Australia’s pristine beaches have a poo problem



Raw sewage from 3,500 people in Sydney’s affluent eastern suburbs is discharged directly into the ocean.
Will Turner/Unsplash

Ian Wright, Western Sydney University; Andrew Fischer, University of Tasmania; Boyd Dirk Blackwell, University of Tasmania; Qurratu A’yunin Rohmana, University of Tasmania, and Simon Toze, CSIRO

Australians love our iconic coastal lifestyle. So many of our settlements are spread along our huge coastline. Real estate prices soar where we can catch a view of the water.

But where there are crowded communities, there is sewage. And along the coast it brings a suite of problems associated with managing waste, keeping the marine environment healthy, and keeping recreational swimmers safe.




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Sewage is not a sexy topic. People often have an “out of sight, out of mind” attitude. But where does sewage go, and is it treated and disposed of in the waters that we Australians love?

The bigger the coastal community, the bigger the volume of sewage. Disposal of human waste into the ocean might solve one problem, but we now realise that the “waste” is as precious as the ocean it pollutes.

We should be treating and recycling sewage to a drinkable level.
shutterstock

Understanding the problem from a national perspective

Such problems play out continuously along our coastline. Each isolated community and catchment issue arises and is resolved, often in ignorance of and isolation from similar issues somewhere else.

At present, places where sewage impacts are generating community concern include Merimbula, Warrnambool and, perhaps most bizarrely, Vaucluse and Diamond Bay in Sydney’s affluent eastern suburbs.

It’s hard to believe this location has raw and untreated sewage from 3,500 people discharged directly into the Tasman Sea. Sydney Water pledged in 2018 to fix this unsightly pollution by transferring the flow to the nearby Bondi sewage treatment plant.

Community group Clean Ocean Foundation has worked with the Marine Biodiversity Hub to start the process of viewing outfall pollution – where a drain or sewer empties into the sea – as part of a bigger picture. It’s a first step towards understanding from a national perspective.




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Together they have produced the National Outfall Database to provide the first Australia-wide comparison.

The best and worst offenders

Previously the information available to the public was sketchy and often not easily accessed. The database shows how differently Australia manages coastal sewage with information on the outfalls.

Clean Ocean Foundation CEO John Gemmill said:

Water authorities in the main do a great job with severe funding constraints. But they can be reticent to divulge information publicly.

One authority, suspicious of the research project, initially refused to give the location of the outfall, claiming it would be vandalised by enraged “surfies and fishermen”.

Sydney has Australia’s biggest outfall. It provides primary treatment at Malabar, New South Wales, and serves about 1.7 million people. The outfall releases about 499 megalitres (ML) per day of treated sewage, called “effluent”.

That’s about eight Olympic-sized swimming pools of effluent an hour. It is discharged to the Pacific Ocean 3.6 kilometres from the shoreline at a depth of 82 metres.

The cleanest outfall (after sustained advocacy over decades from the Clean Ocean Foundation) is Boags Rock, in southern Melbourne. It releases tertiary-treated sewage with Class A+ water. This means the quality is very suitable for reuse and has no faecal bacteria detected (Enterococci or E.coli).

Recycling sewage

Treated sewage is 99% water. The last 1% is what determines if the water will harm human and environmental health. Are we wasting a precious resource by disposing of it in the ocean?

As desalination plants are cranking up in Sydney and Melbourne to extract pure water from salty ocean, why shouldn’t we also recycle sewage?




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Clean Ocean Foundation has released a report showing it would pay to treat sewage more thoroughly and reuse it. This report finds upgrading coastal sewage outfalls to a higher level of treatment will provide tens of billions of dollars in benefits.

Industry analysis suggests that, for a cost outlay of between A$7.3 billion and A$10 billion, sewage treatment upgrades can deliver between A$12 billion and A$28 billion in net benefits – that is, the financial benefits above and beyond what it cost to put new infrastructure in place.

Then there are non-economic benefits such as improved ecological and human health, and improved recreational and tourism opportunities by use of suitable recycling processes.

What the rest of Australia can learn from WA

Clean Ocean Foundation president Peter Smith said Australia’s key decision-makers now, more than before, have a “golden opportunity” to adopt a sea change in water reform around coastal Australia based on good science and sound economic analysis.

In the context of the drought of southeast Australia, recycling water from ocean outfalls is an option that demands further debate.




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As expensive desalination plants are switched on, Sydney proposes to double the size of its desalination plant – just a few kilometres from massive ocean outfalls that could provide so much recycled water. And to our shame, NSW ocean outfalls are among the lowest in standards of treatment.

