1,575 scientists signed the World Scientists' Warning to Humanity in 1992, including more than half of all living scientists awarded the Nobel Prize. More and more add their names to this momentous document. We must all broadcast this alarm. The imminent ecological collapse facing the natural world cries out for immediate global action. Only concerted cooperation of world governments offers hope of reversing this ominous trend. The United States alone has the means and stature to become the leader among nations for humanity's rescue. Vice President Al Gore's book, Earth in the Balance, offers practical solutions that would not only reverse these trends, but eliminate poverty and generate the greatest economic prosperity humanity ever experienced. Henry Kendall, Nobel laureate, Physics, and Chairman of the Union of Concerned Scientists (UCS), organized the magisterial work that produced this warning. No other issue today is more important than this one because without restoring balance and insuring survival of life on this planet, all other issues cease to exist.

World Scientists' Warning to Humanity

Human beings and the natural world are on a collision course. Human activities inflict harsh and often irreversible damage to the environment and on critical resources. If not checked, 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. Fundamental changes are urgent if we are to avoid the collision our present course will bring about.

The Environment
The environment is suffering critical stress:

The Atmosphere
Stratospheric ozone depletion threatens us with enhanced ultraviolet radiation at the earth's surface, which can be damaging or lethal to many life forms. Air pollution near ground level, and acid precipitation, are already causing widespread injury to humans, forests, and crops.

Water Resources
Heedless exploitation of depletable groundwater supplies endangers food production and other essential human systems. Heavy demands on the world's surface waters have resulted in serious shortages in some 80 countries, containing 40 percent of the world's population. Pollution of rivers, lakes, and groundwater further limits the supply.

Destructive pressure on the oceans is severe, particularly in the coastal regions, which produce most of the world's food fish. The total marine catch is now at or above the estimated maximum sustainable yield. Some fisheries have already show signs of collapse. Rivers carrying heavy burdens of eroded soil into the seas also carry industrial, municipal, agricultural, and livestock waste--some of it toxic.

Loss of soil productivity, which is causing extensive land abandonment, is a widespread by-product of current practices in agriculture and animal husbandry. Since 1945, 11 percent of the earth's vegetated surface has been degraded--an area larger than India and China combined--and per capita food production in many parts of the world is decreasing.

Tropical rain forests, as well as tropical and temperate dry forests, are being destroyed rapidly. At present rates, some critical forest types will be gone in a few years, and most of the tropical rain forest will be gone before the end of the next century. With them will go large numbers of plant and animal species.

Living Species
The irreversible loss of species, which by 2100 may reach one-third of all species now living, is especially serious. We are losing the potential they hold for providing medicinal and other benefits, and the contribution that genetic diversity of life forms gives to the robustness of the world's biological systems and to the astonishing beauty of the earth itself.

Much of this damage is irreversible on a scale of centuries or permanent. Other processes appear to pose additional threats. Increasing levels of gases on the atmosphere from human activities, including carbon dioxide released from fossil fuel burning and from deforestation, may alter climate on a global scale. Predictions of global warming are still uncertain--with projected effects ranging from tolerable to very severe--but the potential risks are very great.

Our massive tampering with the world's interdependent web of life--coupled with the environmental damage inflicted by deforestation, species loss, and climate change--could trigger widespread adverse effects, including unpredictable collapses of critical biological systems whose interactions and dynamics we only imperfectly understand.

Uncertainty over the extent of these effects cannot excuse complacency or delay in facing the threats.

The earth is finite. Its ability to absorb wastes and destructive effluent is finite. Its ability to provide food and energy is finite. Its ability to provide for growing numbers of people is finite. And we are fast approaching many of the earth's limits. Current economic practices that damage the environment, in both developed and underdeveloped nations, cannot be continued without the risk that vital global systems will be damaged beyond repair.

Pressures resulting from unrestrained population growth put demands on the natural world that can overwhelm any efforts to achieve a sustainable future. If we are to halt the destruction of our environment, we must accept limits to that growth. A World Bank estimate indicates that world population will not stabilize at less than 12.4 billion, while the United Nations concludes that the eventual total could reach 14 billion, a near tripling of today's 5.4 billion. But, even at this moment, one person in five lives in absolute poverty without enough to eat, and one in ten suffers serious malnutrition.

