1,600 years ago, climate change hit the Australian Alps. We studied ancient lake mud to learn what happened


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Zoë Thomas, UNSW; Haidee Cadd, University of Wollongong, and Larissa Schneider, Australian National UniversityIf you’ve ever visited Australia’s highest peak — Mount Kosciuszko — you might remember the long uphill trek to the summit past some of Australia’s most picturesque and rugged landscapes. Vibrant snow gums, boardwalks with meadows of exquisite alpine plants, and blinding patches of snow.

As you approach the summit, a quartet of stunning blue lakes appear, created by glaciers during the last ice age that carved new valleys out of the mountain.

Lakes like these are windows to the past, offering an opportunity to understand how our climate and environment has changed over hundreds to thousands of years. One such lake, Club Lake — so-named for its resemblance to a suit in a deck of cards — was the focus of our new study.

After studying the lake’s sediment, we learned the Australian Alps experienced a sudden climate change about 1,600 years ago that brought a long spell of warmer conditions. What makes this sudden warming event particularly interesting is that it bears striking similarity to today.

Climate change in the Australian Alps

The Australian alpine region is the traditional home of a number of Aboriginal groups, including the Ngarigo, Walgalu and Djilamatang people. It is also home to highly diverse flora and fauna that occur nowhere else, from billy buttons (Craspedia costiniana) known for their vibrant yellow rosette of tiny flowers, to the broad-toothed rat and its chubby cheeks.

But this unique wildlife is under immense threat from climate change.

By 2100, Australia may warm by at least 4℃, with bushfires becoming more frequent and devastating. The fragile alpine ecosystem will be hit particularly hard by these changes.




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Many of Australia’s alpine species are already near their climatic limits, and are constrained by altitude. They’re at risk of becoming regionally extinct if their climatic thresholds are exceeded. As the temperature warms, treelines move upslope to cooler temperatures, pushing alpine flora and fauna to higher elevations. At some point they can go no higher — they’re squeezed out of their niche.

The critically endangered mountain pygmy-possum, for example, relies on the seasonal snowpack for winter hibernation, but increased temperatures are limiting this habitat.

A dip into the past

Our study showed Club Lake holds vital clues to the link between rising temperatures, loss of native plant species and more frequent fires in the Snowy Mountains.

Lake sediments are used all over the world as indicators of climate and environmental change because of the unique way they trap material. A body of water can act as a seal that ensures sediments are largely undisturbed over time.

We extracted sediments from the bottom of Club Lake to a depth of 35 centimetres. This equates to about 3,500 years of history, approximately 100 years for each centimetre.

Club-shaped lake in the mountains
Club Lake in Mt Kosciuszko.
Shutterstock

To work out how temperatures have changed over this time, we looked for the presence of molecular fossils, called “lipid biomarkers”. Analysing these biomarkers in the laboratory can tell us what the temperature in the environment was like, hundreds or thousands of years ago.

In the 3,500 years we examined, we detected a gradual warming trend. Superimposed on this, we found a sudden warming event that started 1,600 years ago, and lasted about six centuries. We suspect it was due to an atmospheric phenomenon linking higher tropical sea surface temperatures to southeastern Australia.

We’re not yet sure how much of Australia was affected by this warming, but other research from 2018 measured similar temperature changes in stalagmites from the Yarrangobilly caves 50 kilometres away.

Alpine snow gums (Eucalyptus pauciflora)
Zoë Thomas

What happened during this climate change?

During this unusual warmth, alpine herbs and shrubs declined, while the abundance of trees, particularly eucalyptus, increased. We know this by looking at grains of pollen preserved at different depths within the lake sediment samples, which indicates what types of plants were growing nearby.

We also found small particles of charcoal, produced by bushfires, embedded within the sediment layers. This showed the changes in vegetation also coincided with greater fire activity.

What surprised us most, however, was discovering a large increase in mercury at this time.

Mercury, which occurs naturally in the environment, is the only metal that’s liquid at room temperature, and is particularly sensitive to temperature changes. Higher temperatures enhance mercury deposition from the atmosphere, and our study shows a five-fold increase in mercury flux 1,600 years ago.

Alpine herbfields.
Nicola Pain

Industrial activities over the last 150 years, such as burning coal, have increased the abundance of mercury significantly. Our findings suggest future climate change is likely to increase the risk of mercury exposure not just in cities, but also in the seemingly remote Australian alpine environment.