Western Australia, on the other hand, leads the push to recycle wastewater as it continues to struggle with diminishing surface water from climate change.

In fact, in 2017 the Water Corporation announced massive investment in highly treated sewage being used to replenish groundwater supplies. Perth now sources 20% of its drinking water from groundwater, reducing its reliance on two desalination plants. A key factor was successful engagement with affected communities.

The discharge of poorly treated sewage to rivers, estuaries and oceans is a matter of national environmental significance and the Commonwealth should take a coordinating role.

Our oceans do not respect state boundaries. The time is ripe for a deliberate national approach to recycling sewage and improved systems to manage outfalls.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University; Andrew Fischer, Senior Lecturer, University of Tasmania; Boyd Dirk Blackwell, Adjunct Researcher, University of Tasmania; Qurratu A’yunin Rohmana, Research Analyst, University of Tasmania, and Simon Toze, Senior Principal Research Scientist, CSIRO

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

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We asked people to do climate change maths. Their answers depended on their politics


Will J Grant, Australian National University

In an ideal world, people would look at issues with a clear focus only on the facts. But in the real world, we know that doesn’t happen often.

People often look at issues through the prism of their own particular political identity – and have probably always done so.

However, in an environment of fake news, filter bubbles and echo chambers, it seems harder than ever to get people to agree about simple facts.

In research published today in Environmental Communication, my colleague Matthew Nurse and I report that even some of the smartest among us will simply refuse to acknowledge facts about climate change when we don’t like them.




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Skin cream versus climate change

The research took place just before Australia’s 2019 federal election.

We asked 252 people who were planning to vote for the Greens and 252 people who were planning to vote for One Nation to consider some data we’d put together. To understand that data, they would need to do some mental maths, just like you would when looking at a typical scientific report.

While there was no significant difference in the mathematical ability between the two groups of voters overall, it seemed that political affiliations can have an impact on how people answered a mathematical question, depending on the subject.

For example, in one experiment we told participants that data in the scientific report was about whether a new skin cream would cure a rash, as shown below.

We asked them to indicate whether the experiment shows that using the new cream is more likely to make the skin condition better or worse. Participants in our study got the correct mathematical answer 48% of the time.

However, when we showed them exactly the same data but said it was about whether closing coal-fired power stations would significantly reduce carbon dioxide emissions in the local area (by 30% or more), we got a very different set of answers.

For example, when the report showed CO₂ emissions would go down significantly, only 27% of One Nation supporters got the right answer.

When the report showed CO₂ emissions would not significantly go down, only 37% of Greens voters got it right.

So it seems our participants were less likely to answer a question correctly when it went against their political ideology.




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Spilt people according to maths ability

But what follows is really the interesting bit.

We decided to find out whether numeracy – maths ability – played a role in people getting the wrong answers. First, we looked at those with below-average numeracy.

We found many of these people just gave their preferred, ideologically aligned answers when it came to the climate change question. This is a well-known effect called motivated reasoning.

But surely the more numerate groups of people, those better at maths, would fare better? Well, not really.

The groups of people with above-average numeracy sometimes did worse than the less numerate groups. Some did no better than chance at 50%, and some did far, far worse than that, as the graph below shows.

More numerate people are more polarised about climate change data.
Matt Nurse, Author provided

When we showed people reports about CO₂ emissions, the more numerate people were much more politically polarised than any other group. For example, the participants considered a report showing that CO₂ would go down significantly, a One Nation supporter with a numeracy score of seven (out of nine) was only 5% as likely to provide the correct answer as a Greens supporter in the same numeracy category.

Motivations change brain function

This is counterintuitive, but this isn’t the first study to reveal this effect.

These findings build on research previously done by a Yale professor, Dan Kahan. The phenomenon is a type of motivated reasoning called motivated numeracy.

While Kahan’s previous research focused on the politically polarising issue of gun control in the United States, some people suggested the same thing might happen with other topics, particularly climate change.




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Our research is the first to confirm this.

These findings build on the theory that your desire to give an answer in line with your pre-existing beliefs on climate change can be stronger than your ability or desire to give the right answer.

In fact, more numerate people may be better at doing this because they are have more skills to rationalise their own beliefs in the face of contradictory evidence.

So what?

You might ask whether it really matters if people sometimes get the wrong answer on questions like this.

We’d argue yes, it does matter. Successful democracies rely on a majority of voters being able to identify and understand risks, and make the appropriate voting choices.

If people remain entrenched in their ideological corners when threats come along, and are unwilling to face facts, societal problems can fester, potentially becoming much more difficult to resolve later.

