Silencing the Bomb Page 28

  NUCLEAR WINTER

  Over the past several decades, a number of authors have proposed that the detonation of large numbers of nuclear weapons could have profound and severe effects on climate, especially in the Northern Hemisphere. This, in turn, could damage crops and potentially cause as much loss of life as the immediate effects of blast, thermal radiation, fire, and fallout. Several examples of devastating destruction are known throughout Earth’s history. A 1980 paper in Science by Luis Alvarez, a Nobel Prize–winning physicist, and his colleagues described a global disaster 65 million years ago that they concluded resulted in huge decreases in temperature on Earth. They stimulated research on what R. P. Turco and his colleagues in 1983 termed “nuclear winter.”

  Alvarez and his colleagues sought to explain the sudden demise of the dinosaurs and many other species at the end of the Mesozoic era and the start of the Cenozoic geological era in Earth history. They proposed that Earth was hit by a large comet or asteroid that lofted debris high into the atmosphere and ignited multiple firestorms in forests. They sampled sediments at the Mesozoic-Cenozoic boundary at Gubbio, Italy, and reported unusually high concentrations of the element Iridium. Iridium, one of the platinum group of elements, is known to be more plentiful in meteorites than on earth. They concluded that the impact caused global decreases in temperature, loss of vegetation, and winter conditions that lasted long enough that many animals, such as dinosaurs, died of starvation.

  The impact site was subsequently identified near the north coast of Mexico’s Yucatán Peninsula. Dated sedimentary deposits along the northern Gulf of Mexico indicate that a huge sea wave (tsunami) hit those shores soon after the impact. Damage to living species was particularly high in North America to the northwest of the impact site, leading to the conclusion that the impacting body traveled in a northwesterly direction before hitting Yucatán.

  Large volcanic eruptions, especially those that release large amounts of sulfur dioxide into the atmosphere, are known to cause drops in global temperature for one to a few years. The large eruption of the Indonesian volcano Krakatoa in 1883 caused global cooling of about 1.8°F (1°C) for two years. The even larger eruption of the earlier Indonesian volcano Tambora in 1815, one of the most powerful in recorded history, was followed by “the year without a summer.” Temperature decreases after such large volcanic eruptions are useful tests of models of longer-term climate changes and the role of human-induced global warming.

  I have selected one article that examines possible climatic changes associated with a major nuclear exchange between the Soviet Union and the United States and another that describes the effects of an exchange between India and Pakistan.

  Scientists Turco, A. B. Toon, T. P. Ackerman, J. B. Pollack, and C. Sagan—referred to widely as TTAPS—made computer simulations for their 1983 article in Science of a number of scenarios involving the exchange of nuclear weapons between the Soviet Union and the United States. Their baseline exchange involved 10,400 explosions with yields of 100 to 10,000 kilotons (0.1 to 10 megatons [Mt]). Fortunately, this example is not valid today because bilateral treaties have reduced the numbers of warheads of the two nuclear superpowers (see figure 17.1). Also, the maximum yields of warheads decreased as more missiles with multiple warheads were deployed and bomber payloads transitioned from mostly high-yield bombs to many missiles with weapons of lower yield.

  TTAPS scenarios 12 and 14 are more appropriate today. Case 12 involved an exchange of 2250 warheads with yields of 200 to 1000 kilotons; two-thirds were focused on hardened targets like missile silos and the remaining one-third on urban and industrial targets. Scenario 14 involved 1000 warheads with yields of 100 kilotons (ten times smaller than in case 12) used solely against urban and industrial targets. According to TTAPS, both of these scenarios would still have great long-term consequences. A major exchange aimed at military and industrial targets alone would not be just a “surgical strike” with damage limited to those facilities, because many are located within or near urban zones. In addition to radioactive fallout, widespread fires would occur after most nuclear bursts over forests and cities.