Mercury contamination is a significant public health and environmental problem. At certain levels it’s poisonous to the nervous system, and it does not easily degrade.




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What can we do?

Insights from the past can help governments, environmental agencies, and scientists come up with effective strategies to protect the vulnerable flora and fauna of the Australian Alps. But it’s not just changes in climate they’ll have to contend with in future.

There are other perils, such as soil erosion and habitat fragmentation from the legacy of sheep and cattle grazing, and tourism. Invasive pests and pathogens are likely to further reduce the resilience of these alpine ecosystems.

Feral horses graze near a tree
Feral horses are a significant threat to native wildlife in Australia’s alpine region.
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Restoration programs over the last 50 years have aimed to revitalise the natural vegetation in the Kosciuszko National Park following 135 years of grazing — finally banned in 1969 — and the environmental damage caused by the Snowy River Hydro-Electric scheme.

More recently, the federal government has committed A$3.5 million towards recovery from the devastating 2019-2020 bushfires. Incorporating Aboriginal knowledge into mainstream fire management is essential for tackling future crises.

This is the critical time for climate action to protect this unique and iconic Australian landscape.




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The Conversation


Zoë Thomas, ARC DECRA Fellow, UNSW; Haidee Cadd, Research associate, University of Wollongong, and Larissa Schneider, DECRA fellow, Australian National University

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

‘It is not easy’: how science and courage saved the stunning Australian Alps



National Library of Australia

Philip Gibbons, Australian National University

Most people probably associate the Australian Alps with skiing and snow. Others might think of the Man from Snowy River legend or the engineering feats of the Snowy Hydro-Electric Scheme.

But few people know the region’s history of exploitation and overuse, nor the courage of those who fought to save this precious wilderness area. A new book, Kosciuszko: A Great National Park, tells that important story. The result, by authors Deirdre Slattery and Graeme L. Worboys, is a positive yet cautionary tale.

Today, the park is largely protected – yet threats such as ski tourism, feral horses and the Snowy 2.0 scheme still loom. And climate change has left the region highly vulnerable, as shown by declining snow depths and a massive bushfire that tore through the Snowy Mountains last summer.

The book shows how Kosciuszko National Park is the product of robust science and hard-fought battles by dedicated individuals – battles that continue to this day.

A ranger-guided tour leaving for the Kosciuszko summit in 1964.
A ranger-guided tour leaving for the Kosciuszko summit in 1964.
Gare collection in Kosciuszko: A Great National Park

A long history of occupation

The Australian Alps in southeast New South Wales is the traditional home of three Aboriginal groups: the Ngarigo, Walgalu and Djilamatang people. It is home to Australia’s highest peak, Mount Kosciuszko.

The book describes how squatters with cattle occupied the region from the 1820s. By 1840, the Snowy region had been stocked with 200,000 sheep, 75,000 cattle and 3,000 horses which grazed in the mountains each summer.




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The discovery of gold in 1860 brought another 10,000 people to the Snowy Mountains. By the turn of the 20th century, the mountains were also a playground for recreation. Hotel Kosciusko, with 93 bedrooms, a ballroom, museum, skating rink and tennis courts, catered for an upmarket clientele.

In 1949 the mountains became the site for the Snowy Mountains Hydro-Electric Scheme: 16 dams, 80 kilometres of aqueducts and more than 140 kilometres of tunnels.

By then, the signs of overuse were evident. Soils were eroding, streams became silted and unique alpine flora was diminishing.

Cattle grazing at Club Lake believed to be during the Federation Drought (1897-1903).
Cattle grazing at Club Lake believed to be during the Federation Drought (1897-1903).
Kerry Studio/Costin collection in Kosciuszko: A Great National Park.

The long conservation fight

Tannat William Edgeworth David, a professor at the University of Sydney, was one of the first to document the unique values of the Snowy Mountains and call for their protection.

In the 1800s, the notion that an ice age once gripped Australia was considered preposterous. The book tells how David and colleagues put the matter “absolutely beyond dispute” when they mapped, on Kosciuszko’s main range, the undeniable signature left by glaciers.

