Even after the rains, Australia’s environment scores a 3 out of 10. These regions are struggling the most


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Albert Van Dijk, Australian National University; Marta Yebra, Australian National University, and Shoshana Rapley, Australian National UniversityImproved weather conditions have pulled Australia’s environment out of its worst state on record, but recovery remains partial and precarious, new research reveals.

Each year, we collate a vast number of measurements on the state of our environment. The data are collected in many different ways – including satellites, field stations and surveys – then combined to produce an overall national score.

A year ago, after prolonged drought and devastating bushfires, Australia’s environment scored a shocking 0.8 out of ten. Our new research shows nature started its long road to recovery in 2020, especially in New South Wales and Victoria. Some of the regions with the poorest scores have high levels of social disadvantage, which risks being further entrenched by environmental disasters such as drought, bushfire and heatwaves.

Nationally, Australia’s environmental condition score increased by 2.6 points last year, to reach a (still very low) score of 3.2. But overall conditions across large swathes of the country remain poor.

Environmental Condition Score for 2020 by state and territory.
ANU Fenner School

Scores rising but still in the red

From a long list of environmental indicators we report on, seven are selected to calculate an overall score for each region, as well as nationally.

These indicators – high temperatures, river flows, wetlands, soil health, vegetation condition, growth conditions and tree cover – are chosen because they allow a comparison against previous years. See the graphic below to find the score for your region.

The largest improvements occurred in NSW and Victoria thanks to good rains. The poorest conditions occurred in the Northern Territory and Western Australia, where there was little solace from dry conditions.

Comparing local government areas, the best conditions occurred in Nillubik Shire on the northern edge of Melbourne. In contrast, the worst conditions occurred in Katherine in the Northern Territory and in the Shire of Ngaanyatjarraku in remote WA.



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From drought to rain

2020 started as badly as 2019 ended – with extreme temperatures, drought and fires, especially in Australia’s southeast. The Sydney suburb of Penrith was the hottest place on Earth on January 4 and, following the bushfires, Canberra had the most dangerous air quality in the world for several days. Clearly, climate change is already affecting our cities and nature.

By the end of summer, the high temperatures also caused another mass coral bleaching in the Great Barrier Reef – the third such event in five years.

Only in February-March did the weather turn, providing good and in some areas very plentiful rains – for example along the NSW coast. Later in the year officials declared an La Niña event – an ocean circulation pattern that normally encourages rainfall in Australia.

While rainfall was not extraordinarily high, it lifted most regions in eastern Australia out of extreme drought. Some parts of northern and western Australia missed out, however, and in some areas the drought deepened.

Taken as an average over the year and over the country, rainfall was 10% above the average for the previous two decades. The number of hot days – those reaching 35℃ – was 11% or nine days more than the 20-year average.

Values for 15 environmental indicators in 2020, expressed as the change from average 2000-2019 conditions. Similar to national economic indicators, they provide a summary but also hide regional variations, complex interactions and long-term context.
ANU Fenner School

The improved rainfall helped replenish dried soils, and national average soil moisture was close to average. Growth conditions for the NSW wheatbelt were the best in many years and tree cover increased in northern and eastern Australia.

The rain refilled many dams and reservoirs, especially in Canberra and Sydney. It also made some eastern rivers flow again, including the Darling River in NSW. But with such dry starting conditions, wetlands in inland eastern Australia filled only modestly and waterbird numbers remained low.

Drought persisted across large swathes of inland northern and western Australia, where in some parts, vegetation growth conditions were the worst in decades. And the surplus rain was often not enough to reach wetlands, which continued to shrink.




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New shoots in forest after fire
Signs of life: some parts of Australia have benefited from recent rain.
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Bushfires: few but locally severe

Fire activity in vast areas of inland Australia was very low, because a run of dry years did not leave much dry grass to burn.

Nationally, the total area burnt was 17 million hectares – 90% below the 20-year average. This led to 80 million tonnes of carbon emissions (43% below average).

Fire activity was not low everywhere. In southeast Australia, fires in southern NSW, East Gippsland and the ACT severely damaged forests and other ecosystems as well as people and property.

The full ecological damage of the Black Summer fires was not entirely apparent in 2020. That’s partly because COVID-19 restrictions made the situation difficult to assess.

The fires burned more than 80% of the habitat of 30 threatened species, and may have been the death blow for several. Food shortages and feral cats further reduced populations of surviving animals in the burnt ecosystems.

But some wildlife proved unexpectedly resilient. For example, a great effort by citizen scientists showed frogs rebounded well after the rains.

Another 15 species were added to the Threatened Species List in 2020. In good news, three species were removed from the list, including two species of tree frogs that recovered from the global chytrid fungus.




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Stopping the slow train wreck

The accelerating impacts of climate change will not stop here. New records will inevitably be broken. Heat, drought and fire will again damage our environment and lives. Some ecosystems will be lost forever. But even worse outcomes can be avoided – if the world can rein in greenhouse gas pollution.

There’s cause for cautious optimism. International pressure may force the Morrison government’s hand on climate action. Several states and territories have already taken decisive climate action. Low-emission energy and transport are advancing quickly. As individuals we can fly and drive less, get solar panels and divest from fossil fuel companies.

In the meantime, we must adapt to inevitable climate change and reduce other pressures on our ecosystems. Citizen scientists have proven essential in monitoring how individual species are faring – so download that app and enjoy nature even more. And plant a few trees to help nature along.

Finally, pressure your local, state and national politicians. Ask them: how are you addressing vegetation loss, invasive pests and over-extraction from rivers? If you don’t like the answer, tell them, or try to vote them out.

With greater urgency and some luck, there is still much to be salvaged.

The full report and a video summary are available here.




