A staggering 1.8 million hectares burned in ‘high-severity’ fires during Australia’s Black Summer


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Ross Bradstock, University of Wollongong; Hamish Clarke, University of Wollongong; Luke Collins, La Trobe University; Michael Clarke, La Trobe University; Rachael Helene Nolan, Western Sydney University, and Trent Penman, The University of MelbourneIn the aftermath of Australia’s devastating Black Summer fires, research has begun to clarify the role of climate change.

We already know climate change contributed to the record-breaking drought and fire weather conditions, leading to the bushfires’ unprecedented range across Australia.

Our new research looks at whether bushfires are becoming more “severe” (an indicator of how intensely the vegetation burned) as a result of climate change.

Our findings were unexpected, as we learned the proportion of high-severity fires generally hasn’t increased in recent decades. However, the sheer breadth of the Black Summer fires meant an unprecedented 1.8 million hectares across southeast Australia were exposed to high-severity fires. This has dire consequences for the people and wildlife who call the forests home.

What is fire severity?

Two measurements in fire science are pertinent to our research: fire severity and fire intensity.

Fire severity refers to how high the flames and the plume of hot air reach, as measured by the resulting damage to vegetation (vertical profile of scorch and consumption of leaves and twigs). Fire intensity refers to the energy released from the fire — how hot and destructive the flames are.

Scientists can estimate severity using using satellite imagery, by contrasting differences in the cover and condition of vegetation before and after fires.

In forests, “high-severity” fires occur when the crowns of dominant trees are fully burnt or scorched. High-severity fires are lethal to tree-dwelling mammals in forests, such as possums, gliders and koalas. They also pose a big risk to nearby homes and buildings.

“Low-severity” fires, on the other hand, may be confined to the leaf litter and ground cover plants beneath the forest canopy, and can even leave entirely unburnt patches in forests.

Are high severity fires becoming more common?

To determine if high-severity bushfires are becoming more common, we looked at satellite data for bushfires from 1988 to 2020. The data covered more than 130,000 square kilometres of forest, woodland and shrubland ecosystems in southeast Australia.

If fires were becoming more intense in recent decades, we would have expected the proportion of vegetation subjected to high-severity fire to have increased.

Instead, we found the average proportion of high-severity wildfire remained constant in dry forest — the dominant vegetation across this region. There was, however, evidence of an increase in the average proportion of high-severity fire in wet forests and rainforests, along with woodlands.




Read more:
5 remarkable stories of flora and fauna in the aftermath of Australia’s horror bushfire season


Nonetheless, the main conclusion was clear: across the bulk of the study area, the average proportion of high-severity fires has not changed in recent decades, despite an increase in the area burned during the Black Summer bushfires.

Why the Black Summer bushfires were exceptional

While the proportion of high-severity fires hasn’t changed, the enormous range of the 2019-2020 bushfires meant 44% of the total area burned by high-severity fire since 1988 occurred in that one summer alone.

This means 1.8 million hectares of the forest and woodland regions of southeastern Australia — an enormous proportion — was exposed to intense and severe fire. In this regard, the Black Summer bushfires were exceptional.

As Australians remember all too clearly, this had a devastating effect on the environment. An estimated three billion animals were killed or displaced, vulnerable rainforests burned and 3,000 homes were destroyed.

A firefighter runs through a burning forest
Firestorms could become more common under a changing climate.
AAP Image/Dean Lewins

The 2019-20 fire season also involved a record number of “firestorms”, particularly during the latter part of the season in January and early February. This occurs when fires create their own weather.

These fires can burn at exceptional intensity. And research from 2019 indicates such firestorms could become more common under climate change.

This means we can’t rule out a future change in the proportion of bushfires that burn at the highest levels of intensity and severity.

Ecosystems in jeopardy

The results of our study underline one of the likely consequences of future climate change.

The sheer scale of the area burned in the 2019-20 fire season exceeded not only historical records for forested ecosystems of southern Australia, but also outstripped projections for the late 21st century under strong scenarios of climate change.