Just imagine scientists had discovered human activity was damaging our atmosphere. They said this problem would cause Earth’s climate to get hotter and threaten our livelihoods. Politicians and the people they represented saw this as a legitimate issue worth acting on, regardless of their political views. Imagine the world united to fix this problem, even though it would cost a lot of money.

In fact, we don’t need to imagine too much, as this isn’t just a hypothetical situation. It actually happened when scientists found evidence the use of industrial chemicals was depleting the ozone layer.

In 1987, for the first and only time, all 197 members of the United Nations agreed to sign the Montreal Protocol regulating the man-made chemicals that destroy the ozone layer. More than 30 years later we can measure the benefits of this agreement in our planet’s atmosphere.

A matter of science, not politics

Unlike the current climate change debate, people largely saw this risk as a matter of science, not politics.

But it seems people are increasingly encouraged to see risks like this through a political frame. When this happens, facts can become irrelevant because no matter how smart people are, many will simply deny the evidence to protect their side of the political debate.




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Societies need to make good choices for their survival and those choices need to be based on facts, regardless of whether everyone likes them or not.


This research was conducted by Matthew Nurse as part of a master’s thesis at the Australian National Centre for the Public Awareness of Science.The Conversation

Will J Grant, Senior Lecturer, Australian National Centre for the Public Awareness of Science, Australian National University

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

There’s a looming waste crisis from Australia’s solar energy boom



Rooftop solar has boomed, but soalr panels only last about 20 years. What happens to the waste?
Flickr, CC BY-SA

Rodney Stewart, Griffith University; Hengky Salim, Griffith University, and Oz Sahin, Griffith University

As Australians seek to control rising energy costs and tackle the damaging impacts of climate change, rooftop solar has boomed.

To manage the variability of rooftop solar – broadly, the “no power at night” problem – we will also see a rapid increase in battery storage.

The question is: what will happen to these panels and batteries once they reach the end of their life?

If not addressed, ageing solar panels and batteries will create a mountain of hazardous waste for Australia over the coming decades.

Our research, published recently in the Journal of Cleaner Production, looked at the barriers to managing solar panel waste, and how to improve it.

A potentially toxic problem

Solar panels generally last about 20 years. And lead-acid and lithium-ion batteries, which will be the most common battery storage for solar, last between five and 15 years. Many solar panels have already been retired, but battery waste will start to emerge more significantly in 2025. By 2050 the projected amount of waste from retired solar panels in Australia is over 1,500 kilotonnes (kT).

Mass of end of life solar panels (a) and battery energy storage (b) 2020-2050.
Salim et al. 2019

Solar panels and batteries contain valuable materials such as metals, glass, ruthenium, indium, tellurium, lead and lithium.

Recycling this waste will prevent environmental and human health problems, and save valuable resources for future use.

Product stewardship

Australia has a Product Stewardship Act, which aims to establish a system of shared responsibility for those who make, sell and use a product to ensure that product does not end up harming the environment or people at the end of its life.

In 2016, solar photovoltaic (PV) systems were added to a priority list to be considered for a scheme design. This includes an assessment of voluntary, co-regulatory and regulatory pathways to manage the waste streams.

Sustainability Victoria (on behalf of the Victorian state government and with the support of states and territories) is leading a national investigation into a system of shared responsibility for end-of-life solar photovoltaic systems in Australia. Our research project has supported the assessment process.

Industries play a crucial role in the success of any product stewardship scheme. As we move into assessing and testing possible schemes, Australia’s PV sector (and other stakeholders) will have critical input.

A preferred product scope and stewardship approach will be presented to environment ministers. Scheme design and implementation activities are tentatively set to start in 2020.

Moving towards a circular economy

Federal and state environment ministers recently agreed to update the National Waste Policy to incorporate the principles of a circular economy.

This approach aims to reduce the need for virgin raw materials, extend product life, maintain material quality at the highest level, prioritise reuse, and use renewable energy throughout the process.




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Businesses in Australia currently have little incentive to innovate and improve the recycling rate. By helping implement circular business models such as lease, refurbishment and product-service systems, we can boost recycling, reduce collection costs and prolong tech lifetimes.

Requiring system manufacturers, importers or distributors to source solar panels and batteries designed for the environment makes both economic and environmental sense. By doing so, recyclers will recover more materials and achieve higher recirculation of recovered resources.

Consumers need to be provided with proper guidance and education for responsible end-of-life management of solar panels and batteries.

Immature domestic recycling capability

Now that China is no longer accepting waste for recycling, Australia needs to rapidly develop its domestic recycling industry. This will also spur job creation and contribute to the green economy.

Given Australia is struggling to recycle simple waste, such as cardboard and plastics, in a cost-effective way, we need to question our capability to deal with more complex solar PV and battery waste.