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This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. You can read the rest of the stories here.The Conversation

Albert Van Dijk, Professor, Water and Landscape Dynamics, Fenner School of Environment & Society, Australian National University; Marta Yebra, Associate Professor in Environment and Engineering, Australian National University, and Shoshana Rapley, Research assistant, Australian National University

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

A brutal war and rivers poisoned with every rainfall: how one mine destroyed an island



Locals living downstream of the abandoned mine pan for gold in mine waste.
Matthew Allen, Author provided

Matthew G. Allen, The University of the South Pacific

This week, 156 people from the Autonomous Region of Bougainville, in Papua New Guinea, petitioned the Australian government to investigate Rio Tinto over a copper mine that devastated their homeland.

In 1988, disputes around the notorious Panguna mine sparked a lengthy civil war in Bougainville, leading to the deaths of up to 20,000 people. The war is long over and the mine has been closed for 30 years, but its brutal legacy continues.




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When I conducted research in Bougainville in 2015, I estimated the deposit of the mine’s waste rock (tailings) downstream from the mine to be at least a kilometre wide at its greatest point. Local residents informed me it was tens of metres deep in places.

I spent several nights in a large two-story house built entirely from a single tree dragged out of the tailings — dragged upright, with a tractor. Every new rainfall brought more tailings downstream and changed the course of the waterways, making life especially challenging for the hundreds of people who eke out a precarious existence panning the tailings for remnants of gold.

The petition has brought the plight of these communities back into the media, but calls for Rio Tinto to clean up its mess have been made for decades. Let’s examine what led to the ongoing crisis.

Triggering a civil war

The Panguna mine was developed in the 1960s, when PNG was still an Australian colony, and operated between 1972 and 1989. It was, at the time, one of the world’s largest copper and gold mines.

It was operated by Bougainville Copper Limited, a subsidiary of what is now Rio Tinto, until 2016 when Rio handed its shares to the governments of Bougainville and PNG.

When a large-scale mining project reaches the end of its commercial life, a comprehensive mine closure and rehabilitation plan is usually put in place.




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But Bougainville Copper simply abandoned the site in the face of a landowner rebellion. This was largely triggered by the mine’s environmental and social impacts, including disputes over the sharing of its economic benefits and the impacts of those benefits on predominantly cashless societies.

Following PNG security forces’ heavy-handed intervention — allegedly under strong political pressure from Bougainville Copper — the rebellion quickly escalated into a full-blown separatist conflict that eventually engulfed all parts of the province.

By the time the hostilities ended in 1997, thousands of Bougainvilleans had lost their lives, including from an air and sea blockade the PNG military had imposed, which prevented essential medical supplies reaching the island.

The mine’s gigantic footprint

The Panguna mine’s footprint was gigantic, stretching across the full breadth of the central part of the island.

The disposal of hundreds of millions of tonnes of tailings into the Kawerong-Jaba river system created enormous problems.

Rivers and streams became filled with silt and significantly widened. Water flows were blocked in many places, creating large areas of swampland and disrupting the livelihoods of hundreds of people in communities downstream of the mine. These communities used the rivers for drinking water and the adjacent lands for subsistence food gardening.

Several villages had to be relocated to make way for the mining operations, with around 200 households resettled between 1969 and 1989.

In the absence of any sort of mine closure or “mothballing” arrangements, the environmental and socio-economic impacts of the Panguna mine have only been compounded.

Since the end of mining activities 30 years ago, tailings have continued to move down the rivers and the waterways have never been treated for suspected chemical contamination.




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Long-suffering communities

The 156 complainants live in communities around and downstream of the mine. Many are from the long-suffering village of Dapera.

In 1975, the people of Dapera were relocated to make way for mining activities. Today, it’s in the immediate vicinity of the abandoned mine pit. As one woman from Dapera told me in 2015:

I have travelled all over Bougainville, and I can say that they [in Dapera] are the poorest of the poor.

They, and others, sent the complaint to the Australian OECD National Contact Point after lodging it with Melbourne’s Human Rights Law Centre.

The complainants say by not ensuring its operations didn’t infringe on the local people’s human rights, Rio Tinto breached OECD guidelines for multinational enterprises.

The Conversation contacted Rio Tinto for comment. A spokesperson said:

We believe the 2016 arrangement provided a platform for the Autonomous Bougainville Government (ABG) and PNG to work together on future options for the resource with all stakeholders.

While it is our belief that from 1990 to 2016 no Rio Tinto personnel had access to the mine site due to on-going security concerns, we are aware of the deterioration of mining infrastructure at the site and surrounding areas, and claims of resulting adverse environmental and social, including human rights, impacts.

We are ready to enter into discussions with the communities that have filed the complaint, along with other relevant parties such as BCL and the governments of ABG and PNG.

A long time coming

This week’s petition comes after a long succession of calls for Rio Tinto to be held to account for the Panguna mine’s legacies and the resulting conflict.

A recent example is when, after Rio Tinto divested from Bougainville Copper in 2016, former Bougainville President John Momis said Rio must take full responsibility for an environmental clean-up.

And in an unsuccessful class action, launched by Bougainvilleans in the United States in 2000, Rio was accused of collaborating with the PNG state to commit human rights abuses during the conflict and was also sued for environmental damages. The case ultimately foundered on jurisdictional grounds.

Two people, one waist-deep in tailings.
Hundreds of millions of tonnes of tailings were deposited in the rivers.
Matthew Allen, Author provided

Taking social responsibility

This highlights the enormous challenges in seeking redress from mining companies for their operations in foreign jurisdictions, and, in this case, for “historical” impacts.

The colonial-era approach to mining when Panguna was developed in the 1960s stands in stark contrast to the corporate social responsibility paradigm supposedly governing the global mining industry today.




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Indeed, Panguna — along with the socially and environmentally disastrous Ok Tedi mine in the western highlands of PNG — are widely credited with forcing the industry to reassess its “social license to operate”.

