In late 1992, 1,700 scientists from around the world issued a dire “warning to humanity.” They said humans had pushed Earth’s ecosystems to their breaking point and were well on the way to ruining the planet. The letter listed environmental impacts like they were biblical plagues — stratospheric ozone depletion, air and water pollution, the collapse of fisheries and loss of soil productivity, deforestation, species loss and catastrophic global climate change caused by the burning of fossil fuels.
“If not checked,” wrote the scientists, led by particle physicist and Union of Concerned Scientists co-founder Henry Kendall, “many of our current practices put at serious risk the future that we wish for human society and the plant and animal kingdoms, and may so alter the living world that it will be unable to sustain life in the manner that we know.”
But things were only going to get worse.
To mark the letter’s 25th anniversary, researchers have issued a bracing follow-up. In a communique published Monday in the journal BioScience, more than 15,000 scientists from 184 countries assess the world’s latest responses to various environmental threats. Once again, they find us sorely wanting.
“Humanity has failed to make sufficient progress in generally solving these foreseen environmental challenges, and alarmingly, most of them are getting far worse,” they write.
This letter, spearheaded by Oregon State University ecologist William Ripple, serves as a “second notice,” the authors say: “Soon it will be too late to shift course away from our failing trajectory.”
Global climate change sits atop the new letter’s list of planetary threats. Global average temperatures have risen by more than half a degree Celsius since 1992, and annual carbon dioxide emissions have increased by 62 percent.
But it’s far from the only problem people face. Access to fresh water has declined, as has the amount of forestland and the number of wild-caught fish (a marker of the health of global fisheries). The number of ocean dead zones has increased. The human population grew by a whopping 2 billion, while the populations of all other mammals, reptiles, amphibians and fish have declined by nearly 30 percent.
The lone bright spot exists way up in the stratosphere, where the hole in the planet’s protective ozone layer has shrunk to its smallest size since 1988. Scientists credit that progress to the phasing out of chlorofluorocarbons — chemicals once used in refrigerators, air conditioners and aerosol cans that trigger reactions in the atmosphere to break down ozone.
“The rapid global decline in ozone depleting substances shows that we can make positive change when we act decisively,” the letter says.
The authors offer 13 suggestions for reining in our impact on the planet, including establishing nature reserves, reducing food waste, developing green technologies and establishing economic incentives to shift patterns of consumption.
To this end, Ripple and his colleagues have formed a new organization, the Alliance of World Scientists, aimed at providing a science-based perspective on issues affecting the well-being of people and the planet.
“Scientists are in the business of analyzing data and looking at the long-term consequences,” Ripple said in a release. “Those who signed this second warning aren’t just raising a false alarm. They are acknowledging the obvious signs that we are heading down an unsustainable path. We are hoping that our paper will ignite a widespread public debate about the global environment and climate.”
Examples of steps humanity can take to transition to sustainability include the following:
- prioritizing the enactment of connected well-funded and well-managed reserves for a significant proportion of the world’s terrestrial, marine, freshwater, and aerial habitats;
- maintaining nature’s ecosystem services by halting the conversion of forests, grasslands, and other native habitats;
- restoring native plant communities at large scales, particularly forest landscapes;
- rewilding regions with native species, especially apex predators, to restore ecological processes and dynamics;
- developing and adopting adequate policy instruments to remedy defaunation, the poaching crisis, and the exploitation and trade of threatened species;
- reducing food waste through education and better infrastructure;
- promoting dietary shifts towards mostly plant-based foods;
- further reducing fertility rates by ensuring that women and men have access to education and voluntary family-planning services, especially where such resources are still lacking;
- increasing outdoor nature education for children, as well as the overall engagement of society in the appreciation of nature;
- divesting of monetary investments and purchases to encourage positive environmental change;
- devising and promoting new green technologies and massively adopting renewable energy sources while phasing out subsidies to energy production through fossil fuels;
- revising our economy to reduce wealth inequality and ensure that prices, taxation, and incentive systems take into account the real costs which consumption patterns impose on our environment; and
- estimating a scientifically defensible, sustainable human population size for the long term while rallying nations and leaders to support that vital goal.