In 1992, the Union of Concerned Scientists, along with more than 1,700 signatories, issued the “World Scientists’ Warning to Humanity,” in which they argued that human impacts on the natural world were likely to lead to “vast human misery” and a planet that was “irretrievably mutilated.”
On the 25th anniversary of the landmark declaration, William J. Ripple, a distinguished professor of ecology at Oregon State University, his colleagues, and over 15,000 signatories from 184 countries revisit the original warning in what they deem “A Second Notice.” Using time-series data, the authors evaluate human responses to the threats identified in 1992. With the exception of a stabilized stratospheric ozone layer, the news is not good. “Humanity is not taking the urgent steps needed to safeguard our imperiled biosphere,” report the authors. They note that the overwhelming majority of the previously outlined threats remain and “alarmingly, most of them are getting far worse.”
Ripple is best known for his research on terrestrial trophic cascades, particularly the role of the gray wolf in North America as an apex predator and a keystone species that shapes food webs and landscape structures via “top-down” pressures. One of his co-authors is Mauro Galetti, a Brazilian ecologist and conservation biologist. His expertise is in the ecological and evolutionary consequences of defaunation — the loss of animals from ecological communities. A paper he published in 2013 was titled “Functional extinction of birds drives rapid evolutionary changes in seed size.”
The signatories include at least 69 ornithologists or other scientists who primarily study birds. They include Tom Cade, founder of the Peregrine Fund, avian ecologist Jeff Hoover of the Illinois Natural History Survey, Mercedes S. Foster, an emeritus research zoologist in the Smithsonian Institution’s Division of Birds, and several researchers at the Max Planck Institute for Ornithology in Germany.
Other signatories are Jane Goodall, Harvard’s Edward O. Wilson, and former NASA scientist James Hansen. The paper has 15,372 signatories in total, from a range of scientific disciplines. It is thought to be the largest-ever formal support by scientists for a journal article.
Not all of the news is bleak. Ripple and his colleagues note that the “rapid global decline in ozone-depleting substances shows that we can make positive change when we act decisively.” To build on this success, the authors outline 13 areas in which reined-in human behaviors may be able to move the Earth’s systems toward sustainability. They include:
- 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; and
- Increasing outdoor nature education for children, as well as the overall engagement of society in the appreciation of nature.
The failure to heed this second notice, say the authors, would produce dire consequences, with catastrophic biodiversity loss and widespread misery for humans. The authors include a cautionary note: “Soon it will be too late to shift course away from our failing trajectory, and time is running out. We must recognize, in our day-to-day lives and in our governing institutions, that Earth with all its life is our only home.” But they also close with an optimistic message about working together on these environmental challenges: “We can make great progress for the sake of humanity and the planet on which we depend.”