It’s clear the time has come for Rio to finally take responsibility for cleaning up the mess on Bougainville.The Conversation

Matthew G. Allen, Professor of Development Studies, The University of the South Pacific

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

How bushfires and rain turned our waterways into ‘cake mix’, and what we can do about it



The Murray River at Gadds Reserve in north east Victoria after Black Summer bushfires.
Paul McInerney, Author provided

Paul McInerney, CSIRO; Anu Kumar, CSIRO; Gavin Rees, CSIRO; Klaus Joehnk, CSIRO, and Tapas Kumar Biswas, CSIRO

As the world watched the Black Summer bushfires in horror, we warned that when it did finally rain, our aquatic ecosystems would be devastated.

Following bushfires, rainfall can wash huge volumes of ash and debris from burnt vegetation and exposed soil into rivers. Fires can also lead to soil “hydrophobia”, where soil refuses to absorb water, which can generate more runoff at higher intensity. Ash and contaminants from the fire, including toxic metals, carbon and fire retardants, can also threaten biodiversity in streams.




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As expected, when heavy rains eventually extinguished many fires, it turned high quality water in our rivers to sludge with the consistency of cake mix.

In the weeks following the first rains, we sampled from these rivers. This is what we saw.

Sampling the upper Murray River

Of particular concern was the upper Murray River on the border between Victoria and NSW, which is critical for water supply. There, the bushfires were particularly intense.

Sludge in Horse Creek near Jingellic following storm activity after the fire.
Paul McInerney/Author Provided

When long-awaited rain eventually came to the upper Murray River catchment, it was in the form of large localised storms. Tonnes of ash, sediment and debris were washed into creeks and the Murray River. Steep terrain within burnt regions of the upper Murray catchment generated a large volume of fast flowing runoff that carried with it sediment and pollutants.

We collected water samples in the upper Murray River in January and February 2020 to assess impacts to riverine plants and animals.

Our water samples were up to 30 times more turbid (cloudy) than normal, with total suspended solids as high as 765 milligrams per litre. Heavy metals such as zinc, arsenic, chromium, nickel, copper and lead were recorded in concentrations well above guideline values for healthy waterways.

Ash and sediment blanketing cobbles in the Murray River.
Paul McInerney/Author Provided

We took the water collected from the Murray River to the laboratory, where we conducted a number of toxicological experiments on duckweed (a floating water plant), water fleas (small aquatic invertebrates) and juvenile freshwater snails.

What we found

During a seven-day exposure to the bushfire affected river water, the growth rate of duckweed was reduced by 30-60%.

The water fleas ingested large amounts of suspended sediments when they were exposed to the affected water for 48 hours. Following the exposure, water flea reproduction was significantly impaired.

And freshwater snail egg sacs were smothered. The ash resulted in complete deaths of snail larvae after 14 days.




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These sad impacts to growth, reproduction and death rates were primarily a result of the combined effects of the ash and contaminants, according to our preliminary investigations.

But they can have longer-term knock-on effects to larger animals like birds and fish that rely on biota like snail eggs, water fleas and duckweed for food.

What happened to the fish?

Immediately following the first pulse of sediment, dead fish (mostly introduced European carp and native Murray Cod) were observed on the bank of River Murray at Burrowye Reserve, Victoria. But what, exactly, was their cause of death?

A dead Murray Cod found on the banks of the Murray River following storms after the bushfires.
Paul McInerney/Author Provided

Our first assumption was that they died from a lack of oxygen in the water. This is because ash and nutrients combined with high summer water temperatures can trigger increased activity of microbes, such as bacteria.

This, in turn can deplete the dissolved oxygen concentration in the water (also known as hypoxia) as the microbes consume oxygen. And wide-spread hypoxia can lead to large scale fish kills.




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But to our surprise, although dissolved oxygen in the Murray River was lower than usual, we did not record it at levels low enough for hypoxia. Instead, we saw the dead fish had large quantities of sediment trapped in their gills. The fish deaths were also quite localised.

In this case, we think fish death was simply caused by the extremely high sediment and ash load in the river that physically clogged their gills, not a lack of dissolved oxygen in the water.

These findings are not unusual, and following the 2003 bushfires in Victoria fish kills were attributed to a combination of low dissolved oxygen and high turbidity.

So how can we prepare for future bushfires?

Preventing sediment being washed into rivers following fires is difficult. Installing sediment barriers and other erosion control measures can protect specific areas. However, at the catchment scale, a more holistic approach is required.




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One way is to increase efforts to re-vegetate stream banks (called riparian zones) to help buffer the runoff. A step further is to consider re-vegetating these zones with native plants that don’t burn easily, such as Blackwood (Acacia melanoxylin).

Streams known to host rare or endangered aquatic species should form the focus of any fire preparation activities. Some species exist only in highly localised areas, such as the endangered native barred galaxias (Galaxias fuscus) in central Victoria. This means an extreme fire event there can lead to the extinction of the whole species.

Ash and dead fish on the banks of the Murray River near Jingellic following Black Summer fires.
Paul McInerney/Author Provided

That’s why reintroducing endangered species to their former ranges in multiple catchments to broaden their distribution is important.

Increasing the connectivity within our streams would also allow animals like fish to evade poor water quality — dams and weirs can prevent this. The removal of such barriers, or installing “fish-ways” may be important to protecting fish populations from bushfire impacts.

However, dams can also be used to benefit animal and plant life (biota). When sediment is washed into large rivers, as we saw in the Murray River after the Black Summer fires, the release of good quality water from dams can be used to dilute poor quality water washed in from fire affected tributaries.




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Citizen scientists can help, too. It can be difficult for researchers to monitor aquatic ecosystems during and immediately following bushfires and unmanned monitoring stations are often damaged or destroyed.

