Introduction

Much of our beloved wildlife is endemic to Australia’s unique land- and sea- scapes. Many species cannot survive anywhere else on Earth. Yet human activity compounded by climate change is fuelling an extinction crisis.

Nature underpins life on Earth; the air we breathe, the food we eat, the water we drink. The health of diverse ecosystems is interdependent on the climate, which is heating faster than ever before. Many precious species can’t keep up with this pace of change. 

Extreme heatwaves, bushfires and floods in Australia are devastating biodiversity and undermining conservation efforts. The lush, old-growth forests and rich, healthy oceans that have balanced the Earth’s carbon levels for millennia are now on the brink of collapse. Global warming and biodiversity loss are caught in a self-perpetuating cycle. Indeed, biodiversity conservation is climate change action. 

Relevant Sustainable Development Goals 

A vicious cycle

The Earth’s incredible natural carbon sinks — biodiverse ecosystems that absorb more carbon than they emit — draw down around 50 per cent of human-induced CO2 emissions. However, climate change is driving biodiversity loss to such an extent that these crucial ecosystems can no longer sequester the huge amounts of carbon they used to. This loss of biodiversity releases more CO2 into the atmosphere which, in turn, drives global warming that perpetuates extreme temperatures that decimate biodiversity. 

Australia is home to globally significant carbon sinks; however, they are approaching tipping points of collapse. Our land-based ecosystems accumulate some 150 million tonnes of CO2 each year on average — helping to offset national fossil fuel emissions by around one third. Our mangrove, seagrass and saltmarsh habitats hold 5 to 11 per cent of the world’s blue carbon storage. However, extreme weather events caused by climate change undermine these natural offsets. The 2019–20 Black Summer bushfires released 900 million tonnes of carbon into the air, causing mass dieback of mangroves in northern Australia and polluting the Murray River and Lake Hume with high loads of sediment and ash. With more frequent extreme disasters of this scale predicted as the planet heats, major carbon sinks will transform into carbon sources. The Earth’s carbon cycle is out of balance, with climate change and biodiversity loss trapped in a self-perpetuating cycle of destruction. 

Evolution can’t keep up

Extinctions across the world prove many species cannot cope with the rapid rate of climate change we are now experiencing. 

The waters off Australia’s south-east coast have warmed at almost four times the global average, with profound impact. Further north, 99 per cent of green turtle hatchlings in the Great Barrier Reef are now born female because the sand temperature where they lay their eggs is too hot for male eggs to incubate. At 34°C, the eggs won’t hatch at all. Green turtles are one of at least 9000 species that depend on the Great Barrier Reef for their survival, yet the reef itself is struggling to survive due to climate impacts and has now experienced its sixth mass bleaching. 

Interconnected food chains mean weather events in one ecosystem affect biodiversity in another. For example, prolonged drought in northern NSW and southern Queensland decimated bogong moth numbers in 2017 by stunting the grass on which their larvae feed. Further south in the Australian Alps of Victoria, the mountain pygmy possum now faces extinction because the bogong moth is its main food source. Climate change is already affecting nature’s ability to provide for the breadth of species that call our planet home.

Ecosystems pushed to the brink

Extreme weather events caused by global warming cause mass extinction at a local level, pushing ecosystems past tipping points and into collapse. Three billion native animals were killed or displaced by Australia’s 2019–20 Black Summer bushfires, making it the worst wildlife disaster in modern history. Eight million hectares of vegetation burned, including globally significant biodiversity hotspots such as the ancient Gondwanan rainforest; 116 plant species were completely extinguished. The megafires were so huge they polluted coastal habitats downstream — the first ever global record of bushfires impacting estuarine habitat quality.