Read more:
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As bushfires become larger in the future, the area exposed to intense and severe fires is likely to increase commensurately. As a result, the future of our wetter forest types, which have not evolved to cope with frequent and severe fires, is in jeopardy.

So, as the area exposed to intense fires is likely to increase in the future, we’ll see major challenges to the long-term viability of our forested ecosystems, the services they provide and the people who reside in and around them.The Conversation

Ross Bradstock, Emeritus professor, University of Wollongong; Hamish Clarke, Research Fellow, University of Wollongong; Luke Collins, Research scientist, La Trobe University; Michael Clarke, Emeritus professor, La Trobe University; Rachael Helene Nolan, Postdoctoral research fellow, Western Sydney University, and Trent Penman, Professor, The University of Melbourne

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

If 80% of Australians care about climate action, why don’t they vote like it?


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Rebecca Colvin, Australian National University and Frank Jotzo, Australian National UniversityPoll after poll suggests a large majority of Australians cares about climate change. Yet in recent federal elections, this hasn’t translated into wins for parties with stronger policy platforms on climate change.

So what determines someone’s climate change attitude, and how does it translate into voting?

In research published today, we studied 2,033 Australian voters’ attitudes across the political spectrum in the context of the 2019 federal election. And we found over 80% said they think it’s important Australia reduce greenhouse gas emissions. This includes close to 70% of conservative voters (those voting for Coalition parties).

However, digging deeper reveals nuance to these attitudes. While most Australians support climate action, stark differences emerge along political party preferences in terms of how important voters think it is.

Our research suggests the question about social support for climate action in Australia is no longer: “does climate change matter to enough Australians?”. Instead, the critical question may well be: “does climate change matter enough to Australians to shift climate politics?”.

Why the ‘climate election’ didn’t pan out

We conducted our survey in July 2019, two months after the Coalition won the federal election. Its victory came as a surprise to many, as the election was sometimes billed the “climate election”, implying climate change was a bellwether issue.

The climate policies of the two major parties were night and day, with the Labor Party campaigning on ambitious mitigation targets and the incumbent Coalition maintaining the status quo of very limited climate policy.

So what were the voters thinking?

We found about half of Australian voters (52%) said climate change was important when deciding their vote in the 2019 Australian federal election. However, climate was the most important issue for only 14% of voters.

Even among those who said they felt it was extremely important for Australia to reduce greenhouse gas emissions, most (58%) said climate change was important, but not the most important issue, when deciding their vote.




Read more:
Australia’s major parties’ climate policies side-by-side


Climate change was stated as the most important issue for 21% of Labor voters and 39% of Greens voters, but for less than 5% of Liberal Party, National Party, and Queensland LNP voters.

This pattern was reversed for those who didn’t take climate change policy into account in their vote: 26% of Liberal, 21% of National, and 31% of Queensland LNP voters did not consider climate change when deciding their vote. Under 15% of Labor and Greens voters did the same.

And when we looked at how much voters cared about climate action, the differences become more potent. Three quarters (73%) of progressive voters (those voting for the ALP or the Greens) see Australian action to reduce emissions as “extremely important”. Only one quarter (26%) of conservative voters say the same thing.



Who’s more willing to make sacrifices for the climate?

Our research also explored the extent voters were willing to accept a personal cost to support climate action. We asked about their willingness to accept a significant or small personal cost, but didn’t specify what we meant by small or significant, because a small cost to one person may be a significant cost to another.

Most voters (72%) said they’d be willing to incur some personal cost in return for emissions reductions. Across the political spectrum, the proportion of voters willing to accept a small personal cost is relatively similar: 60% of progressive voters, 55% of conservative voters.



Major differences emerge when it comes to “significant personal cost”.

While 26% of progressive voters are willing to incur a significant personal cost, only 5% of conservative voters feel similarly. At the other end of the spectrum, 40% of conservative voters are unwilling to incur any personal cost, but only 14% of progressive voters feel the same.