CSIRO is working closely with state authorities and the public to improve citizen science apps such as EyeOnWater to collect water quality data. With more eyes in more areas, these data can improve our understanding of aquatic ecosystem responses to fire and to inform strategic planning for future fires.

These are some simple first steps that can be taken now.

Recent investment in bushfire research has largely centred on how the previous fires have influenced species’ distribution and health. But if we want to avoid wildlife catastrophes, we must also look forward to the mitigation of future bushfire impacts.The Conversation

Paul McInerney, Research scientist, CSIRO; Anu Kumar, Principal Research Scientist, CSIRO; Gavin Rees, Principal Research Scientist, CSIRO; Klaus Joehnk, Principal research scientist, CSIRO, and Tapas Kumar Biswas, Senior scientist, CSIRO

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

Before and after: see how bushfire and rain turned the Macquarie perch’s home to sludge



Mannus Creek in NSW during the 2020 bushfire period.
Luke Pearce, Author provided

Lee Baumgartner, Charles Sturt University; Katie Doyle, Charles Sturt University; Luiz G M Silva, Charles Sturt University; Luke Pearce, and Nathan Ning, Charles Sturt University

This article is a preview of Flora, Fauna, Fire, a multimedia project launching on Monday July 13. The project tracks the recovery of Australia’s native plants and animals after last summer’s bushfire tragedy. Sign up to The Conversation’s newsletter for updates.


The unprecedented intensity and scale of Australia’s recent bushfires left a trail of destruction across Australia. Millions of hectares burned and more than a billion animals were affected or died. When the rains finally arrived, the situation for many fish species went from dangerous to catastrophic.

A slurry of ash and mud washed into waterways, turning freshwater systems brown and sludgy. Oxygen levels plummeted and water quality deteriorated rapidly.

Hundreds of thousands of fish suffocated. It was akin to filling your fish tank with mud and expecting your goldfish to survive.

Take, for example, the plight of the endangered Macquarie perch (Macquaria australasica), an Australian native freshwater fish of the Murray-Darling river system.

A Macquarie perch.
Luke Pearce, Author provided



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A special fish

Macquarie perch were once one of the most abundant fish in the Murray-Darling Basin. Revered by the community and once responsible for supporting extensive Indigenous, recreational, commercial and subsistence fisheries, they are an iconic species found nowhere else in the world. However, they have very specific needs.

Macquarie perch like rocky river sections with clear, fast-flowing water, shaded by trees and bushes on the banks.

Massive change wrought on our rivers over the past century means Macquarie perch are now only found at a handful of locations in the Murray-Darling Basin.

One habitat – Mannus Creek near the NSW Snowy Mountains – is particularly special because it was relatively pristine before the fires. In fact, this creek contained the last population of the threatened Macquarie perch in the NSW Murray catchment. A study in 2017 found a Macquarie perch population that was restricted to a 9km section of the creek but was doing quite well.

That was until bushfire rapidly swept through the catchment in January this year.

Some of us visited the creek three weeks after the fires. The intensity, ferocity and speed of the fires meant nothing was spared. The former forest floor was literally a trail of death and destruction – dead and charred kangaroos, wallabies, deer, possums and birds were everywhere.

All that remained of Mannus Creek was green pools in a blackened landscape, still smouldering days after the fire front passed. We immediately feared for the Macquarie perch we’d sampled, which were quite healthy less than a year before.

To our surprise, some Macquarie perch had survived. But with most of the catchment fully burnt, and no vegetation to stop runoff, we knew it was a ticking time bomb.

A desperate rescue attempt

With little time, we had to remove as many fish as possible from Mannus Creek before the rains arrived. The plan was to create an “insurance population” in case rain caused the water conditions to deteriorate.

We rescued ten fish. Days later, rain washed ash and silt into the channel. Within hours, the once-pristine creek became flowing mud with the consistency of cake mix.

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A government rescue team arrived a few days later to rescue more fish, and despaired at the “wall of ash and mud”.

An ark across Australia

Those ten individual Macquarie perch now live in an “ark” of at-risk species, spanning government and private hatchery facilities.

The ark is housing not only the Macquarie perch but other threatened species too. The rescued individuals, and perhaps their entire species, would have almost certainly perished during runoff events without these interventions.

Now a waiting game begins.

What next for the Macquarie perch?

Nobody knows for sure how many fish survived in Mannus Creek, nor how long it will take for the creek to recover. It could be years.

Ash and mud flow into Lake Macquarie after the fires.
Luke Pearce, Author provided

The challenge now is to support the rescued fish until it’s safe to either return them to the creek, or breed offspring and introduce them to their natural habitat.

Fish must be kept healthy and disease-free in captivity, and enough genetic diversity must be maintained for the population to remain viable.

If these rescued fish are held in captivity for too long, they might die. But equally worrying is that affected waterways may not recover in time to allow reintroduction.




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While maintaining the rescued populations, we must redouble our efforts to improve their natural habitats.

Burnt areas can allow pest plant and animal species to take hold and change habitats, so these threats need to be controlled. Finding similar, unburnt refuge areas is also crucial to prepare for future events and protect ecosystem resilience.

Working through these considerations – and quickly – is essential to giving these species the best hope of survival.

Funding, equipment and human resources are desperately needed to help our rivers recover. But we know that without an effective on-ground intervention, recovery could take decades.

For the iconic Macquarie perch, that would be too late.




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The Conversation


Lee Baumgartner, Professor of Fisheries and River Management, Institute for Land, Water, and Society, Charles Sturt University; Katie Doyle, Freshwater Ecologist, Charles Sturt University; Luiz G M Silva, Freshwater Fish Scientist, Charles Sturt University; Luke Pearce, Fisheries Manager, and Nathan Ning, Freshwater Ecologist, Charles Sturt University

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

Extreme heat and rain: thousands of weather stations show there’s now more of both, for longer



ChameleonsEye/Shutterstock

Jim Salinger, University of Tasmania and Lisa Alexander, UNSW

A major global update based on data from more than 36,000 weather stations around the world confirms that, as the planet continues to warm, extreme weather events such as heatwaves and heavy rainfall are now more frequent, more intense, and longer.

