Martin Rees OUR FINAL HOUR A Scientist's Warning: How Terror, Error, and Environmental Disaster Threaten Humankind's Future in This Century— On Earth and Beyond International Acclaim for Martin Rees's OUR FINAL HOUR "[Rees's] cautionary tale comes as a useful counterbalance to some of the overly optimistic books recently penned by scientists . Our Final Hour neither worships nor condemns modern science, but it does offer a clear, concise account of what may be our most urgent concerns in the 21st century." —The Globe and Mail (Toronto) "Doomsday books have appeared for centuries. But Rees' book is unique, and not only because of his fame as a Cambridge University professor who is not prone to making scary public statements." —San Francisco Chronicle "One of the most provocative and unsettling books I have read for many years . That a scientist so distinguished as Rees should air these fierce anxieties is a sign that something is amiss." —J. G. Ballard, The Daily Mail (London) "Rees invites us to also consider developments that many of us probably never thought about, including: Could environmental degradation lead to a "war for water"? Could machines-designed plants crowd natural plants out of the ecosystem? These ideas may inspire skepticism, but within Rees' logic, they seem far from impossible. But Rees does not simply outline his theories. Throughout, he repeatedly implies something else: We can do something to help." ________________ Associated Press OTHER BOOKS BY MART.N REES INCLUDE Graves Fatal Attraction: Black Holes in the Umverse with Mitchell Begelman Before the Beginning: Our Universe and Others Just Six Numbers: The Deep Forces That Shape the Universe Our Cosmic Habitat BASIC B BOOKS A Member of the Perseus Books Group New York Copyright © 2003 by Martin Rees Published by Basic Books, A Member of the Perseus Books Group Hardback first published in 2003 by Basic Books Paperback first published in 2004 by Basic Books All rights reserved. Printed in the United States of America. No part of this book may be reproduced in any manner whatsoever without written permission except in the case of brief quotations embodied in critical articles and reviews. For information, address Basic Books, 387 Park Avenue South, New York, NY 10016 Books published by Basic Books are available at special discounts for bulk purchases in the United States by corporations, institutions, and other organizations. For more information, please contact the Special Markets Department at the Perseus Books Group, 11 Cambridge Center, Cambridge, MA 02142, or call (617) 252-5298, (800) 255-1514 or e-mail [email protected]. Library of Congress Cataloging-in-Publication Data Rees, Martin J., 1942- Our final hour: A scientist's warning: How terror, error, and environmental disaster threaten humankind's future in this century— on Earth and beyond / Martin Rees. p. cm. Includes bibliographical references and index. ISBN 0-465-0682-6 (he); ISBN 0-465-06863-4 (pbk) 1. Twenty-first century—Forecasts. 2. Disasters—Forecasts. 3. End of the world. 1. Title. CB161.R38 2003 3O3.49'oo'o5—dc21 2003000301 Design by Jane Raese Text set in 11 point Janson 04 05 06 / 10 9 8 7 6 5 4 3 2 1 CONTENTS PROLOGUE ............................................................................................................................................................................. 7 2. TECHNOLOGY SHOCK ................................................................................................................................................... 15 A Human or Posthuman Future? ............................................................................................................................................. 25 3. THE DOOMSDAY CLOCK .............................................................................................................................................. 33 4. POST-2000 THREATS Terror and Error .......................................................................................................................... 49 5. PERPETRATORS AND PALLIATIVES .......................................................................................................................... 69 6. SLOWING SCIENCE DOWN? ......................................................................................................................................... 79 7 BASELINE NATURAL HAZARDS .................................................................................................................................. 95 Asteroid Impacts ..................................................................................................................................................................... 95 A Low Risk, but Not Negligible ............................................................................................................................................. 98 Reducing the Risk? ............................................................................................................................................................... 100 8. HUMAN THREATS TO EARTH .................................................................................................................................... 104 9. EXTREME RISKS ........................................................................................................................................................... 116 Our "Final" Experiment? ...................................................................................................................................................... 120 11.THE END OF SCIENCE? ............................................................................................................................................... 141 12. DOES OUR FATE HAVE COSMIC SIGNIFICANCE? ............................................................................................... 156 13. BEYOND EARTH ......................................................................................................................................................... 168 NOTES ................................................................................................................................................................................. 185 PREFACE SCIENCE IS ADVANCING FASTER THAN EVER, and on a broader front: bio-, cyber- and nanotechnology all offer exhilarating prospects; so does the exploration of space. But there is a dark side: new science can have unintended consequences; it empowers individuals to perpetrate acts of megaterror; even innocent errors could be catastrophic. The "downside" from twenty-first century technology could be graver and more intractable than the threat of nuclear devastation that we have faced for decades. And human-induced pressures on the global environment may engender higher risks than the age-old hazards of earthquakes, eruptions, and asteroid impacts. This book, though short, ranges widely. Separate chapters can be read almost independently: they deal with the arms race, novel technologies, environmental crises, the scope and limits of scientific invention, and prospects for life beyond the Earth. I've benefited from discussions with many specialists; some of them will, however, find my cursory presentation differently slanted from their personal assessment. But these are controversial themes, as indeed are all "scenarios" for the long-term future. If nothing else, I hope to stimulate discussion on how to guard (as far as is feasible) against the worst risks, while deploying new knowledge optimally for human benefit. Scientists and technologists have special obligations. But this perspective should strengthen everyone's concern, in our interlinked world, to focus public policies on communities who feel aggrieved or are most vulnerable. I thank John Brockman for encouraging me to write the book. I'm grateful to him and to Elizabeth Maguire for being so patient, and to Christine Marra and her colleagues for their efficient and expeditious efforts to get it into print. OUR FINAL HOUR PROLOGUE THE TWENTIETH CENTURY BROUGHT US THE BOMB, and the nuclear threat will never leave us; the short-term threat from terrorism is high on the public and political agenda; inequalities in wealth and welfare get ever wider. My primary aim is not to add to the burgeoning literature on these challenging themes, but to focus on twenty-first century hazards, currently less familiar, that could threaten humanity and the global environment still more. Some of these new threats are already upon us; others are still conjectural. Populations could be wiped out by lethal "engineered" airborne viruses; human character may be changed by new techniques far more targeted and effective than the nostrums and drugs familiar today; we may even one day be threatened by rogue nanomachines that replicate catastrophically, or by superintelligent computers. Other novel risks cannot be completely excluded. Experiments that crash atoms together with immense force could start a chain reaction that erodes everything on Earth; the experiments could even tear the fabric of space itself, an ultimate "Doomsday" catastrophe whose fallout spreads at the speed of light to engulf the entire universe. These latter scenarios may be exceedingly unlikely, but they raise in extreme form the issue of who should decide, and how, whether to proceed with experiments that have a genuine scientific purpose (and could conceivably offer practical benefits), but that pose a very tiny risk of an