In a statement published in the American scientific journal Bioscience, more than 15,000 scientists from 184 countries, assessing progress from 1992 to the present day, conclude that it will soon be "too late" to save the Earth.

The appeal is signed by exactly 15,364 researchers. In 1992, the Union of Concerned Scientists had gathered more than 1,700 scientists and launched the "World Scientists' Warning to Humanity", a document in which researchers argued that human impacts on the natural world would likely bring substantial damage to the planet, potentially irreversible in nature.

Since then, something has been done to try to reverse the trend, but not enough. The progress made in reducing the chemical compounds that cause the hole in the ozone layer, in increasing energy from renewable sources, and in the decline in the deforestation rate — which fell from 0.18% per year in 1992 to 0.08% today — has not been sufficient.

Since 1992, with the exception of the stabilisation of the ozone layer, humanity has failed to make sufficient progress in addressing environmental problems as a whole, and many of them are worsening by far. Particularly worrying is the current trajectory of potentially catastrophic climate change, due to the increasing volume of greenhouse gases produced by fossil fuels, deforestation and agriculture (in particular emissions related to the rearing of ruminants destined for slaughter).

Now, 25 years on, William J. Ripple, a researcher at Oregon State University, together with more than 15,000 scientists from 184 countries, have taken stock and updated the original document. From data drawn from government agencies, organisations and individual studies, it has become clear that the news is far from good. "Humanity is not taking the urgent steps needed to safeguard our imperilled biosphere," the authors state, noting that the vast majority of the threats previously described not only remain "alarming" but are in fact getting worse.

Climate change, human population growth and biodiversity loss

On what was until now the most important day of COP 23 in Bonn — the high-level segment — Angela Merkel called climate change the "central challenge for the fate of humanity." At the same time, however, she was careful to hedge on Germany's excessive dependence on coal, saying that the closure of power plants is "a social problem" that must be addressed "calmly."

For Emmanuel Macron, "the threshold of irreversibility has been crossed," and he explicitly cited the warning issued by the 15,000 scientists released on Monday. "The warnings are multiplying," the French president emphasised, recalling that the commitment made in Paris in 2015 was to limit the temperature rise to 1.5 degrees by 2100 relative to pre-industrial levels, whereas today the Earth is on a trajectory towards 3 degrees. "If we continue like this, it is as though we were tacitly and collectively accepting the disappearance of peoples represented here," amid rising sea levels, droughts, famines, conflicts, epidemics and refugees.

The appeal of more than 15,000 scientists united in renewing an alarm

The problems highlighted in 1992 have not been resolved, but have instead worsened. The underlying problem remains unchanged: the Earth's resources are finite and humanity is consuming them in an uncontrolled manner. Scientists, media influencers and ordinary citizens are not doing enough, the signatories of the document allege, adding:

Those who have signed this second warning are not raising a false alarm. Those who have done so recognise the evident signs that we are heading down an unsustainable path. We hope that our document will fuel broad public debate on the environment and the climate.
We are jeopardising our future by not reining in our intense but geographically and demographically uneven material consumption and by failing to perceive the rapid and ongoing growth of the human population as a key driver of many ecological and also social threats.

The active measures proposed by the scientists to protect the biosphere include:

adequately limiting population growth, re-examining the role of an economy rooted in growth, reducing greenhouse gases, incentivising renewable energies, protecting habitat, rebuilding ecosystems, reducing pollution, halting defaunation

As noted, not the entire picture is negative. Progress has been made in some areas, but these achievements are overshadowed by results pointing in the opposite direction. Over the past 25 years, the scientists note:

• The amount of fresh water available to the world's population has decreased by 26%
• The number of oceanic dead zones (areas where animal life does not spread due to pollution and low oxygen levels) has increased by 75%
• Around 120 million hectares of forests have been destroyed to make way for agricultural land
• Greenhouse gas emissions have increased by more than 60%
• The average land temperature has risen by 167%
• The human population has grown by 35 per cent
• The animal population (mammals, reptiles, amphibians, birds and fish) has declined by 29 per cent.

The point of no return is far closer than it was 25 years ago: it will soon be too late to steer away from the fatal trajectory. Some of the issues highlighted in the new appeal are also a priority for many companies, which are increasingly committed to pursuing production in line with sustainability criteria. Others fall outside the reach of the private sphere and require a sustained commitment from institutions at the global level. But individual end users should not feel excluded from the scientists' appeal, which calls for a personal awakening from everyone.

"Some people may not accept our evidence and may think it is simply alarmist. But an enormous number of scientists are analysing the data and studying the potential long-term consequences," Ripple concludes. "Those who have signed this second document are indeed not only raising an alarm, but recognise the evident signs that we human beings are embarking on a wholly unsustainable path. We hope that our document will spark broad public debate on both the environment and the global climate."

Thirteen recommendations then follow to avoid, in extremis, the worst. These include preserving forests, promoting a predominantly plant-based diet, reducing demographic growth, and accelerating the transition to renewable energies.