The research is based on a dataset known as HadEX and analyses 29 indices of weather extremes, including the number of days above 25℃ or below 0℃, and consecutive dry days with less than 1mm of rain. This latest update compares the three decades between 1981 and 2010 to the 30 years prior, between 1951 and 1980.

Globally, the clearest index shows an increase in the number of above-average warm days.


Author provided

For Australia, the team found a country-wide increase in warm temperature extremes and heatwaves and a decrease in cold temperature extremes such as the coldest nights. Broadly speaking, rainfall extremes have increased in the west and decreased in the east, but trends vary by season.

In New Zealand, temperate regions experience significantly more summer days and northern parts of the country are now frost-free.




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Extreme temperatures

Unusually warm days are becoming more common throughout Australia. When we compare 1981-2010 with 1951-80, the increase is substantial: more than 20 days per year in the far north of Australia, and at least 10 days per year in most areas apart from the south coast. The increase occurs in all seasons but is largest in spring.

This increase in temperature extremes can have devastating impacts for human health, particularly for older people and those with pre-existing medical conditions. Excessive heat is not only an issue for people living in cities but also for rural communities that have already been exposed to days with temperatures above 50℃.

New Zealanders are also experiencing more days with temperatures of 25℃ or more. The climate stations show the frequency of unusually warm days has increased from 8% to 12% from 1950 to 2018, with an average of 19 to 24 days a year above 25℃ across the country. Unusually warm days, defined as days in the top 10% of historic records for the time of year, are also becoming more common in both countries.

During the summers of 2017-18 and 2018-19, marine heatwaves delivered 32 and 26 (respectively) days above 25℃ nationwide in New Zealand, well above the average of 20 days. This led to accelerated glacial melting in the Southern Alps and major disruption to marine ecosystems, with die-offs of bull kelp around the South Island coast and salmon in aquaculture farms in the Marlborough Sounds.




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More heat, more rain, less frost

In many parts of New Zealand, cold extremes are changing faster than warm extremes.

Between 1950 and 2018, frost days (days below 0℃) have declined across New Zealand, particularly in northern parts of the country which has now become frost-free, enabling farmers to grow subtropical pasture grasses. At the same time, crops that require winter frosts to set fruit are no longer successful, or can only be grown with chemical treatments (currently under review) that simulate winter chilling.

Across New Zealand, the heat available for crop growth during the growing season is increasing, which means wine growers have to shift varieties further south.

In Australia, the situation is more complicated. In many parts of northern and eastern Australia, there has also been a large decrease in the number of cold nights. But in parts of southeast and southwest Australia, frost frequency has stabilised, or even increased in places, since the 1980s.

These areas have seen a large decrease in winter rainfall in recent decades. The higher number of dry, clear nights in winter, favourable for frost formation, has cancelled out the broader warming trend.




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In Australia, extreme rainfall has become more frequent in many parts of northern and western Australia, especially the northwest, which has become wetter since the 1960s. In eastern and southern Australia the picture is more mixed, with little change in the number of days with 10mm or more of rain, even in those regions where total rainfall has declined.

In New Zealand, more extremely wet days contribute towards the annual rainfall total in the east of the North Island, with a smaller increase in the west and south of the South Island. For Australia, there are significant drying trends in parts of the southwest and northeast, but little change elsewhere.

Extremes of temperature and precipitation can have dramatic effects, as seen during two marine heatwaves in New Zealand and the hottest, driest year in Australia during 2019.The Conversation

Jim Salinger, Honorary Associate, Tasmanian Institute for Agriculture, University of Tasmania and Lisa Alexander, Chief Investigator ARC Centre of Excellence for Climate System Science and Associate Professor Climate Change Research Centre, UNSW

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

How drought-breaking rains transformed these critically endangered woodlands into a flower-filled vista



Wildflowers blooming in box gum grassy woodland
Jacqui Stol, Author provided

Jacqui Stol, CSIRO; Annie Kelly, and Suzanne Prober, CSIRO

In box gum grassy woodlands, widely spaced eucalypts tower over carpets of wildflowers, lush native grasses and groves of flowering wattles. It’s no wonder some early landscape paintings depicting Australian farm life are inspired by this ecosystem.

But box gum grassy woodlands are critically endangered. These woodlands grow on highly productive agricultural country, from southern Queensland, along inland slopes and tablelands, into Victoria.

Many are degraded or cleared for farming. As a result, less than 5% of the woodlands remain in good condition. What remains often grows on private land such as farms, and public lands such as cemeteries or travelling stock routes.




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Very little is protected in public conservation reserves. And the recent drought and record breaking heat caused these woodlands to stop growing and flowering.

But after Queensland’s recent drought-breaking rain earlier this year, we surveyed private farmland and found many dried-out woodlands in the northernmost areas transformed into flower-filled, park-like landscapes.

And landholders even came across rarely seen marsupials, such as the southern spotted-tail quoll.

Native yellow wildflowers called ‘scaly buttons’ bloom on a stewardship site.
Jacqui Stol, Author provided

Huge increase in plant diversity

These surveys were part of the Australian government’s Environmental Stewardship Program, a long-term cooperative conservation model with private landholders. It started in 2007 and will run for 19 years.

We found huge increases in previously declining native wildflowers and grasses on the private farmland. Many trees assumed to be dying began resprouting, such as McKie’s stringybark (Eucalyptus mckieana), which is listed as a vulnerable species.