Support for strong climate policies may depend on whether the policies will, or are perceived to, personally impact voters. Given political leaders’ stances influence public support for climate policies (as 2018 research showed), our research highlights an opportunity for conservative political leaders to clarify their position on climate change.



Interestingly, age was a consistent predictor of responses. Younger people were more likely than older people to consider it important that Australia reduce greenhouse gas emissions. Younger people were more willing to incur a personal cost to support climate action, and to consider climate change when deciding their vote.

In fact, we found an Australian voter from the Baby Boomer generation is half as likely as a voter from Generation Z to consider it important to reduce greenhouse gas emissions.

Divisive politics have a limited shelf life

If future young people cared just as much about climate change as today’s young people, and if existing cohorts don’t change their views as they age, then the percentage of Australian voters who consider greenhouse gas emissions to be “extremely important” is likely to increase from 52% in our 2019 data, to 56% by 2030. By 2050, this figure could rise to 65%.



These projections are purely on the basis of more climate-aware cohorts coming into voting age and replacing older voters. It doesn’t consider any future changes in attitudes within cohorts (which may also make a big difference).

The key implication is simple. If Australian political leaders pursued stronger climate action, they could rest assured most of the voting population will broadly support them, along with most of their own voter base — regardless of which party is in power.

This will become only more pronounced with gradual generational change, and likely changes in attitudes within age groups. In any case, it’s clear divisive politics that result in climate delay have a limited shelf life.




Read more:
Nearly 80% of Australians affected in some way by the bushfires, new survey shows


The Conversation


Rebecca Colvin, Senior lecturer, Crawford School of Public Policy, Australian National University and Frank Jotzo, Director, Centre for Climate and Energy Policy, Australian National University

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

The European Union wants to impose carbon tariffs on Australian exports. Is that legal?


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Felicity Deane, Queensland University of TechnologyWhat Australian politicians call carbon tariffs, the European Union labels a carbon border adjustment mechanism.

While one sounds bad (the World Trade Organisation has rules that restrict tariffs) the other sounds understandable — if the European Union is imposing a carbon tax on its own products as Australia once did, surely it is reasonable to impose it on products from overseas.

The argument is that if a German steel manufacturer has to pay a tax of, say, $77 a tonne for the carbon it emits while making the steel, an Australian manufacturer should be charged the same when its product enters the country, unless it has already paid the same tax here.

To do otherwise would give the Australian product an unfair price advantage — it would create “carbon leakage” of the kind Australian businesses used to warn about in the leadup to Australia’s carbon price.

The European Union approved the idea in principle on March 10.

The details are less than clear, in part because it is possible that carbon tariffs are not permitted under the rules of the World Trade Organisation to which European nations and most other nations belong.

WTO rules might help Australia…

The rules say taxes or “charges of any kind” can only be imposed on imported products the same way as they are domestically.

That appears to mean that they can be imposed on importers but not on producers, which isn’t quite what the European Union has in mind.

Ideally the World Trade Organisation would be able to provide guidance, but (in part because of the actions of the US Trump administration) it isn’t really in a position to do.

…if only they were enforceable

New World Trade Organisation director general Ngozi Okonjo-Iweala.
Fabrice Coffrini/AP

The WTO has a new director general in Ngozi Okonjo-Iweala who took office this month, but it will remain in an “induced coma” for as long as its appellate body is unable to hear disputes.

Under Trump, the US kept vetoing appointments to the appellate body until the expiration of terms of its existing members meant it no longer had a quorum.

Disputes can still be initiated by countries such as Australia, forcing consultations, but without final determinations.

Although the European Union says it wants to ensure that its adjustment mechanism complies with the WTO’s rules, it hasn’t ruled out the possibility of relying on provisions that allow exceptions.

Both sides could make a case

Exceptions are allowed for the protection of human, animal or plant life or health or the protection of an exhaustible natural resource.