  TTAPS also focused on the potential effects on climate of huge amounts of smoke and dust carried into the atmosphere by a major exchange, which would cause cooling of the lower atmosphere by blocking sunlight from reaching the surface of the Earth. Scenario 12, while less severe in its absolute impact than their baseline scenario, was projected to affect the atmosphere to an extent comparable to or exceeding that of a major volcanic eruption such as Tambora in 1815 and its following “year without a summer.” They stated, “Unexpectedly, less than 1 percent of existing [1983] strategic arsenals, if targeted on cities, could produce optical (and climatic) disturbances much larger than those previously associated with a massive nuclear exchange ~10,000 MT.” For case 12, 1 percent in 1983 is roughly equivalent to 10 percent of the reduced strategic arsenals of the United States and Russia in 2017.

  The Earth’s atmosphere consists of the troposphere, which extends from the surface to an altitude of about 6 to 8 miles (10 to 13 km). Above the troposphere is the stratosphere, which extends to an altitude of 30 miles (50 km).

  TTAPS found that more than two to three months after a major nuclear exchange, while soot would be largely depleted in the atmosphere by rainfall and washout, dust would dominate optical effects. In case 14, none of the smoke from urban fires in about a hundred cities would reach the stratosphere, whereas for many of their other scenarios it would. TTAPS found that fine dust in the stratospheric would be responsible for prolonged cooling lasting a year or more.

  TTAPS calculated average cooling of land areas in the Northern Hemisphere as large as about 58o F (32o C) for case 14, the city attack, and about 11o F (6o C) for case 12. This was so even though case 14 involved only 10 percent of the megatonnage of case 12. Significant temperature changes would last about a hundred days for case 14 and about twenty to eighty days for case 12. This would mean subfreezing temperatures in many places even in the summer for case 14. According to TTAPS, much of the population of the Earth might survive the immediate consequences of a nuclear war, but “the longer-term and global-scale aftereffects of nuclear war might prove to be as important as the immediate consequences of the war [i.e., the effects from blast, thermal radiation, and fallout].”

  In the decades after these early 1980s, studies on nuclear winter, computer power, and global circulation models of the atmosphere and oceans improved immensely, with three-dimension models replacing one-dimensional ones. In 2007, some of the authors of the 1983 TTAPS study revisited the subject using a modern climate model with current nuclear arsenals. They reached similar conclusions about firestorms created by attacks on about a hundred cities (like case 14 of 1983) and calculated temperatures plunging below freezing in the summer in major agricultural regions, threatening food supplies for much of the planet. Climatic effects of smoke from burning cities and industrial areas, lofted into the upper stratosphere, would last for several years, longer than they originally thought in 1983.

  Also in 2007, Toon, one of the TTAPS authors, and colleagues did a computer analysis of a major exchange of nuclear weapons between Pakistan and India. They assumed that one hundred Hiroshima-size weapons of about 15 kilotons each were used to attack the densest population centers in each country—generally huge megacities. They concluded that those explosions would generate substantial global-scale temperature anomalies, though not as large as in a major exchange between the United States and Russia. The effects would degrade agricultural productivity to an extent that has led historically to famines in Africa, India, and Japan.

  Wikipedia describes work and speculation about the effects of the burning of oil wells in Kuwait that were ignited by Saddam Hussein of Iraq in 1991 during the first Gulf War. About 600 wells were ignited; some were not extinguished for more than six months. Prior to their being ignited, Turco, J. W. Birks, Carl Sagan, A. Robock, and P. Crutzen stated to reporters from two newspapers that they
expected catastrophic nuclear winter effects if Iraq went through with its threats to ignite 300 to 500 oil wells and if they burned for a few months.

  S. Fred Singer of the University of Virginia, a prominent denier of climate changes from human activities, and Sagan of Cornell University debated possible impacts of oil well fires in Kuwait on a TV news program. Sagan argued that some of the effects of the smoke lofting into the stratosphere could be similar to effects of nuclear winter and very similar to those from the eruption of Tambora in 1815. Singer, however, said his calculations showed that the smoke would rise to 3000 feet (900 m) and would be rained out in several days.

  Sagan later conceded that his predictions did not turn out to be correct. He said, “it was pitch black at noon and temperatures dropped 7 to 11o F (4 to 6o C) over the Persian Gulf but not much smoke reached stratospheric [higher] altitudes and Asia was spared.”