This newfound plant diversity is the result of seeds and tubers (underground storage organs providing energy and nutrients for regrowth) lying dormant in the soil after wildflowers bloomed in earlier seasons. The dormant seeds and tubers were ready to spring into life with the right seasonal conditions.

For example, Queensland Herbarium surveys early last year, during the drought, looked at a 20 metre by 20 metre plot and found only six native grass and wildflower species on one property. After this year’s rain, we found 59 species in the same plot, including many species of perennial grass (three species jumped to 20 species post rain), native bluebells and many species of native daisies.




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On another property with only 11 recorded species, more than 60 species sprouted after the extensive rains.

In areas where grazing and farming continued as normal (the paired “control” sites), the plots had only around half the number of plant species as areas managed for conservation.

Spotting rare marsupials

Landowners also reported several unusual sightings of animals on their farms after the rains. Stewardship program surveyors later identified them as two species of rare and endangered native carnivorous marsupials: the southern spotted-tailed quoll (mainland Australia’s largest carnivorous marsupial) and the brush-tailed phascogale.

The population status of both these species in southern Queensland is unknown. The brush-tailed phascogale is elusive and rarely detected, while the southern spotted-tailed quolls are listed as endangered under federal legislation.

Until those sightings, there were no recent records of southern spotted-tailed quolls in the local area.

A spotted tailed quoll caught in a camera trap.
Sean Fitzgibbon, Author provided

These unusual wildlife sightings are valuable for monitoring and evaluation. They tell us what’s thriving, declining or surviving, compared to the first surveys for the stewardship program ten years ago.

Sightings are also a promising signal for the improving condition of the property and its surrounding landscape.

Changing farm habits

More than 200 farmers signed up to the stewardship program for the conservation and management of nationally threatened ecological communities on private lands. Most have said they’re keen to continue the partnership.

The landholders are funded to manage their farms as part of the stewardship program in ways that will help the woodlands recover, and help reverse declines in biodiversity.

For example, by changing the number of livestock grazing at any one time, and shortening their grazing time, many of the grazing-sensitive wildflowers have a better chance to germinate, grow, flower and produce seeds in the right seasonal conditions.




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They can also manage weeds, and not remove fallen timber or loose rocks (bushrock). Fallen timber and rocks protect grazing-sensitive plants and provide habitat for birds, reptiles and invertebrates foraging on the ground.

Cautious optimism

So can we be optimistic for the future of wildlife and wildflowers of the box gum grassy woodlands? Yes, cautiously so.

Landholders are learning more about how best to manage biodiversity on their farms, but ecological recovery can take time. In any case, we’ve discovered how resilient our flora and fauna can be in the face of severe drought when given the opportunity to grow and flourish.

The rare hooded robin has also been recorded on stewardship sites during surveys.
Micah Davies, Author provided

Climate change is bringing more extreme weather events. Last year was the warmest on record and the nation has been gripped by severe, protracted drought. There’s only so much pressure our iconic wildlife and wildflowers can take before they cross ecological thresholds that are difficult to bounce back from.

More government programs like this, and greater understanding and collaboration between scientists and farmers, create a tremendous opportunity to keep changing that trajectory for the better.The Conversation

Jacqui Stol, Senior Experimental Scientist, Ecologist, CSIRO Land and Water, CSIRO; Annie Kelly, Senior Ecologist, and Suzanne Prober, Senior Principal Research Scientist, CSIRO

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

Why drought-busting rain depends on the tropical oceans


Andrew King, University of Melbourne; Andy Pitman, UNSW; Anna Ukkola, Australian National University; Ben Henley, University of Melbourne, and Josephine Brown, University of Melbourne

Recent helpful rains dampened fire grounds and gave many farmers a reason to cheer. But much of southeast Australia remains in severe drought.

Australia is no stranger to drought, but the current one stands out when looking at rainfall records over the past 120 years. This drought has been marked by three consecutive extremely dry winters in the Murray-Darling basin, which rank in the driest 10% of winters since 1900.

Despite recent rainfall the southeast of Australia remains in the grip of a multi-year drought.
Bureau of Meteorology

So what’s going on?

There has been much discussion on whether human-caused climate change is to blame. Our new study explores Australian droughts through a different lens.




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Rather than focusing on what’s causing the dry conditions, we investigated why it’s been such a long time since we had widespread drought-breaking rain. And it’s got a lot to do with how the temperature varies in the Pacific and Indian Ocean.

Our findings suggest that while climate change does contribute to drought, blame can predominately be pointed at the absence of the Pacific Ocean’s La Niña and the negative Indian Ocean Dipole – climate drivers responsible for bringing wetter weather.

Understanding the Indian Ocean Dipole.

What’s the Indian Ocean Dipole?

As you may already know, the Pacific Ocean influences eastern Australia’s climate through El Niño conditions (associated with drier weather) and La Niña conditions (associated with wetter weather).

The lesser known cousin of El Niño and La Niña across the Indian Ocean is called the Indian Ocean Dipole. This refers to the difference in ocean temperature between the eastern and western sides of the Indian Ocean. It modulates winter and springtime rainfall in southeastern Australia.




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When the Indian Ocean Dipole is “negative”, there are warmer ocean temperatures in the east Indian Ocean, and we see more rain over much of Australia. The opposite is true for “positive” Indian Ocean Dipole events, which bring less rain.

The Murray-Darling Basin experiences high rainfall variability, with decade-long droughts common since observations began. The graph shows seasonal rainfall anomalies from a 1961-1990 average with major droughts marked.
Author provided

What does it mean for the drought?

When the drought started to take hold in 2017 and 2018, we didn’t experience an El Niño or strongly positive Indian Ocean Dipole event. These are two dry-weather conditions we might expect to see at the start of a drought.

Rather, conditions in the Pacific and Indian Oceans were near neutral, with little to suggest a drought would develop.