Australia currently has little capacity to recycle both solar panels and batteries.

And even if China were to suddenly start accepting Australia’s waste – an unlikely proposition – we cannot simply export our problem. As a signatory to the Basel Convention, exporting hazardous materials requires permits.

A previous study suggests half of Australia’s scrap metal is exported for overseas processing, which indicates the lack of incentives for domestic recycling.

Even if we build domestic recycling capability for solar panels and batteries, it will be underused while landfills remain available as a low-cost disposal option.

It’s promising that South Australia and the ACT have banned certain e-waste categories from entering landfill, while Victoria will implement an all-encompassing e-waste landfill ban from July 1 2019. This means any end-of-life electrical or electronic device that requires an electromagnetic current to operate must be recycled.

Creating a circular economy for solar and battery waste will need a strong commitment from policymakers and industry. Ideally, we need to prioritise reuse and refurbishment before recycling.

If we combine sensible policies with proactive business strategy and education to promote recycling rates, we can have a reliable and truly sustainable source of renewable energy in this country.


The authors would like to acknowledge the contribution of Michael Dudley from Sustainability Victoria to this article.The Conversation

Rodney Stewart, Professor, Griffith School of Engineering, Griffith University; Hengky Salim, PhD Candidate, Griffith University, and Oz Sahin, Senior Research Fellow, Griffith University

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

How to answer the argument that Australia’s emissions are too small to make a difference


Matt McDonald, The University of Queensland

After a recent foray into the debate over Australia’s so-called “climate election”, I received plenty of critical replies to my argument that Australians should take climate action more seriously. The most common rebuttal was that Australians were right to focus on other issues at the ballot box because Australia’s contribution to global climate change is small anyway.

This is precisely the argument Alan Jones advanced in a now notorious Sky News segment in which he used a bowl of rice to explain away Australia’s climate obligations.

Australia, Jones noted, contributes only 1.3% of global carbon dioxide emissions from human activity, which in turn represents just 3% of the overall amount of CO₂ in the atmosphere, which in turn makes up little more than 0.04% of the whole atmosphere. So why, he asked while triumphantly brandishing a single rice grain, are we so obsessed with Australia’s climate policy when the planet is so big and the consequences of our actions are so tiny?




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This is a powerful critique and, on the face of it, a simple and compelling line of argument, which is precisely why it’s so often used. Why bother, if we lack the power to do anything that makes a difference?

But there are at least three obvious responses to it.

The ‘per capita’ problem

The first and most obvious response is that Australia emits much more than our fair share.

Sure, our emissions are 1.3% of the global total. But our population is 0.3% of the global total.

This isn’t the only way to allocate national emissions targets. But if rich countries like Australia aren’t doing more to reduce their disproportionately high emissions, what possible incentive is there for developing countries to take the issue seriously? Nations such as India, Brazil and China can ask – as indeed they have at various climate talks – why they should reduce emissions when Australia does so little.

In this sense, Australia’s position on climate action is significant, not only for the 1.3% of greenhouse gases we produce, but for the potential influence on global policy.

As a nation so proud of “punching above its weight” in fields such as sport and technology, Australia is missing a big chance to show global leadership on climate.

The ‘coal exports’ problem

The 1.3% statistic is only true if we focus purely on greenhouse emissions within Australia itself. Fair enough, you might say, given that this is the way the Paris Agreement, and the Kyoto Protocol before it, measures countries’ emissions.

But this approach excludes some significant factors.

First, it fails to take proper account of emissions created in one country while manufacturing goods for export to other countries. Emissions due to Chinese-produced goods destined for Australian consumers, for example, count towards China’s emissions, not Australia’s. If we take this “consumption shadow” into account, the climate impact of developed countries, including Australia, becomes much higher.

Second, there is a similar issue with coal exports. Coal dug up by one country but burned in another counts towards the latter’s emissions. As one of the world’s largest coal exporters, this is clearly important for Australia.

In 2012, the campaign group Beyond Zero Emissions estimated that if Australian coal was factored into Australia’s emissions, our contribution to global emissions would be 4% rather than 1.3%. This would make Australia the world’s sixth-largest contributor to climate change.

Are we responsible for what other countries do with Australian coal? According to the Paris treaty, the answer is no. But drug barons and arms dealers use similar arguments to wash their hands of drug addiction and war.

What’s more, Australia already limits a range of exports based on concerns about their use in importing countries, including weapons, uranium and even livestock.

So there’s certainly a precedent for viewing exports through the lens of our international responsibilities. And with the UN secretary-general joining recent calls to end all new coal power plants, a global coal treaty or even embargo might eventually force Australia’s hand.