No more than one or a few decades remain before the chance to avert the threats we now confront will be lost and the prospect of humanity immeasurably diminished.

We the undersigned, senior members of the world's scientific community, hereby warn all humanity of what lies ahead. A great change in our stewardship of the earth and the life on it is required if vast human misery is to be avoided and our global home on this planet is not to be irretrievably mutilated.

What We Must Do
Five inextricably linked areas must be addressed simultaneously:

1. We must bring environmentally damaging activities under control to restore and protect the integrity of the earth's systems we depend on. We must, for example, move away from fossil fuels to more benign, inexhaustible energy sources to cut greenhouse gas emissions and the pollution of our air and water. Priority must be given to the development of energy sources matched to Third World needs--small-scale and relatively easy to implement.

We must halt deforestation, injury to and loss of agricultural land, and the loss of terrestrial and marine plant and animal species.

2. We must manage resources crucial to human welfare more effectively. We must give high priority to efficient use of energy, water, and other materials, including expansion of conservation and recycling.

3. We must stabilize population. This will be possible only if all nations recognize that it requires improved social and economic conditions, and the adoption of effective, voluntary family planning.

4. We must reduce and eventually eliminate poverty. 

5. We must ensure sexual equalityl, and guarantee women control over their own reproductive decisions.

The developed nations are the largest polluters in the world today. They must greatly reduce their overconsumption if we are to reduce pressures on resources and the global environment. The developed nations have the obligation to provide aid and support to developing nations, because only the developed nations have the financial resources and the technical skills for these tasks.

Action on this recognition is not altruism, but enlightened self-interest: whether industrialized or not, we all have but one lifeboat. No nation can escape from injury when global biological systems are damaged. No nation can escape from conflicts over increasingly scarce resources. In addition, environmental and economic instabilities will cause mass migrations with incalculable consequences for developed and undeveloped nations alike.

Developing nations must realize that environmental damage is one of the gravest threats they face and that attempts to blunt it will be overwhelmed if their populations go unchecked. The greatest peril is to become trapped in spirals of environmental decline, poverty, and unrest, leading to social, economic, and environmental collapse.

Success in this global endeavor will require a great reduction in violence and war. Resources now devoted to the preparation and conduct of war--amounting to over $1 trillion annually--will be badly needed in the new tasks and should be diverted to the new challenges.

A new ethic is required--a new attitude toward discharging our responsibility for caring for ourselves and for the earth. We must recognize the earth's limited capacity to provide for us. We must recognize its fragility. We must no longer allow it to be ravaged. This ethic must motivate a great movement, convincing reluctant leaders and reluctant governments and reluctant peoples themselves to effect the needed changes. The scientists issuing this warning hope that our message will reach and affect people everywhere. We need the help of many.

We require the help of the world community of scientists--natural, social, economic, political;

We require the help of the world's business and industrial leaders;

We require the help of the world's religious leaders; and

We require the help of the world's peoples.

We call on all to join us in this task.