So why are we in severe, prolonged drought?

The problem is we haven’t had either a La Niña or a negative Indian Ocean Dipole event since winter 2016. Our study shows the lack of these events helps explain why eastern Australia is in drought.

For the southeast of Australia in particular, La Niña or negative Indian Ocean Dipole events provide the atmosphere with suitable conditions for persistent and widespread rainfall to occur. So while neither La Niña or a negative Indian Ocean Dipole guarantee heavy rainfall, they do increase the chances.

What about climate change?

While climate drivers are predominately causing this drought, climate change also contributes, though more work is needed to understand what role it specifically plays.

Drought is more complicated and multidimensional than simply “not much rain for a long time”. It can be measured with a raft of metrics beyond rainfall patterns, including metrics that look at humidity levels and evaporation rates.

What we do know is that climate change can exacerbate some of these metrics, which, in turn, can affect drought.




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Climate change might also influence climate drivers, though right now it’s hard to tell how. A 2015 study suggests that under climate change, La Niña events will become more extreme. Another study from earlier this month suggests climate change is driving more positive Indian Ocean Dipole events, bringing even more drought.

Unfortunately, regional-scale projections from climate models aren’t perfect and we can’t be sure how the ocean patterns that increase the chances of drought-breaking rains will change under global warming. What is clear is there’s a risk they will change, and strongly affect our rainfall.

Putting the drought in context

Long periods when a La Niña or a negative Indian Ocean Dipole event were absent characterised Australia’s past droughts. This includes two periods of more than three years that brought us the Second World War drought and the Millennium drought.

The longer the time without a La Niña or negative Indian Ocean Dipole event, the more likely the Murray-Darling Basin is in drought.

In the above graph, the longer each line continues before stopping, the longer the time since a La Niña or negative Indian Ocean Dipole event occurred. The lower the lines travel, the less rainfall was received in the Murray Darling basin during this period. This lets us compare the current drought to previous droughts.

During the current drought (black line) we see how the rainfall deficit continues for several years, almost identically to how the Millennium drought played out.

But then the deficit increases strongly in late 2019, when we had a strongly positive Indian Ocean Dipole.

So when will this drought break?

This is a hard question to answer. While recent rains have been helpful, we’ve developed a long-term rainfall deficit in the Murray-Darling Basin and elsewhere that will be hard to recover from without either a La Niña or negative Indian Ocean Dipole event.




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The most recent seasonal forecasts don’t predict either a negative Indian Ocean Dipole or La Niña event forming in the next three months. However, accurate forecasts are difficult at this time of year as we approach the “autumn predictability barrier”.

This means, for the coming months, the drought probably won’t break. After that, it’s anyone’s guess. We can only hope conditions improve.The Conversation

Andrew King, ARC DECRA fellow, University of Melbourne; Andy Pitman, Director of the ARC Centre of Excellence for Climate System Science, UNSW; Anna Ukkola, Research Fellow, Australian National University; Ben Henley, Research Fellow in Climate and Water Resources, University of Melbourne, and Josephine Brown, Lecturer, University of Melbourne

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

‘It is quite startling’: 4 photos from space that show Australia before and after the recent rain



National Map

Sunanda Creagh, The Conversation

Editor’s note: These before-and-after-images from several sources –NASA’s Worldview application, National Map by Geoscience Australia and Digital Earth Australia – show how the Australian landscape has responded to huge rainfall on the east coast over the last month. We asked academic experts to reflect on the story they tell:


Warragamba Dam, Sydney

Stuart Khan, water systems researcher and professor of civil and environmental engineering.

This map from Digital Earth Australia shows a significant increase in water stored in Lake Burragorang. Lake Burragorang is the name of water body maintained behind the Warragamba Dam wall and the images show mainly the southern source to the lake, which is the Wollondilly River. A short section of the Coxs River source is also visible at the top of the images.

The Warragamba catchment received around 240mm of rain during the second week of February, which produced around 1,000 gigalitres (GL) of runoff to the lake. This took the water storage in the lake from 42% of capacity to more than 80%.

Unlike a typical swimming pool, the lake does not generally have vertical walls. Instead, the river valley runs deeper in the centre and more shallow around the edges. As water storage volumes increase, so does the surface area of water, which is the key feature visible in the images.

Leading up to this intense rainfall event, many smaller events occurred, but failed to produce any significant runoff. The catchment was just too dry. Dry soils act like a sponge and soak up rainfall, rather than allowing it to run off to produce flows in waterways.

The catchment is now in a much wetter state and we can expect to see smaller rainfall events effectively produce further runoff. So water storage levels should be maintained, at least in the short term.

However in the longer term, extended periods of low rainfall and warm temperatures will make this catchment drier.

In the absence of further very intense rainfall events, Sydney will lapse back into drought and diminishing water storages.

This pattern of decreasing storage, broken only by very intense rainfall, can be observed in Sydney’s water storage history.

It is a pattern likely to be exacerbated further in future.


Wivenhoe Dam, Brisbane

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Stuart Khan, water systems researcher and professor of civil and environmental engineering.

Lake Wivenhoe is the body of water maintained behind Wivenhoe Dam wall in southeast Queensland. It is the main water storage for Brisbane as well as much of surrounding southeast Queensland.

This image from National Map shows a visible change in colour from brown to green in the region around the lake. It is quite startling.

This is especially the case to the west of the lake, in mountain range areas such as Toowoomba, Warwick and Stanthorpe. Many of these areas were in very severe drought in January. Stanthorpe officially ran out of water. The February rain has begun to fill many important water storage areas and completely transformed the landscape.

Unfortunately, this part of Australia is highly prone to drought and we can expect to see this pattern recur over coming decades.

Much climate science research indicates more extreme weather events in future. That means more extreme high temperatures, more intense droughts and more severe wet weather.