The catch is these exceptions are not allowed to discriminate between countries and must not be disguised restrictions on trade.

It is arguable that an adjustment mechanism designed to protect the competitiveness of European industries will breach these provisions.




Read more:
No point complaining about it, Australia will face carbon levies unless it changes course


The European Union has suggested that border adjustments will be unnecessary when the rest of the world has matched it in committing to achieve net zero emissions by 2050, so long as these commitments are back up by real actions.

But that hasn’t happened yet, and despite talk by Prime Minister Scott Morrison of his “hope” that Australia can get to net zero by 2050, Australia hasn’t made a commitment, and hasn’t backed it with tax-like instrument.

With any World Trade Organisation determination uncertain and perhaps impossible, apart from complaining about carbon tariffs or border adjustments, there may be little Australia can do.The Conversation

Felicity Deane, Associate Professor, Queensland University of Technology

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

Yes, Australia is a land of flooding rains. But climate change could be making it worse


Etching of the 1867 flood in the Hawkesbury-Nepean Valley, depicting the Eather family.
illustrated Sydney News/author provided

Joelle Gergis, Australian National UniversityOver the past three years, I’ve been working on the forthcoming report by the United Nations’ Intergovernmental Panel on Climate Change. I’m a climate scientist who contributed to the chapter on global water cycle changes. It’s concerning to think some theoretical impacts described in this report may be coming to life – yet again – in Australia.

The recent flooding in New South Wales is consistent with what we might expect as climate change continues.

Australia’s natural rainfall patterns are highly variable. This means the influence climate change has on any single weather event is difficult to determine; the signal is buried in the background of a lot of climatic “noise”.

But as our planet warms, the water-holding capacity of the lower atmosphere increases by around 7% for every 1℃ of warming. This can cause heavier rainfall, which in turn increases flood risk.

The oceans are also warming, especially at the surface. This drives up both evaporation rates and the transport of moisture into weather systems. This makes wet seasons and wet events wetter than usual.

So while Australia has always experienced floods, disasters like the one unfolding in NSW are likely to become more frequent and intense as climate change continues.

People watch swollen river
Flooding is likely to become more severe as the planet warms.
AAP

Understanding the basics

To understand how a warming world is influencing the water cycle, it’s helpful to return to the theory.

From year to year, Australia’s climate is subject to natural variability generated by the surrounding Pacific, Indian and Southern oceans. The dominant drivers for a given year set up the background climate conditions that influence rainfall and temperature.

It is a combination of these natural climate drivers that makes Australia the land of drought and flooding rains.

However, Australia’s climate variability is no longer influenced by natural factors alone. Australia’s climate has warmed by 1.4℃ since national records began in 1910, with most of the warming occurring since 1970. Human-caused greenhouse emissions have influenced Australian temperatures in our region since 1950.

This warming trend influences the background conditions under which both extremes of the rainfall cycle will operate as the planet continues to warm. A warmer atmosphere can hold more moisture (higher water vapour content), which can lead to more extreme rainfall events.

A warmer atmosphere can hold more moisture which can lead to more extreme rainfall events.
Climate Council

Since the winter of 2020, Australia has been influenced by the La Niña phase of the El Niño–Southern Oscillation (ENSO). Historically, sustained La Niña conditions, sometimes with the help of a warmer than average Indian Ocean, have set the scene for severe flooding in eastern Australia.

During these events, easterly winds intensify and oceans around Australia warm. This is associated with the Walker Circulation – a giant seesaw of atmospheric pressure that influences the distribution of warm ocean waters across the Pacific Ocean.

The last La Niña occurred in 2010–2012. It led to widespread flooding across eastern Australia, with particularly devastating effects in Queensland. The event caused the wettest two-year period in the Australian rainfall record, ending the 1997–2009 Millennium Drought.

Oceanographers from UNSW studied the exceptional event. They demonstrated how a warmer ocean increased the likelihood of extreme rain during that event, primarily through increased transport of moist air along the coast.