The ‘capacity to respond’ problem

The third rebuttal to Alan Jones’s arguments is that Australia has far more capacity to take climate action than many other nations. Again, this works at two levels.

First, we’re rich. Australia is a top-20 world economy in terms of both size and average wealth. This means we are more able than most countries to manage the economic costs of moving away from fossil fuels.

Second, thanks to decades of relative climate policy inaction and modest targets, there’s a lot of low-hanging fruit for Australia to ratchet up its climate ambition. This applies most obviously to the renewable energy sector, but also to areas such as energy efficiency and transport.

Australia’s land-clearing rates are also among the highest in the world – we are the only developed nation to feature in a 2018 WWF list of deforestation hotspots. Reducing this would significantly cut emissions while also protecting important carbon stores.

As economist John Quiggin has noted, the longer we wait to move away from fossil fuels, the more expensive it will be.

What does this all mean for Australia?

Jones’s argument is a beguilingly simplistic response to a wicked problem. Climate change is a global problem that requires global action. But the calculations around who should take the lead, and how much constitutes each nation’s fair share, are fiendishly complex.

But, by almost any measure, a country like Australia should be leading the way on climate policy, not being dragged kicking and screaming to take action that falls far behind that of comparable nations.




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The current reluctance to act seriously on climate change appears at best self-serving and at worst an outright moral failing.

We should take the argument that Australia’s climate contribution is insignificant with a grain of salt. Or perhaps rice.The Conversation

Matt McDonald, Associate Professor of International Relations, The University of Queensland

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

Undocumented plant extinctions are a big problem in Australia – here’s why they go unnoticed



Matchstick banksia (Banksia cuneate). There are only about 500 of these plants left in the wild at 11 different sites, with much of its habitat having been historically cleared for agriculture.
Andrew Crawford/Threatened Species Hub

David Coates, University of Western Australia

A recent survey on the world’s plants found a shocking number have gone extinct – 571 since 1750. And this is likely to be a stark underestimate. Not all plants have been discovered, so it’s likely other plants have gone extinct before researchers know they’re at risk, or even know they exist.

In Australia, the situation is just as dire. The Threatened Species Recovery Hub recently conducted two evaluations that aren’t yet published of extinct plants in Australia. They found 38 have been lost over the last 170 years, such as the Daintree River banana (Musa fitzalanii) and the fringed spider-orchid (Caladenia thysanochila).




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But uncertainty about the number of plant extinctions, in addition to the 38 confirmed, is an ongoing concern.

Both studies pointed out the actual number of extinctions is likely to be far more than those recognised in formal lists produced by the Commonwealth and state and territory agencies.

For example, there is still a high rate of discovery of new plant species in Australia. More than 1,600 plants were discovered between 2009 and 2015, and an estimated 10% are still yet to be discovered.

The extinction of Australian plants is considered most likely to have occurred in areas where there has been major loss and degradation of native bushland. This includes significant areas in southern Australia that have been cleared for agriculture and intensive urbanisation around major cities.

Many of these extinct plants would have had very restricted geographic ranges. And botanical collections were limited across many parts of Australia before broad scale land clearing and habitat change.

Why extinction goes undocumented

There is already one well recognised Australian plant extinction, a shrub in Phillip Island (Streblorrhiza speciosa), which was never formally recognised on any Australian threatened species list.

Black magic grevillea (Grevilla calliantha) is known from only six populations within a range of 8 square kilometres. In the wild the species is threatened by frequent fire, habitat loss, invasive weeds, herbicide overspray, grazing animals and phytophthora dieback.
Dave Coates

Researchers also note there are Australian plants that are not listed as extinct, but have not been collected for 50 years or more.

While undocumented extinction is an increasing concern, the recent re-assessment of current lists of extinct plants has provided a more positive outcome.

The re-assessment found a number of plants previously considered to be extinct are not actually extinct. This includes plants that have been re-discovered since 1980, and where there has been confusion over plant names. Diel’s wattle (Acacia prismifolia), for instance, was recently rediscovered in Western Australia.




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A significant challenge for accurately assessing plant extinction relates to the difficulties in surveying and detecting them in the Australian landscapes.

Many have histories associated with fire or some other disturbance. For example, a number of plants spend a significant part of their time as long-lived seeds – sometimes for decades – in the soil with nothing visible above ground, and with plants only appearing for a few years after a fire.

But by far, the greatest reason for the lack of information is the shortage of field surveys of the rare plants, and the availability of botanists and qualified biologists to survey suitable habitat and accurately identify the plants.