In the early 1900s, David urged that the alpine area be preserved:

[I]t would be wise policy, in the interest of people and of science, to reserve from occupation and even from the depasturing of stock, all the highest points of our alpine plateau, so that this floral wonderland may be preserved intact for posterity…

It took almost 50 years before this advice was heeded. Kosciuszko State Park — later Kosciuszko National Park – was proclaimed in 1944. A decade of further scientific research led to the end of summer grazing leases above 1,350 metres in 1958.

One of the first park managers was Neville Gare. As the book notes, Gare quickly learned that feelings over management of the mountains ran deep. Soon after rangers started impounding stock found illegally in the park, an effigy of a park ranger swinging from a hangman’s noose was installed on the veranda of the Jindabyne Hotel.




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In 1950, Gare resisted a plan by head of the Ski Tourers Association, Charles Anton, to build a network of ski lodges. The book recounts how the tensions culminated at a public function when Anton snipped Gare’s tie in half to “indicate his indifference to Gare’s authority”. Some lodges were later built.

In his unpublished memoir, Gare wrote “it is not easy to conserve something and use it too”. In future years, this observation would prove all too true.

Stock illegally moved into the park after grazing leases ended in 1958.
Stock illegally moved into the park after grazing leases ended in 1958.
Alec Costin in Kosciuszko: A Great National Park

Ongoing battles

Gare and the Kosciusko State Park Trust developed the first formal plan of management for the park in 1965. The park was divided into zones for different uses: wilderness, conservation of exceptional natural and historic features, development, hydro-electricity and tourism.

This zoning was radical thinking at the time but has since been widely adopted in park management across Australia.

The plan of management for Kosciuszko National Park has been frequently amended to accommodate more tourism facilities, and the threat of further development is ever-present. As the authors note, further pressure is also coming via Snowy 2.0, a A$5 billion proposal to expand the current hydroelectric scheme.

Climate change is also a threat. Rising temperatures have triggered a 15% decline in the annual maximum snow depth, relative to the 1961-90 average.

Skiers at Perisher Valley
Climate change is reducing the snow depth in the region.
Perisher/AAP

Climate change is also making the threat of bushfires worse. In January, the massive Adaminaby Complex fire burned through more than 93,000 hectares in the Snowy region, affecting swathes of bush. It also devastated populations of several threatened species, including the corroboree frog and the stocky galaxias fish.

And the lethal chytrid fungus, introduced to Australia, has pushed the park’s southern corroboree frog to the brink of extinction.




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In 2018, the NSW government declared feral horses in the park a protected species. The population has quickly grown to about 19,000, representing a considerable threat to several species.

The book reminds us that today, as throughout history, Kosciuszko National Park needs protecting. And key to that are courageous, committed individuals – and robust science.The Conversation

A scenic view of the Snowy Mountains
The Snowy Mountains are protected, but threats remain.
Schopier/Wikimedia

Philip Gibbons, Professor, Australian National University

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

Fire almost wiped out rare species in the Australian Alps. Feral horses are finishing the job



Feral horses are destroying what little threatened species habitat was spared from bushfire.
Invasive Species Council

Jamie Pittock, Australian National University

On Friday I flew in a helicopter over the fire-ravaged Kosciuszko National Park. I was devastated by what I saw. Cherished wildlife species are at grave risk of extinction: those populations the bushfires haven’t already wiped out are threatened by thousands of feral horses trampling the land.

The New South Wales park occupies the highest mountain range in Australia and is home to plants and animals found nowhere else in the world. Many of these species are threatened, and their survival depends on protecting habitat as best we can.




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Kosciuszko National Park provides habitat for two species of corroboree frog (critically endangered), the alpine she-oak skink (endangered), broad-toothed rat (vulnerable) and stocky galaxias (a critically endangered native fish), among other threatened species.

As the climate has warmed, the cool mountain habitat of these species is shrinking; bushfires have decimated a lot of what was left. Feral horses now threaten to destroy the remainder, and an urgent culling program is needed.

Devastation as far as the eye can see on the burnt western face of Kosciuszko National Park.
Jamie Pittock

Not a green leaf in sight

Australia’s plants and ecosystems did not evolve to withstand trampling by hard-hooved animals, or their intensive grazing. Unfortunately, the New South Wales government has allowed the population of feral horses in the park to grow exponentially in recent years to around 20,000.

I flew over the northern part of the park with members of the Invasive Species Council, who were conducting an urgent inspection of the damage. Thousands of hectares were completely incinerated by bushfires: not a green leaf was visible over vast areas. A cataclysm has befallen the western face of the mountains and tablelands around Kiandra and Mount Selwyn.