Their analysis highlighted how long‐term ocean warming can modify rain-producing systems, increasing the probability of extreme rainfall during La Niña events.

It is important to point out that changes in large-scale atmospheric circulation patterns are still not as well understood as fundamental changes in thermodynamics. However, because regional rainfall changes will be influenced by both factors, it will take researchers time to tease everything out.

So what about climate change?

The theoretical changes to the global water cycle are well understood. However, determining the contribution of natural and human influences on climate variability and extremes – known as “attribution” – is still an emerging science.

More studies are needed to distinguish natural or “background” rainfall variability from recent human-caused changes to the water cycle. This is particularly the case in a country like Australia, which has very high yearly rainfall variability. This contrasts with some regions of the Northern Hemisphere with less variable rainfall, where a clear climate change signal has already emerged.

Right now, La Niña conditions are decaying in the Pacific Ocean. As expected, the 2020–2021 La Niña has brought above-average rainfall to much of eastern Australia. This helped ease the severe drought conditions across eastern Australia since 2017, particularly in NSW.

NSW rainfall total, week ending March 22, 2021
NSW rainfall totals for the week ending March 22, 2021.
Bureau of Meteorology

What’s interesting about the 2020–2021 La Niña is that it was weak compared with historical events. The relationship between La Niña and rainfall is generally weaker in coastal NSW than further inland. However, it’s concerning that this weak La Niña caused flooding comparable to the iconic floods of the 1950s and 1970s.

The rainfall totals for the current floods are yet to be analysed. However, early figures reveal the enormity of the downpours. For example, over the week to March 23, the town of Comboyne, southwest of Port Macquarie, recorded an extraordinary 935mm of rainfall. This included three successive days with more than 200mm.

The NSW coast is no stranger to extreme rainfall – there have been five events in the past decade with daily totals exceeding 400mm. However, the current event is unusual because of its duration and geographic extent.

It’s also worth noting the current extreme rainfall in NSW was associated with a coastal trough, not an East Coast Low. Many of the region’s torrential rainfall events in the past have resulted from East Coast Lows, although their rainfall is normally more localised than has been the case in this widespread event.

Remember that as the air warms, its water-holding capacity increases, particularly over the oceans. Current ocean temperatures around eastern and northern Australia are about 1℃ warmer than the long-term average, and closer to 1.5℃ warmer than average off the NSW coast. These warmer conditions are likely to be fuelling the systems driving the extreme rainfall and associated flooding in NSW.

Sea surface temperature anomalies along the NSW coast.
Bureau of Meteorology

A nation exposed

Weather and climate are not the only influences on extreme flood events. Others factors include the shape and size of water catchments, the presence of hard surfaces in urban areas (which cant’t absorb water), and the density of human settlement in flood-prone areas.

The Hawkesbury–Nepean region in Western Sydney, currently experiencing major flooding, is a prime example. Five major tributaries, including the Warragamba and Nepean Rivers, flow into this extensively urbanised valley.

Improving our understanding of historical weather data may help improve future climate change risk assessment. For example, past floods in the Hawkesbury–Nepean have been a lot worse than the current disaster. In 1867, the Hawkesbury River at Windsor reached 19.7 metres above normal, and in 1961 peaked at 14.5 metres. This is worse than the 13.12 metres above normal recorded at Freemans Reach on March 23.

It’s sobering to think the Hawkesbury River once peaked 6 metres higher than what we’re seeing right now. Imagine the potential future flooding caused by an East Coast Low during strong La Niña conditions.

It will take time before scientists can provide a detailed analysis of the 2020–2021 La Niña event. But it’s crystal clear that Australia is very exposed to damage caused by extreme rainfall. Our theoretical understanding of water cycle changes tells us these events will only become more intense as our planet continues to warm.The Conversation

Joelle Gergis, Senior Lecturer in Climate Science, Australian National University

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