Purple-wood wattle (Acacia carneorum) is slow growing and rarely produces viable seed. Threats are not well understood but grazing by livestock and rabbits is likely to impact on the species.
Andrew Denham

What we’ve learnt

The continuing decline of Australia’s threatened plants suggests more extinctions are likely. But there have been important achievements and lessons learnt in dealing with the main causes of loss of native vegetation.

Our understanding of plant extinction processes – such as habitat loss, habitat degradation, invasive weeds, urbanisation, disease and climate change – is improving. But there is still a significant way to go.




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One challenge in dealing with the causes of Australian plant extinction is how to manage introduced diseases.

Two plant diseases in particular are of major concern: Phytophthora dieback, a soil-borne water mould pathogen, and Myrtle rust, which is spread naturally by wind and water.

Both diseases are increasingly recognised as threats, not only because of the impact they are already having on diverse native plant communities and many rare species, but also because of the difficulties in effective control.

Two Australian rainforest tree species Rhodomyrtus psidioides and Rhodamnia rubescens were recently listed as threatened under the NSW legislation because of myrtle rust.

Native guava (Rhodomyrtus psidioides) A tree species around the margins of rainforest between the NSW and the QLD border. The species is has now been listed as Critically Endangered. Surveys of rainforest areas infected with Myrtle Rust found that 50 to 95% of native guava trees were killed by the disease within a few years.
Zaareo/Wikimedia

While extinction associated with disease is often rapid, some individual plants may survive for decades in highly degraded landscapes, such as long-lived woody shrubs and trees. These plants will ultimately go extinct, and this is often difficult to communicate to the public.

While individual species will continue to persist for many years in highly disturbed and fragmented landscapes, there is little or no reproduction. And with their populations restricted to extremely small patches of bush, they’re vulnerable to ongoing degradation.




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In many such cases there is an “extinction debt”, where it may take decades for extinction to occur, depending on the longevity of the plants involved.

But it’s not all doom and gloom. A recent study found of the 418 threatened Australian plants showing ongoing decline, 83% were assessed as having medium to high potential for bouncing back.

And with long-term investment and research there are good prospects of saving the majority of these plants.The Conversation

David Coates, Adjunct Professor and Research Associate, University of Western Australia

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

Built like buildings, boab trees are life-savers with a chequered past



A boab tree in the Kimberley. Boab trees can live for thousands of years and their trunks hollow out as they get older.
Shutterstock

Gregory Moore, University of Melbourne

Sign up to the Beating Around the Bush newsletter here, and suggest a plant we should cover at batb@theconversation.edu.au.


When you are in the northern part of Western Australia, one of nature’s joys is seeing a large boab tree close up, perhaps for the first time.

The boab (Adansonia gregorii) is a native to this part of Australia, but is related to the broader group of species called boababs that live in Madagascar and Africa – but more on that connection later.

Boabs are also called bottle trees, the tree of life, boababs and Australian boababs. Some of the indigenous Australian names include gadawon and larrgadi.

From their iconic swollen trunks, to living up to 2,000 years and the many uses for their “superfood” fruits, here’s what makes boab trees so fascinating.



The Conversation

The ‘upside-down tree’: trunks that save lives and lock up prisoners

While the boab in Australia is not quite as well-documented as the African species, specimens have been recorded at over 1,000 years of age. Some living trees have been estimated to be nearer to 2,000 years old.

And while it’s difficult to age the trees, several specimens of the African species have been dated at 2,000 or more years old.

Australian boabs can grow up to 15 metres tall at maturity and have swollen, attention-grabbing trunks called a caudex, which may be up to five metres in diameter.

The African boab species, A. digitata, can be much taller, at 25 metres high and with a diameter of up to 15 metres.




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Iconic boab trees trace journeys of ancient Aboriginal people


In such dry continents, the caudex is a life-saver, often containing water, which was tapped by Indigenous folk. It has been estimated that some of these huge old trees can hold more than 100,000 litres of water in their trunks.

In Africa, these massive trunks have been used as shelters, homes, farm sheds and, more recently, even shops and bars.

Sadly in Australia, legend has it the huge trunks were used to make lock-ups for Indigenous people and other prisoners.

The infamous Boab Prison Tree, just south of Derby in Western Australia, was said to have once held Indigenous prisoners.
Shutterstock

It’s not just the trunk that can stop you in your tracks. The boab has a unique branching structure, one that looks more like a root system than a canopy.

Some locals in Africa will tell you the tree was dropped from heaven to earth and landed upside down. So the African species of boab is sometimes called the upside-down tree.