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Further north and east of Kiandra the fires were less intense and burnt patchily. On Nungar Plain the grassland and peat wetlands were only lightly burnt, and the first green shoots were already visible along the wetlands of the valley floor.

At first, I wondered if the fires may have spared two animals which live in tunnels in the vegetation on the sub-alpine high plains: the alpine she-oak skink and broad-toothed rat (which, despite the name is a cute, hamster-like creature).

The hamster-like broad toothed rat.
Flickr

But not only was their understory habitat burnt, a dozen feral horses were trampling the peat wetlands and eating the first regrowth.

On the unburnt or partially burnt plains a few ridges over, 100 or more horses were mowing down the surviving vegetation.

Precarious wildlife refuges

Next we flew over a small stream that holds the last remaining population of a native fish species, the stocky galaxias. A small waterfall is all that divides the species from the stream below, and the jaws of the exotic trout which live there.

The aftermath of the fires means the last refuge of the stocky galaxias is likely to become even more degraded.

Over the years, feral horses have carved terraces of trails into the land causing erosion and muddying the stream bank. As more horses congregate on unburnt patches of vegetation after the fires, more eroded sediment will settle on the stream bed and fill the spaces between rocks where the fish shelter. Ash runoff entering the stream may clog the gills of the fish, potentially suffocating them.

An Alpine she-oak skink.
Renee Hartley



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Many key wetland habitats of the southern and northern corroboree frogs have also been burnt. These striking yellow and black frogs nest in wetland vegetation.

A corroboree frog.
Flickr

We hovered over a key wetland for the northern corroboree frog that had not been burnt, deep in the alpine forest. A group of feral horses stood in it. They had created muddy wallows, trampled vegetation and worn tracks that will drain the wetland if their numbers are not immediately controlled.

Horses out of control

Five years ago a survey reported about 6,000 feral horses roaming in Kosciuszko National Park. By 2019, the numbers had jumped to at least 20,000.

We saw no dead horses from the air. Unlike our native wildlife, most appear to have escaped the fires.




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Flying down the upper Murrumbidgee River’s Long Plain, I saw large numbers of feral horses gathered in yet more wetlands. Displaced by the fires to the south and west, they were already trampling the mossy and heathy wetlands that store and filter water in the headwaters.

The Murrumbidgee River is a key water source for south-east Australia. The horses stir up sediment and defecate in the water. They create channels which drain and dry the wetlands, exposing them to fire.

One-third of Kosciuszko National Park has been burnt out and at the time of writing the fires remain active. Feral horses are badly compounding the damage.

If we don’t immediately reduce feral horse numbers, the consequences for Kosciuszko National Park and its unique Australian flora and fauna will be horrendous.

Responsible managers limit the numbers of livestock on their lands and control feral animals. The NSW government must repeal its 2018 legislation protecting feral horses in Kosciuszko National Park, and undertake a responsible control program similar to those of the Australian Capital Territory and Victorian governments.

Without an emergency cull of feral horses in Kosciuszko National Park, burnt vegetation may not fully recover and threatened species will march further towards extinction.The Conversation

Jamie Pittock, Professor, Fenner School of Environment & Society, Australian National University

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

Double trouble as feral horse numbers gallop past 25,000 in the Australian Alps



Feral horses are a growing problem for the NSW government.
Shutterstock/Constantin Stanciu

Don Driscoll, Deakin University; David M Watson, Charles Sturt University, and Euan Ritchie, Deakin University

Feral horse numbers have more than doubled in the past five years in the Australian Alps, according to results just released from the Australian Alps Feral Horse Aerial Survey. In one of the three survey blocks, North Kosciuszko, feral horse numbers have risen from an estimated 3,255 in 2014 to 15,687 in 2019, a near five-fold increase.

Scientists warned the government that very high numbers of horses would be the inevitable consequence of its inaction over horse management.

With no horses removed in 2017 or 2018, and only 99 removed this year, the population has been allowed to grow at about 23% per year, close to the maximum of about 25% known for feral horses.

More than just allowing numbers to increase, the NSW parliament legislated to protect feral horses within Kosciuszko National Park, effectively prioritising the preservation of horse populations over native alpine species and environmental values, where they are in conflict.