  A 2007 study by Toon and others applied modern computer models to the Kuwait oil fires and found that individual smoke plumes were not able to loft smoke into the stratosphere. Nevertheless, smoke from fires over a larger area could extend into the stratosphere.

  In the troposphere, the lower part of the atmosphere, temperature decreases with height; the troposphere turns over by convection and hence “washes itself out” with rain. The stratosphere, however, is more stratified (layered) because temperature there increases with height. Thus, small soot particles that make it into the stratosphere can remain there for a long time.

  Criticisms of the “nuclear winter” concept and the effects on the atmosphere of the fires in Kuwait led many U.S. policy makers to ignore the possible consequences of a nuclear winter. One statement called it “nuclear fall.” Note that the papers I have cited by Turco, Toon, and others were published in prominent refereed journals, whereas the remarks by Sagan and Singer were not. In 1987, Michael Kelly of Cambridge University and the British Climatic Research Unit stated, “although there are a handful of vociferous critics, the atmospheric community is united in its conclusion that the threat of nuclear winter is genuine.”

  After the breakup of the Soviet Union in 1989, relatively little work was published on nuclear winter. I strongly believe a vigorous debate on the subject is needed today. Even without as severe climatic effects as proposed by TTAPS in 1983, it is hard to dismiss the huge climatic effects from a major nuclear exchange.

  ACCOMPLISHMENTS OF SEISMOLOGISTS IN MONITORING A FULL TEST BAN TREATY

  Since the first calls for a CTBT in the 1950s, seismological instrumentation and techniques to monitor nuclear testing have improved immensely. None of the states possessing nuclear weapons that signed the CTBT in 1996 has detonated a nuclear explosion of military significance for twenty years. The CTBT has acted as a barrier to the development and testing of new generations of nuclear weapons. Serious evasion schemes, while still topics of political and occasional scientific debate, are considered exceedingly difficult to conduct without being detected by seismic methods, radionuclide sampling, and satellite imagery. Methods to muffle nuclear explosions in underground cavities have been determined to be unfeasible down to very small yields. Over the past fifty-five years since I became a graduate student at Columbia, the field of seismology has come full circle, finally fulfilling its long-thwarted promise to verify a nuclear test ban.

  PSYCHOLOGICAL ASPECTS OF THE NUCLEAR ARMS RACE

  I have read a number of publications by two psychiatrists, Robert Jay Lifton and Jerome Frank, who have written on psychological aspects of the nuclear arms race. I was fortunate to meet briefly with Frank at Johns Hopkins University when I gave an invited lecture on verifying a full test ban treaty. Frank, who died in 2005, was one of the founders of Physicians for Social Responsibility. I recommend his 1982 book Sanity and Survival in the Nuclear Age: Psychological Aspects of War and Peace.

  Following his work on Hiroshima survivors, Lifton became a vocal opponent of nuclear weapons. He argued that nuclear strategy and war-fighting doctrines made even mass genocide banal and conceivable. Among his books, I recommend The Broken Connection: On Death and the Continuity of Life (Simon & Schuster, 1979) and Indefensible Weapons: The Political and Psychological Case against Nuclearism (Basic Books, 1982). Very little attention is devoted to this important topic in the United States.

  WHY I WORK ON SUCH A FRIGHTENING TOPIC

  I am sometimes asked why I work on such a frightening and depressing topic. I explain to myself that this is the major issue of my lifetime. With my scientific knowledge, I hope to contribute in some small way to preventing the use of nuclear weapons. I regard this as my duty as an informed citizen, especially in a country that possesses vast numbers of nuclear weapons. I hope this book will convince others to learn more about these issues and to become more involved. I support the advice of Edmund Burke, the British-Irish orator, political theorist, and philosopher, who said, “Nobody made a greater mistake than the one who did nothing because they could only do a little.”