The following is an abridged list of the signers:
Walter Alvarez, Geologist, National Academy of Scientists; USA
Philip Anderson, Nobel laureate, Physics; USA
Christian Anfinsen, Nobel laureate, Chemistry; USA
Werner Arber, Nobel laureate, Medicine; Switzerland
Michael Atiyal, Mathematician, President, Royal Society; Great Britain
Mary Ellen Avery, Pediatrician, National Medal of Science; USA
Julius Axelrod, Nobel laureate, Medicine; USA
Howard Bachrach, Biochemist, National Medal of Science; USA
John Backus, Computer Scientist, National Medal of Science; USA
David Baltimore, Nobel laureate, Medicine; USA
David Bates, Physicist, Royal Irish Academy; Ireland
George Bednorz, Nobel laureate, Physics; Switzerland
Baruj Benacerraf, Nobel laureate, Medicine; USA
Sune Bergstrom, Nobel laureate, Medicine; Sweden
Hans Bethe, Nobel laureate, Physics; USA
Konrad Bloch, Nobel laureate, Medicine; USA
Nicholaas Bloembergen, Nobel laureate, Physics; USA
Bert Bolin, Meterologist, Tyler Prize, Sweden
Norman Borlaug, Agricultural Scientist, Nobel laureate, Peace; USA & Mexico
E. Margaret Burbidge, Astronomer, National Medal of Science; USA
Adolph Butenandt, Nobel laureate, Chemistry, Former President, Max Planck Institute; Germany
Ennio Candotti, Physicist, President, Brazilian Society for the Advancement of Science; Brazil
Georges Charpak, Nobel laureate, Physics; France
Paul Crutzen, Chemist, Tyler Prize; Germany
Jean Dausset, Nobel laureate, Medicine; France
Margaret Davis, Ecologist, National Academy of Sciences; USA
Gerard Debreu, Nobel laureate, Economics; USA
Paul-Yves Denis, Geographer, Academy of Sciences; Canada
Thomas Eisner, Biologist, Tyler Prize; USA
Mohammed T. El-Ashry, Environmental scientist, Third World Academy; Egypt & USA
Mahdi Elmandjra, Economist; Vice President, African Academy of Sciences; Morocco
Richard Ernst, Nobel laureate, Chemistry; Switzerland
Dagfinn Follesdal, President, Norwegian Academy of Science; Norway
Otto Frankel, Geneticist, Australian Academy of Sciences; Australia
Konstantin V. Frolov, Engineer, Vice President, Russian Academy of Sciences; Russia
Kenichi Fukui, Nobel laureate, Chemistry; Japan
Robert Gallo, Research scientist, Lasker Award; USA
Murray Gell-Mann, Nobel laureate, Physics; USA
Donald Glaser, Nobel laureate, Physics; USA
Sheldon Glashow, Nobel laureate, Physics; USA
Marvin Goldberger, Physicist, Former President, California Institute of Technology; USA
Stephen Jay Gould, Paleontologist, Author, Harvard University; USA
Stephen Hawking, Mathematician, Wolf Prize in Physics; Great Britain
Dudley Herschback, Nobel Prize, Chemistry; USA
Dorothy Crowfoot Hodgkin, Nobel laureate, Chemistry; Great Britain
Roald Hoffman, Nobel laureate, Chemistry; USA
Nick Holonyak, Electrical Engineer, National Medal of Science; USA
Sarah Hrdy, Anthropologist, National Academy of Sciences; USA
Kun Huang, Physicist, Chinese Academy of Sciences; China
Hiroshi Inose, Electrical Engineer, Vice President, Engineering Academy; Japan
Francois Jacob, Nobel laureate, Medicine; France
Carl-Olof Jacobson, Zoologist, Secretary-General, Royal Academy of Sciences; Sweden
Daniel Janzen, Biologist, Crafoord Prize; USA
Harold Johnston, Chemist, Tyler Prize; USA
Robert Kates, Geographer, National Medal of Science; USA
Frederick I.B. Kayanja, Vice-Chancellor, Mbarara University, Third World Academy; Uganda
Henry Kendall, Nobel laureate, Physics, Chairman, Union of Concerned Scientists; USA
Gurdev Khush, Agronomist, International Rice Institute, Indian National Science Academy; India & Philippines
Klaus von Klitzing, Nobel laureate, Physics; Germany
Aaron Klug, Nobel laureate, Chemistry; Great Britain
E.F. Knipling, Agricultural Researcher, National Medal of Science; USA
Walter Kohn, Physicist, National Medal of Science; USA
Torvard Laurent, Physiological Chemist, President Royal Academy of Sciences; Sweden