Boab fruits are ‘superfoods’ and its shell has many uses

A. gregorii, the Australian boab species, has large, attractive white flowers up to 75 millimetres in length. Its round fruits are edible and sought after by birds, mammals and humans. The fruit gives rise to some of the common names for the tree, such as monkey bread tree and dead rat tree. The latter comes from the appearance of older fruits in the canopy looking a bit like … well, dead rats?




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Baobab trees have more than 300 uses but they’re dying in Africa


In fact, there’s great interest in fruits from the African species, A. digitata, which are considered a “superfood” because of their high levels of antioxidants, calcium, potassium, magnesium, fibre and vitamin C. It’s assumed many of these traits will be shared by the Australian boab, but there is little research as yet to prove it.

Fruit of the African boab tree fruit are initially covered in velvety fur.
Ton Rulkens/Wikimedia, CC BY-SA

The soft part of the fruit is surrounded by a hard, coconut-like shell that’s initially covered in a velvety fur. The hard shell has been used for cups and bowls, but has also been intricately carved and decorated by Aboriginal artists in Africa and Australia. If the seeds are left inside the fruit as it dries, they can be used for toys like rattles.

On both continents, Aboriginal people have eaten the white powder that surrounds the seeds. The leaves are rich in iron and the pulp from the fruits tastes like cream of tartar.

The Indigenous people of both continents were also well aware of the medicinal uses of the fruits. The bark and leaves of the trees also treat various ailments, but particularly those associated with digestive disorders.




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But at present there is very little modern research on the medicinal and dietary aspects of either the baobab or boab.

How the boab tree got to Australia

One of the mysteries surrounding the boab is how it got to Australia – the Australian species has clear affinities with related species in continental Africa and Madagascar.

A baobab tree, Adansonia digitata, in Tarangire National Park, Tanzania. Its journey from Africa to Australia remains a mystery.
Yoki/Wikimedia, CC BY-SA

There are three intriguing theories.

The first is that all of the boababs originate from the super-continent Gondwana – consisting of Africa, South America, Antarctica, Australia, India and Madagascar – before it fragmented almost 80 million years ago. But A. Gregorii and A. digitata are so similar genetically that, given the millions of years that have elapsed, this theory is now in question.

The second theory comes from recent DNA analysis of the species. It suggests they separated more recently, perhaps only 70,000 years ago, which raises the question, were humans involved in their journey? But did they come to Australia from Africa, or from Australia to Africa? The latter is a less likely scenario given the direction of ocean currents.

And the third theory is that fruits arrived on the Australian shore after an epic ocean voyage from Africa.




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Boabs are usually found in the remote outback of Australia, but in 2008, a large 750-year-old boab was transported from Warmun in the Kimberley to Perth and transplanted in Kings Park.

Transplanting such a large tree is both daunting and fraught, with a high chance of failure, but the deciduousness and growth habit of the boab gave some cause for optimism about a successful outcome. For the reward of having a large old boab growing in Perth, it would be worth it.

After a period of stress, the tree appears to be coming good, reflecting the toughness of the species.

A large, mature boab is a splendid tree of arid Australia that inspires awe in all who experience them close up. They really are a beauty and a bottler of a tree!


Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.The Conversation

Gregory Moore, Doctor of Botany, University of Melbourne

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

5 ways the government can clean up the Murray-Darling Basin Plan


Barry Hart, Monash University and Martin Thoms, University of New England

The health of the Murray-Darling Basin, Australia’s largest and most complex river system, is in rapid decline, and faces major challenges over the next 30 years as the climate changes.

In our view, there are still major problems with the implementation of the Murray-Darling Basin Plan. These must be addressed to make sure the system is resilient enough to have a reasonable chance of bouncing back from future shocks to the river’s ecosystems, particularly due to climate change.




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Here are five ways the government can clean up the Murray-Darling Basin Plan so the river system has a chance of surviving in the long term.

1. Allow the rivers to spill into the floodplain

There are restrictions in all states on deliberately using environmental water (water set aside to keep the rivers healthy) to go over the river bank and inundate the floodplain. When this happens, it’s known as “overbank flow”, and is restricted to areas and times of year when it’s permitted.

Overbank flow is the connection between rivers and their floodplain, and is essential for two reasons.

Populations of water birds like pelicans are not recovering as well as they used to after drought and flood cycles in the Basin.
Shutterstock

The first is to ensure floodplain wetlands and forests are resilient. For example, without additional water, the current red gum forests along the River Murray are likely to die and be replaced with black box trees, which need less water.

The second is for the exchange of nutrients and organic matter between rivers and floodplains. Without these inputs from the floodplain, the river system would only be able to support a much smaller number of fish.

Governments have been reluctant to work towards increased overbank flows, largely because of a potential backlash from landholders who don’t want their floodplain land to be flooded.