  A major nuclear exchange would be a cataclysmic disaster with a level of destruction unprecedented in the entire history of our species. Some people have argued that because nuclear weapons have not been used since 1945, the probability of their use is very small. The world has been fortunate that nuclear weapons have not been used since then, but this could end at a moment’s notice. False alarms, accidents, and the near miss of the Cuban missile crisis are not very reassuring about nuclear weapons’ not being used in the future. The probability per year of a nuclear exchange may be low, but if it happens, the consequences will be catastrophic. Getting the public and governments to deal with rare but catastrophic events is difficult but very necessary.

  The Trump administration has made threatening remarks about nuclear weapons. As of mid-2017 it is not clear if it might either use nuclear weapons against an advisory such as North Korea or resume nuclear testing. If it resumed testing, the yields of explosions likely would be large, abrogating several arms control agreements, and other countries almost certainly would resume testing.

  Since 1947, the Bulletin of the Atomic Scientists has published a Doomsday Clock symbolizing the dangers to humanity of a nuclear exchange (figure 18.1). It has been set between two and seventeen minutes to midnight at various times since 1947. In early 2017 it was reset from three to two and a half minutes to midnight.

  FIGURE 18.1

  The Doomsday Clock of the Bulletin of the Atomic Scientists. October 2016.

  GLOSSARY AND ABBREVIATIONS

  ABM (ANTI-BALLISTIC MISSILE)—A missile to knock down other missiles

  ABM TREATY—Treaty between United States and USSR on limitation of ABMs

  AEDS (ATOMIC ENERGY DETECTION SYSTEM)—Operated by AFTAC

  AFTAC (AIR FORCE TECHNICAL APPLICATIONS CENTER)—Does classified monitoring

  BMD (BALLISTIC MISSILE DEFENSE)—Proposals to destroy incoming missiles with missiles

  BOOSTED WEAPON—Addition of hydrogen isotopes to a weapon to make it lighter

  CD—UN’s Conference on Disarmament

  CTBT (COMPREHENSIVE TEST BAN TREATY)—Ban on testing of nuclear explosions of all yields

  CTBTO (COMPREHENSIVE TEST BAN TREATY ORGANIZATION)—UN Agency for CTBT

  CUBAN MISSILE CRISIS—Attempt by USSR to introduce nuclear weapons into Cuba in October 1962 and U.S. response

  DECOUPLED NUCLEAR TEST—Test fired in a large underground cavity so as to reduce the size of seismic waves produced

  EPICENTER—Location of seismic event in latitude and longitude

  EVERNDEN, JACK—Seismologist involved with test bans

  FAT MAN—Weapon tested in New Mexico and dropped on Nagasaki in 1945

  FISSILE MATERIAL—Certain isotopes of uranium and plutonium capable of undergoing nuclear fission

  FISSION—Splitting heavier into lighter elements

  FUSION—Fusing hydrogen isotopes into helium

  HERRIN, GENE—Seismologist involved with nuclear tests

  HEU (HIGHLY ENRICHED URANIUM)�
�High percentage of uranium 235

  HYDROACOUSTIC MONITORING—Detecting sound waves propagated in water

  HYPOCENTER—Location of seismic event in three dimensions

  IAEA (INTERNATIONAL ATOMIC ENERGY AGENCY)—UN agency based in Vienna

  ICBM—Intercontinental ballistic missile

  IMS (INTERNATIONAL MONITORING SYSTEM)—Monitors CTBT internationally

  INF (INTERMEDIATE-RANGE NUCLEAR FORCES) TREATY—Treaty between United States and USSR for systems capable of delivering nuclear weapons between short and intercontinental distances

  INFRASOUND MONITORING—Detecting very low frequency sound waves propagated in the atmosphere

  ISOTOPES—Varieties (flavors) of an element with different numbers of neutrons but the same number of protons in the atomic nucleus

  KAZAKHSTAN—Country in Central Asia, formerly part of USSR

  KIRGHIZSTAN—Country in Central Asia, formerly part of USSR

  KT (KILOTON)—Energy equivalent to 1000 tons of TNT

  LEP (LIFE EXTENSION PROGRAM)—Longer lifetime for a U.S. nuclear weapon

  LITTLE BOY—Weapon dropped on Hiroshima in 1945

  LOP NOR—Nuclear test site of China