Leon Lederman, Nobel laureate, Physics, Chairman, American Association for the Advancement of Science; USA
Wassily Leontief, Nobel laureate, Economics; USA
Luna Leopold, Geologist, National Medal of Science; USA
Rita Levi-Montalcini, Nobel laureate, Medicine; USA & Italy
William Lipscomb, Nobel laureate, Physics; USA
Jane Lubchenco, Zoologist, President-Elect, Ecological Society of America; USA
Lynn Margulis, Biologist, National Academy of Sciences; USA
George Martine, Institute for Study of Society, Population & Nature; Brazil
Ernst Mayr, Zoologist, National Medal of Science; USA
Digby McLaren, Past President, Royal Society of Canada; Canada
James Meade, Nobel laureate, Economics; Great Britain
Jereold Meinwald, Chemistry, Tyler Prize; USA
M.G.K. Menon, Physicist, President, International Council of Scientific Unions; India
Gennady Mesiatz, Physicist, Vice President, Russian Academy of Sciences; Russia
César Milstein, Nobel laureate, Medicine; Argentina & Great Britain
Franco Modigliani, Nobel laureate, Economics; USA
Walter Munk, Geophysicist, National Medal of Science; USA
Lawrence Mysak, Meteorologist, Vice President, Academy of Science, Royal Society of Canada; Canada
James Neel, Geneticist, National Medal of Science; USA
Louis Néel, Nobel laureate, Physics; France
Howard Odum, Ecologist, Crafoord Prize; USA
Yuri Ossipyan, Physicist, Vice President, Russian Academy of Sciences, Russia
Autar Singh Paintal, Physiologist; Former President, Indian National Science Academy; India
Mary Lou Pardue, Biologist, National Academy of Sciences; USA
Linus Pauling, Nobel laureate, Chemistry & Peace; USA
Roger Penrose, Mathematician, Wolf Prize in Physics; Great Britain
John Polanyi, Nobel laureate, Chemistry; Canada
George Porter, Noble laureate, Chemistry; Great Britain
Ilya Prigogine, Nobel laureate, Chemistry; Belgium
Edward Purcell, Nobel laureate, Physics; USA
G.N. Ramachandran, Mathematician, Institute of Science; India
Peter Raven, Director, Missouri Botanical Garden, National Academy of Sciences; USA
Tadeus Reichstein, Nobel laureate, Medicine; Switzerland
Gustavo Rivas Mijares, Engineer, Former President, Academy of Sciences; Venezuela
Wendell Roelofs, Entomologist, National Medal of Science; USA
Miriam Rothschild, Biologist, Royal Society; Great Britain
Sherwood Rowland, Chemist, Past President, American Association for the Advancement of Science; USA
Carlo Rubbia, Nobel laureate, Physics; Italy & Switzerland
Albert Sabin, Virologist, National Medal of Science; USA
Carl Sagan; Astrophysicist & Author; USA
Roald Sagdeev, Physicist, Russian & Pontifical Academies; Russia & USA
Abdus Salam, Nobel laureate, Physics; President, Third World Academy of Sciences; Pakistan & Italy
José Sarukhan, Biologist, Third World Academy; México
Richard Schultes, Botanist, Tyler Prize; USA
Glenn Seaborg, Nobel laureate, Physics; USA
Roger Sperry, Nobel laureate, Medicine; USA
Ledyard Stebbins, Geneticist, National Medal of Science; USA
Janos Szentgothai, Former President, Hungarian Academy of Sciences; Hungary
Jan Tinbergen, Nobel laureate, Economics; Netherlands
James Tobin, Nobel laureate, Economics; USA
Susumu Tonegawa, Nobel laureate, Medicine; Japan & USA
James Van Allen, Physicist, Crafoord Prize; USA
Harold Varmus, Nobel laureate, Medicine; USA
George Wald, Nobel laureate, Medicine; USA
Gerald Wasserburg, Geophysicist, Crafoord Prize; USA
James Watson, Nobel laureate, Medicine; USA
Victor Weisskopf, Wolf Prize in Physics; USA
Fred Whipple, Astronomer, National Academy of Sciences; USA
Torsten Wiesel, Nobel laureate, Medicine; USA
Geoffrey Wilkinson, Nobel laureate, Chemistry; Great Britain
Edward O. Wilson, Biologist, Crafoord Prize; USA
Solly Zuckerman, Zoologist, Royal Society; Great Britain

For information regarding additional signatories, please contact Union of Concerned Scientists, 2 Brattle Square, Cambridge MA 02238-9105, (617) 547-5552.