There are many challenges ahead for Australian water managers as they seek to overcome the inevitable booms and busts of future water availability.




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Australia-wide

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Grant Williamson, Research Fellow in Environmental Science, University of Tasmania

It’s clear from this map above, from NASA Worldview, the monsoon has finally arrived in northern Australia and there’s been quite a lot of rain.

On the whole, you can see how rapidly the Australian environment can respond to significant rainfall events.

It’s important to remember that most of that greening up will be the growth of grasses, which respond more rapidly after rain.

The forests that burned will not be responding that quickly. The recovery process will be ongoing and within six months to a year you’d expect to see significant regrowth in the eucalyptus forests.

Other more fire-sensitive vegetation, like rainforests, may not exhibit the same sort of recovery.




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Grant Williamson, Research Fellow in Environmental Science, University of Tasmania

This slider from National Map shows both fire impact, and greening up after rain.

On the left – an area west of Cooma on December 24 – you can see the yellow treeless areas, indicating the extent of the drought, and the dark green forest vegetation. This image also shows quite a lot of smoke, as you’d expect.

On the right – the area on February 22 – a lot of those yellow areas are now significantly greener after the rain. However, some of those dark green forest areas are now brown or red, where they have been burnt.

It’s clear there is a long road ahead for recovery of these forests that were so badly burned in the recent fires but they will start resprouting in the coming months.

Grant Williamson is a Tasmania-based researcher with the NSW Bushfire Risk Management Research Hub.The Conversation


Sunanda Creagh, Head of Digital Storytelling, The Conversation

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

Heavy rains are great news for Sydney’s dams, but they come with a big caveat


Ian Wright, Western Sydney University and Jason Reynolds, Western Sydney University

Throughout summer, Sydney’s water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.

But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.

This is great news for the city, but it comes with a big caveat. Floodwaters will undoubtedly wash bushfire debris into reservoirs – possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.

Reservoirs filled with rain

The water level of Sydney’s massive Lake Burragorang – the reservoir behind Warragamba Dam – rose by more than 11 meters this week. Warragamba supplies more than 80% of Sydney’s water.

Other Sydney water storages, including Nepean and Tallowa dams, are now at 100%.
WaterNSW report that 865,078 megalitres of extra water has been captured this week across all Greater Sydney’s dams.

This dwarfs the volume of water produced by Sydney’s desalination plant, which produces 250 megalitres a day when operating at full capacity. Even at this rate, it would take more than 3,400 days (or nine years) to match the volume of water to added to Sydney’s supply this week.

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The Warragamba Dam before the drought and after the recent heavy rains.

But then comes the pollution

Thankfully, the rain appears to have extinguished bushfires burning in the Warragamba catchment for months.

But the water will also pick up bushfire debris and wash it into dams.

Over the summer, bushfires burnt about 30% of Warragamba Dam’s massive 905,000 hectare water catchment, reducing protective ground cover vegetation. This increases the risk of soil erosion. Rain will wash ash and sediment loads into waterways – adding more nitrogen, phosphorous and organic carbon into water storages.




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Waterways and ecosystems require nutrients like phosphorous and nitrogen, but excess nutrients aren’t a good thing. They bring contamination risks, such as the rapid growth of toxic blue-green algae.

Drinking water catchments will always have some degree of contamination and water treatment consistently provides high quality drinking water. But poor water quality after catchment floods is not without precedent.

We’ve seen this before

In August 1998, extreme wet weather and flooding rivers filled the drought-affected Warragamba Dam in just a few days.

This triggered the Cryptosporidium crisis, when the protozoan parasite and the pathogen Giardia were detected in Sydney’s water supplies. It triggered health warnings, and Sydneysiders were instructed to boil water before drinking it. This event did not involve a bushfire.




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The Canberra bushfires in January 2003 triggered multiple water quality problems. Most of the region’s Cotter River catchments, which hold three dams, were burned. Intense thunderstorms in the months after the bushfire washed enormous loads of ash, soil and debris into catchment rivers and water reservoirs.

This led to turbidity (murkiness), as well as iron, manganese, nitrogen, phosphorus and carbon in reservoir waters. The inflow of organic material also depleted dissolved oxygen which triggered the release of metals from reservoir sediment. At times, water quality was so poor it couldn’t be treated and supplied to consumers.

The ACT Government was forced to impose water restrictions, and built a A$38 million water treatment plant.

Have we come far enough?

Technology in water treatment plants has developed over the past 20 years, and water supply systems operates according to Australian drinking water guidelines.

Unlike the 1998 Sydney water crisis, WaterNSW, Sydney Water and NSW Health now have advanced tests and procedures to detect and manage water quality problems.

In December last year, WaterNSW said it was aware of the risk bushfires posed to water supplies, and it had a number of measures at its disposal, including using booms and curtains to isolate affected flows.

However at the time, bushfire ash had already reportedly entered the Warragamba system.

The authors crossing the Coxs River during very low flow last September.
Author provided

Look to recycled water

Sydney’s water storages may have filled, but residents should not stop saving water. We recommend Level 2 water restrictions, which ban the use of garden hoses, be relaxed to Level 1 restrictions which ban most sprinklers and watering systems, and the hosing of hard surfaces.

While this measure is in place, longer term solutions can be explored. Expanding desalination is a popular but expensive option, however greater use of recycled wastewater is also needed.




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Highly treated recycled water including urban stormwater and even treated sewage should be purified and incorporated into the water supply. Singapore is a world leader and has proven the measure can gain community acceptance.

It’s too early to tell what impact the combination of bushfires and floods will have on water storages. But as extreme weather events increase in frequency and severity, all options should be on the table to shore up drinking water supplies.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University and Jason Reynolds, Senior Lecturer in Geochemistry, Western Sydney University

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