illawarra.

Smoke emissions from the Australian bushfires from 1 December 2019 to 4 January 2020.

Index readings above 2,550 have been recorded in Sydney, while the Monash monitoring site in Canberra reached a choking 5,185 at 8pm on New Year’s Day.

Bushfire smoke has affected the cities of NSW and the Australian Capital Territory in the past. In late January 1926, when Canberra was just emerging as a city, a thick haze of smoke sat over the site. Fires came within metres of Yarralumla, the residence which, the following year, would become home to the Governor-General.

In several years in the mid 1930s, bushfires burning to the north of Sydney left the city air thick with smoke. In October 1936, bushfire smoke forced a motor liner arriving from Hong Kong to warily enter the harbour sounding its siren, because it was invisible to signallers on South Head.

A New Zealand pilot, flying into Sydney from Longreach the following month, had to fly blind in “great clouds of dense smoke” covering much of NSW. In 1939, Canberra was covered by what visiting writer HG Wells described as a “streaming smoke curtain”.




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In the summer of 1944, Sydney was again enveloped in a smoke haze, this time from fires in the Blue Mountains and (later Royal) National Park in November. Photographs published at the time show the Sydney Harbour Bridge barely visible through dust and smoke at midday. The ongoing fires were blamed for an increase in diseases of the ears, nose and throat, and for cases of influenza and pneumonia, leading to a shortage of hospital beds.

A satellite image showing fires burning on Australia’s east coast.
NASA EARTH OBSERVATORY

In November 1951, all of NSW was said to be blacked out by bushfire smoke. In Sydney on the worst days, records show all four of the city’s airfields were closed because of “smoke-fog”.

A hazy legal framework

In each of these episodes, bushfire smoke disrupted transport, commerce, health and the enjoyment of the urban environment. But even as other forms of air pollution began to be regulated, smoke from bushfires escaped legislative attention.

What was understood as air pollution were the unwanted byproducts of industrial processes, whereas bushfire smoke was viewed as natural.




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In NSW in 1866, an act based on British legislation restricted smoke from mills, distilleries and gas works. Further limitations on smoke production in built-up areas were included in later acts governing public health (1902), motor traffic (1909) and local government (1919).

After World War II Newcastle, the site of the country’s largest concentration of coal-burning heavy industry, began to pay closer attention to managing air quality. This pioneering work was given added urgency after 4,000 people died in heavy London smog in 1952.

A woman seen wearing a face mask as smoke haze from bushfires blankets Sydney.
JOEL CARRETT/AAP

In 1958, a NSW parliamentary committee delivered a report into smoke abatement. It did not mention recent issues with bushfire smoke, and also dismissed the impact of domestically produced smoke. The subsequent 1961 Clean Air Act focused on air pollution from industry, transport and power generation.

Air pollution legislation continued to evolve in following decades, targeting motor vehicle emissions in the 1970s, backyard burning of waste in the 1980s, and wood fires used to heat homes in the 1990s.

These measures have been successful. A 2006 study found that between 1998 and 2003, on the limited occasions when standards for PM10 in six Australian cities were exceeded, the main sources were not industry or transport, but dust storms and bushfires (with the exception of Launceston, where heating fires were the main contributor).

A young man jumps from a rock in Sydney during smoke haze.
Steven Saphore/AAP

Looking ahead

Today, bushfire smoke is excluded from air quality regulations, despite its obvious role in pollution. It is still considered natural, and beyond human control.

However the link between the current fires and human-caused climate change, long predicted by climate scientists, suggests this exemption is no longer valid.




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As the Australian National University’s Tom Griffiths has written, the current fires in some ways repeat patterns of the past. But “the smoke is worse, more widespread and more enduring”.

When Australia begins the recovery from these fires, our business-as-usual approach requires a rethink. Measures to protect air quality should be a major part of this.

It is time that corporations, governments and societies which contribute to global heating be held to account for more frequent, intense and widespread bushfires, and the smoke which billows from them.The Conversation

Nancy Cushing, Associate professor, University of Newcastle

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