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But in several regions, such as the Edward-Wakool system in New South Wales, landowners and government officials are working through the issues that infrequent flooding has on riverside agricultural land, such as stock being unable to graze flooded areas, crops being innundated by floodwaters, and loss of access to parts of their property through road flooding.

We hope their discussions will lead to a balance, where overbank flows can still occur with minimum impact on landholders.

Still, without changes to state policies on overbank flows, parts of the Basin’s floodplain systems are unlikely to have sufficient resilience to absorb future stresses.

2. Better management of the rivers

The Commonwealth and states now have almost 3 trillion litres (3,000 gigalitres) of dedicated environmental water, purchased from irrigators, many of whom have made significant water savings by upgrading their irrigation equipment.

This is called “held” environmental water. Currently, there is around 3 trillion litres of held environmental water, and 13.7 trillion litres of water allocated to irrigators in the Murray-Darling Basin.

Management of this environmental water is relatively new, compared with the management of water for irrigators, which has been occurring for the better part of 80 years in rivers such as the Murray, Goulburn and Murrumbidgee.

There is a major difference in when environmental and irrigation water is needed through the year. Farmers have their highest water demand for irrigation in late spring and summer, while the major environmental water demand is often highest in late winter and early spring. This is when high natural inflows would have filled river channels and spilled into floodplain forests and wetlands.

The use of the river channels to deliver irrigation water has lead to large flows in the summer when naturally the river flows would have been low. This has resulted in environmental problems, such as bank erosion and the wrong triggers for fish breeding.

3. A greater focus on river refuges

During periods of low or no flow, many of the Basin’s rivers exist as networks of waterholes. In such dry periods, these waterholes are vital habitats, or “refuges”, for fish, frogs, waterbugs, and other species that need permanent water.

Changes in land use, flow regimes and the condition of riverbank vegetation all threaten the ability for these waterholes to act as refuges for these species. These waterhole refuges also need a full set of structural habitats, such as snags and riverbank vegetation.




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Maintaining a “mosaic” of refuges with different levels of connection is required for the full suite of species to be able to survive droughts.

4. Better protection of planned environmental water

Runoff – rainwater that drains from the land and into the rivers – will be seriously affected by climate change.

A predicted 20% reduction in rainfall is expected in the southern Basin by 2050. This would translate to a 40-50% reduction in runoff, and would impact on all water in the Murray-Darling Basin.

Disturbingly, the current policy in the Basin Plan safeguards the entitlements to irrigation water and held environmental water, but not the rest of the flow – which is largely also “environmental” water. Currently, this makes up around half of the total flow (32.5 trillion litres per year) in the Murray-Darling Basin a very large volume.

Drought stricken wetlands of the Murray-Darling Basin. We need a more coordinated management of all of the Basin’s natural resources.
Shutterstock

The effect varies over the basin, but by 2030, overall losses are predicted to be two to three times greater for water that is outside of these entitlements, compared with irrigation water and held environmental water.

Unless this policy is changed, climate change will have an excessive impact on the river’s health. Entitlement-holders will continue to take the same amount of water while the overall river flow drops dramatically. This deficiency must be addressed when the Basin Plan is reviewed by 2026.

5. Linking water and other natural resource management

The Basin’s water resources do not exist in isolation from other “natural capital”, such as riverbank habitats, floodplain land, and the surrounding catchments.

Before the Basin Plan, the Murray-Darling Basin Commission had in place an integrated natural resource management strategy, but this has now been discontinued.

River scientists know “the catchment rules the river”. But the water and catchments are now managed separately, despite many calls over the years for better integration.

Poor agricultural practices result in sediment, nutrients and salt entering the rivers in runoff. This reduces water quality and harms the Basin’s ability to provide essential “ecosystem services”, such as water quality improvement and the effective functioning of the ecosystem.




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We believe a more coordinated management of all natural resources in the Basin, and attention to other complementary measures, should be addressed when the current Basin Plan is reviewed in 2026.

We submit that continuing with the existing Basin Plan, it’s unlikely the Murray-Darling Basin will be resilient enough to withstand future climate impacts, and we will see major detrimental changes to the basin’s ecosystems.

At the very least, we must properly implement the current Basin Plan by addressing the first three issues above, and also make the necessary policy change to ensure the other two issues – protection of planned environmental water and better links with other natural resources – are addressed in the next Basin Plan in 2026.The Conversation

Barry Hart, Emeritus Professor Water Science, Monash University and Martin Thoms, Professor – Faculty of Humanities, Arts, Social Sciences and Education; School of Humanities, Arts, and Social Sciences , University of New England

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