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March 2, 2021

'Existential threat to our survival': see the 19 Australian ecosystems already collapsing

A comprehensive evaluation of the environmental state of play in Australia shows major and iconic ecosystems are collapsing

In 1992, 1,700 scientists that human beings and the natural world were 鈥渙n a collision course鈥�. Seventeen years later, scientists described within which humans and other life could have a 鈥渟afe space to operate鈥�. These are environmental thresholds, such as the amount of carbon dioxide in the atmosphere and changes in land use.

Crossing such boundaries was considered a risk that would cause environmental changes so profound, they genuinely posed an .

This grave reality is what our major research paper, , confronts.

In what may be the most comprehensive evaluation of the environmental state of play in Australia, we show major and iconic ecosystems are collapsing across the continent and into Antarctica. These systems sustain life, and evidence of their demise shows we鈥檙e exceeding planetary boundaries.

We found 19 Australian ecosystems met our criteria to be classified as 鈥渃ollapsing鈥�. This includes the arid interior, and of northern Australia, the , , southern Australia鈥檚 and forests, tundra on Macquarie Island, and .

We define collapse as the state where ecosystems have changed in a substantial, negative way from their original state 鈥� such as species or habitat loss, or reduced vegetation or coral cover 鈥� and are unlikely to recover.

 

The good and bad news

Ecosystems consist of living and non-living components, and their interactions. They work like a super-complex engine: when some components are removed or stop working, knock-on consequences can lead to system failure.

Our study is based on measured data and observations, not modelling or predictions for the future. Encouragingly, not all ecosystems we examined have collapsed across their entire range. We still have, for instance, some intact reefs on the Great Barrier Reef, especially in deeper waters. And northern Australia has some of the most intact and least-modified stretches of savanna woodlands on Earth.

Still, collapses are happening, including in regions critical for growing food. This includes the , which covers around 14% of Australia鈥檚 landmass. Its rivers and other freshwater systems support more than production.

The effects of floods, fires, heatwaves and storms do not stop at farm gates; they鈥檙e felt equally in agricultural areas and natural ecosystems. We shouldn鈥檛 forget how towns ran out of during the recent drought.

Drinking water is also at risk when ecosystems collapse in our water catchments. In Victoria, for example, the degradation of giant greatly reduces the amount of water flowing through the Thompson catchment, threatening nearly five million people鈥檚 drinking water in Melbourne.

This is a dire wake-up call 鈥� not just a warning. Put bluntly, current changes across the continent, and their potential outcomes, pose an existential threat to our survival, and other life we share environments with.

 

In investigating patterns of collapse, we found most ecosystems experience multiple, concurrent pressures from both global climate change and regional human impacts (such as land clearing). Pressures are often .

Take the last 11 years in Western Australia as an example.

In the summer of 2010 and 2011, a spanning more than 300,000 square kilometres ravaged both marine and land ecosystems. The extreme heat devastated forests and woodlands, kelp forests, seagrass meadows and coral reefs. This catastrophe was followed by two cyclones.

A record-breaking, marine heatwave in late 2019 dealt a further blow. And another marine heatwave is predicted for .

These 19 ecosystems are collapsing: read about each

 

What to do about it?

Our brains trust comprises 38 experts from 21 universities, CSIRO and the federal Department of Agriculture Water and Environment. Beyond quantifying and reporting more doom and gloom, we asked the question: what can be done?

We devised a simple but tractable scheme called the 3As:

• Awareness of what is important

• Anticipation of what is coming down the line

• Action to stop the pressures or deal with impacts.

In our paper, we identify positive actions to help protect or restore ecosystems. Many are already happening. In some cases, ecosystems might be better left to recover by themselves, such as coral after a cyclone.

In other cases, active human intervention will be required 鈥� for example, placing artificial nesting boxes for Carnaby鈥檚 black cockatoos in areas where old trees have been .

 

鈥淔uture-ready鈥� actions are also vital. This includes reinstating , which have and can help minimise the risk and strength of bushfires.

It might also include replanting banks along the Murray River with species better suited to .

Some actions may be small and localised, but have substantial positive benefits.

For example, billions of migrating Bogong moths, the main summer food for critically endangered mountain pygmy possums, have not arrived in their typical numbers in Australian alpine regions in recent years. This was further exacerbated by the fires. Brilliantly, anticipated this pressure and developed supplementary food 鈥� .

Other more challenging, global or large-scale actions must address the , such as of environmental resources.

We must rapidly reduce greenhouse gas emissions to net-zero, remove or suppress invasive species such as and , and stop widespread and other forms of habitat destruction.

Our lives depend on it

The multiple ecosystem collapses we have documented in Australia are a harbinger for .

The simplicity of the 3As is to show people can do something positive, either at the local level of a landcare group, or at the level of government departments and conservation agencies.

Our lives and those of our , as well as our , societies and , depend on it.

We simply cannot afford any further delay.

, Principal Research Scientist, ; , Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, ; , Professor, Department of Biological Sciences, , and , Professor and Chair, Environment and Human Health,

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