This was despite the strong advice from scientists, and amid substantial controversy around the origins and timing of the bill.

A potentially fatal feral horse problem

High feral horse numbers forced the closure of the popular Blue Waterholes campground in November, after substantial risks and several injuries to visitors were reported. Freedom of information requests were needed to bring to light crashes between cars and feral horses in Kosciuszko.

Despite the NSW government trying to keep this information from reaching the public, several incidents of feral horses being struck by vehicles have now been reported.

The community group Reclaim Kosci has warned it is only a matter of time before someone is killed in a collision with a feral horse unless numbers are drastically and rapidly reduced.

Government warned of potentially deadly car crashes with feral horses.
Shutterstock/Trevor Charles Graham

Besides impacts on people, the lack of effective feral horse policy in NSW has now set the stage for another mass animal welfare disaster.

With an estimated 25,318 feral horses distributed across the surveyed area (more than 7,400 square kilometres) of the Australian Alps, many thousands of horses will face starvation when the region next burns. This is predictable, inevitable and tragically also completely avoidable had effective feral horse control been implemented.

The prolonged drought hitting Australia has worsened the impacts of horses in the high country. Plants already struggling to survive are being trampled and grazed, and areas around standing water resemble feedlots.

These impacts will worsen over summer, both for the national park and the horses themselves, with herds suffering in the heat and struggling to survive. Horses starved to death along the snowy river in Kosciuszko in 2018.

Now many more animals are at risk of this fate because scientifically-supported solutions have been dismissed by NSW deputy premier John Barilaro.

Natural wildlife threatened

Evidence presented at the Kosciuszko Science Conference and research published earlier this year showed how a broad range of Alpine species and ecosystems were being affected by feral horses. These effects will now be more intense and occur across more of Australia’s ecologically sensitive and biodiverse alpine environments.

For example, the native broad toothed rat depends on dense vegetation along watercourses. With feral horses eating out or trampling plants along streams, these delightful, rotund fur-balls may lose their homes, and hence be more exposed to the elements and predators.

Right now, feral horses are reducing the habitat for these animals, causing already threatened populations to become smaller and more fragmented. As these small populations blink into extinction we can expect widespread losses across the national park.

A colourful corroboree frog faces more destruction to breeding grounds.
Flickr/Australian Alps collection – Parks Australia, CC BY-ND

Corroboree frogs will now be under enormous pressure. We already know feral horses destroy the wetlands these iconic yellow-striped black frogs depend on for breeding. This destruction will likely now impact many more swamps, reducing breeding success and reducing options for reintroduction of this critically endangered frog.

Another species, the Stocky Galaxias, teeters on the brink of extinction. This small native fish now only lives in a 3km stretch of stream in Kosciuszko National Park. Feral horses trample the river banks and rip out vegetation that causes silt to accumulate in the stream.

This is disastrous for the fish, which breed beneath boulders in the stream. If silt fills up the gaps beneath boulders, there is no place for the fish to lay eggs.

The high numbers of feral horses in Kosciuszko mean this process of stream destruction will likely worsen, potentially hastening the demise of this species unique to Kosciuszko National Park.

New management plan needed

Hope for change now rests with the new feral horse management plan being developed by the recently established Kosciuszko National Park Wild Horse Community Advisory Panel and the Wild Horse Scientific Advisory Panel. The community panel has expressed interest in working with the scientific panel, and such collaboration will be essential for making progress.




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These committees will need to consider all options for resolving this human safety, animal welfare, and ecological crisis. Although trapping is crueller and many times more expensive than aerial culling, if the trapping effort is substantially ramped up across the park, it could potentially limit population growth and reduce horse numbers.

Aerial culling, despite being the most cost-effective and humane method to lower the horse population size and reduce impacts, is misrepresented by the pro-brumby lobby and sections of the media as cruel, and hence has been deemed unacceptable. These costs, and animal welfare and political trade-offs, must be carefully considered by the committees.

The scientific committee said the draft plan for action will be open for comment in February 2020 to meet NSW environment minister Matt Kean’s deadline for a final plan by May 1, 2020. This rapid timeframe is absolutely essential, as the increase of feral horses in the Alpine National Park will not abate any time soon without urgent and substantial control measures.The Conversation

Don Driscoll, Professor in Terrestrial Ecology, Deakin University; David M Watson, Professor in Ecology, Charles Sturt University, and Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University

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