A new report has detailed the planet's frightening loss of life, with monitored wildlife populations plunging by an average of 69 per cent in less than 50 years.
The Living Planet report, produced every two years by the World Wide Fund for Nature, carries stark warnings for humanity unless the global haemorrhage can be stopped and reversed.
It cites "terrifying" figures on wildlife losses in roughly half a human lifetime, as the twin emergencies of climate change and biodiversity loss collide.
"(There's been) an average 69 per cent decline in the relative abundance of monitored wildlife populations around the world between 1970 and 2018," the report says.
The findings are based on the Living Planet Index, provided by the Zoological Society of London and informed by data on almost 32,000 monitored populations across 5230 species of mammals, birds, reptiles, amphibians and fish.
The destruction and fragmentation of natural habitats on the land, in freshwater and in the sea remains the biggest current threat to nature.
But the report warns climate change will likely overtake that in coming decades if the world fails to limit warming to 1.5C.
The situation is bad in all parts of the world but some are faring far worse than others.
The greatest decline is in Latin America and the Caribbean, where monitored wildlife populations have seen an average drop of 94 per cent since 1970.
In the Asia Pacific region, including Australia, monitored populations are down 55 per cent.
A prominent example is the Australian sea lion, which isn't found anywhere else.
The number of pups born each breeding cycle has plunged by an estimated 64 per cent in 42 years, largely due to historical hunting and gillnet fishing, entanglement in other marine debris, pollution and disease.
The species is now only found off South Australia and the southern half of Western Australia. Of 80 breeding sites, half produce fewer than 15 pups per breeding cycle and less than 10,000 sea lions are thought to be left.
Marine biologist Simon Goldsworthy, from the South Australian Research and Development Institute, is hopeful the species can claw its way back after fishing rules were changed to stop so many drowning in gillnets and lobster pots.
But the sea lion is just one of the Australian species in trouble.
"The state of our environment is deeply concerning. I think we all worry about impacts from climate, population growth, our demand on natural resources.
"Where's it going to end? Where does that leave room for populations of species we share the planet with? It's a pretty bleak situation."
WWF-Australia chief executive Dermot O'Gorman is among those calling for a global agreement to reverse biodiversity loss, similar to the Paris climate pact.
"For Australia and the world, simply halting biodiversity loss is not enough; we need a nature-positive goal which means reversing the loss of nature."
He hopes the United Nations biodiversity summit in December will see nations step up and commit to a global pact to reverse the fortunes of the world's wildlife.
"We don't have much time. If we were off to the doctor this would be a code red for both the planet and humanity. We need urgent action."
The recent State of the Environment report found Australia's environment is in poor condition and deteriorating, with 19 ecosystems showing signs of collapse or near collapse.
