The emergency is not invisible. But that doesn't mean we can see it.

After decades of inaction and ineffective action on biodiversity decline, climate change, and pollution, civilisation stands on the precipice of a "ghastly future" it has gravely underestimated, an international team of scientific experts warns in an unnerving new study published this week.

"The scale of the threats to the biosphere and all its lifeforms – including humanity – is in fact so great that it is difficult to grasp for even well-informed experts," the researchers, led by global ecologist Corey Bradshaw from Flinders University in Australia, explain in their paper.

"The mainstream is having difficulty grasping the magnitude of this loss, despite the steady erosion of the fabric of human civilisation."

If the grandiose language seems almost hyperbolic, that's only because of the incredibly high stakes of what we're actually talking about here.

While the authors know fully well that their assessments will be denied, attacked, and ridiculed in many quarters, the knowledge doesn't obviate them – or the scientific community they represent – of the responsibility for sharing the news.

"Our message might not be popular, and indeed is frightening," the researchers write in a companion piece on The Conversation.

"But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face."

According to the team's research – a review of over 150 studies on different aspects of the worsening state of the natural world – the central problems we face are economic and political systems centred around unsustainable human consumption and population growth at the expense of all else.

The roots of biodiversity loss can be traced back some 11,000 years to the start of agriculture, but the problem has vastly accelerated in recent centuries due to ever-worsening pressures placed on natural ecosystems, to the extent that the reality of a sixth major extinction is now scientifically undeniable, the researchers write.

At the same time, the global human population keeps growing, having doubled since 1970, with estimates suggesting a peak population of nearly 10 billion by the end of the century.

In turn, this ever-expanding human footprint is expected to accelerate and worsen existing food insecurity, soil degradation, biodiversity decline, pollution, social inequality, and regional conflicts.

"This massive ecological overshoot is largely enabled by the increasing use of fossil fuels," the researchers write.

"These convenient fuels have allowed us to decouple human demand from biological regeneration: 85 percent of commercial energy, 65 percent of fibres, and most plastics are now produced from fossil fuels."

Despite all of this being considered established scientific knowledge, human life for the main part largely goes on as if it weren't, the researchers say.

"Stopping biodiversity loss is nowhere close to the top of any country's priorities, trailing far behind other concerns such as employment, healthcare, economic growth, or currency stability," the authors write.

"Humanity is running an ecological Ponzi scheme in which society robs nature and future generations to pay for boosting incomes in the short term. Even the World Economic Forum, which is captive of dangerous greenwashing propaganda, now recognises biodiversity loss as one of the top threats to the global economy."

Even climate change, which is a much more visible threat than biodiversity loss, appears to be too difficult for human societies to contend with, with ever-rising greenhouse gas concentrations, and continued failures by nations to effectively reduce their emissions or set effective climate targets.

Against the grim backdrop of such existential threats, electorates are increasingly embracing right-wing populist leaders with anti-environment agendas that only intensify the existing pressures, while perpetuating false paradigms that peg the 'environment' against the 'economy'.

In the long term, the authors say we are looking at a "ghastly future of mass extinction, declining health, and climate-disruption upheavals (including looming massive migrations) and resource conflicts", if we are unable to change the course of human society in a direction that prevent extinctions and restore ecosystems.

Despite the seeming fatalism of this alarming assessment, the researchers insist theirs is not a call to surrender, but rather a 'cold shower' humanity and its leaders seem to desperately need – a brutal reality check to snap people out of their sleepy, dangerous inertia.

"While there have been more recent calls for the scientific community in particular to be more vocal about their warnings to humanity, these have been insufficiently foreboding to match the scale of the crisis," the scientists conclude.

"It is therefore incumbent on experts in any discipline that deals with the future of the biosphere and human well-being to eschew reticence, avoid sugar-coating the overwhelming challenges ahead and 'tell it like it is'. Anything else is misleading at best, or negligent and potentially lethal for the human enterprise at worst."

The findings are reported in Frontiers in Conservation Science.