|Chapter from Unless Peace Comes 1968
HOW TO WRECK THE ENVIRONMENT
by Gordon J. F. MacDonald U.S.A.
Professor MacDonald is associate director of the Institute of Geophysics and Planetary Physics at the University of California, Los Angeles. His researches have embraced a remarkable diversity of natural phenomena and his professional interests are further extended by his participation in national science policy-making. He is a member of President Johnson’s Science Advisory Committee.
Among future means of obtaining national objectives by force, one possibility hinges on man’s ability to control and manipulate the environment of his planet. When achieved, this power over his environment will provide man with a new force capable of doing great and indiscriminate damage. Our present primitive understanding of deliberate environmental change makes it difficult to imagine a world in which geophysical warfare is practised. Such a world might be one in which nuclear weapons were effectively banned and the weapons of mass destruction were those of environmental catastrophe.
Alternatively, I can envisage a world of nuclear stability resulting from parity in such weapons, rendered unstable by the development by one nation of an advanced technology capable of modifying the Earth’s environment. Or geophysical weapons may be part of each nation’s armoury. As I will argue, these weapons are peculiarly suited for covert or secret wars.
Science fiction literature contains many suggestions of how wars would progress if man indeed possessed the ability to change weather, climate, or ocean currents. Many of these fictional suggestions, and other more serious discussions, fail to take into account the limitations of nature. Jules Verne gave a detailed discussion of displacing the Earth’s polar caps, thus making the world’s climatic zones more equitable (Les Voyages Extraordinaires; Sans Dessus Dessous, Metzel, 1889). Verne’s proposal was to eliminate the 23º tilt in the Earth’s axis, putting it at right angles to the Sun-Earth plane. However, as Verne correctly pointed out in a subsequent discussion, the Earth’s equatorial bulge stabilizes our planet and even the launching of a 180,000-ton projectile would produce a displacement of only 1/10 micron. Senator Estes Kefauver, Vice-Presidential candidate in the 1956 American election, rediscovered Verne’s original proposal and was seriously concerned with the tipping of the Earth’s axis. He reported that the Earth’s axis could, as the result of an H-bomb explosion, be displaced by 10º. Either Senator Kefauver or his scientific advisers neglected the stabilizing influence of the Earth’s bulge. The maximum displacement that can be expected from the explosion of a 100-megaton H-weapon is less than one micron, as Walter Munk and I pointed out in our book, Rotation of the Earth (Cambridge, 1960).
Substantial progress within the environmental sciences is slowly overcoming the gap between fact and fiction regarding manipulations of the Earth’s physical environment. As these manipulations become possible, history shows that attempts may be made to use them in support of national ambitions. To consider the consequences of environmental modification in struggles among nations, we need to consider the present state of the subject and how postulated developments in the field could lead, ten to fifty years from now, to weapons systems that would use nature in new and perhaps unexpected ways.
The key to geophysical warfare is the identification of the environmental instabilities to which the addition of a small amount of energy would release vastly greater amounts of energy. Environmental instability is a situation in which nature has stored energy in some part of the Earth or its surroundings far in excess of that which is usual. To trigger this instability, the required energy might be introduced violently by explosions or gently by small bits of material able to induce rapid changes by acting as catalysts or nucleating agents. The mechanism for energy storage might be the accumulation of strain over hundreds of millions of years in the solid Earth, or the super-cooling of water vapour in the atmosphere by updraughts taking place over a few tens of minutes. Effects of releasing this energy could be world-wide, as in the case of altering climate, or regional, as in the case of locally excited earthquakes or enhanced precipitation.
The Earth’s atmosphere is an envelope of air which rotates, for the most part, at the same speed as the underlying continents and oceans. The relative motion between the atmosphere and the Earth arises from sources and sinks of energy which vary in location and strength but which have, as their ultimate source, the Sun’s radiation. The quantities of energy involved in weather systems exceed by a substantial margin the quantity of energy under man’s direct control.
For instance, the typical amount of energy expended in a single tornado funnel is equivalent to about fifty kilotons of explosives; a single thunderstorm tower exchanges about ten times this much energy during its lifetime; an Atlantic hurricane of moderate size may draw from the sea more than 1,000 megatons of energy. These vast quantities of energy make it unlikely that brute-force techniques will lead to sensible weather modification. Results could be achieved, however, by working on the instabilities in the atmosphere.
We are now beginning to understand several kinds of instabilities in the atmosphere. Supercooled water droplets in cold clouds are unstable, but they remain liquid for substantial periods of time unless supplied with nuclei on which they can freeze. Conversion of water droplets to ice through the introduction of artificial nuclei can provide a local source of energy. This released heat can cause rising air currents which in turn lead to further formation of supercooled water. This process may lead to rainfall at the ground greater than that which would have been produced without the artificial nucleation. A second instability may arise, in which water vapour condenses into water, again affecting the distribution of sensible energy. On a larger scale, there is the so-called baroclinic instability of atmospheric waves that girdle the planet. Through the imbalance of heat between equator and pole, energy in this instability is stored, to be released in the creation of large cyclonic storms in the temperate zones. There are other, less well understood instabilities capable of affecting climate; I shall return to them later.
What is the present situation with respect to weather modification and what might be reasonably expected in the future? Experiments over the past eighteen years have demonstrated unequivocally that clouds composed of supercooled water droplets can be transformed into ice-crystal clouds by seeding them with silver iodide, ‘dry ice’ (frozen carbon dioxide) and other suitable chemical agents. This discovery has been applied operationally in the clearance of airports covered by supercooled ground fog. No analogous technique has yet evolved for clearing warm fog, although several promising leads are now being investigated. In the case of warm fog, the atmospheric instability is that water vapour distributed in small drops contains more surface energy than the same water distributed in large drops. The trick for clearance of this warm fog will be to discover some way of getting the small drops to organize themselves into larger ones and then fall to the ground.
There is increasing, though inconclusive, evidence that rainfall from some types of clouds and storm systems in temperate regions can be increased by ten to fifteen per cent by seeding. Somewhat more controversial evidence indicates that precipitation can be increased from tropical cumulus by techniques similar to those employed in temperate regions. Preliminary experiments on hurricanes have the aim of dissipating the clouds surrounding the eye of the storm in order to spread the energy of the hurricane and reduce its force. The results are controversial but indicate that seeding can, in certain circumstaaces, lead to a marked growth in the seeded cloud. This possibility may have merit in hurricane modification, but experimentation has not yet resulted in a definitive statement.
Regarding the suppression of lightning, there is mixed but largely promising evidence that the frequency of cloud-to-ground strokes can be reduced by the introduction of ‘chaff’, strips of metallic foil of the kind used for creating spurious echoes in enemy radars.
In looking to the future, it is quite clear that substantial advances will be made in all of these areas of weather modification. Today, both military and civilian air transport benefit from progress in the clearance of ground fog. Further progress in the technology of introducing the seeding agent into the fog makes it likely that this type of fog dispersal will become routine. In a sense, fog clearing is the first military application of deliberate manipulation of weather, but it is, of course, very limited.
Large field programmes are being undertaken in the United States to explore further the possibility of enhancing precipitation, particularly in the western and north-eastern states. On the high ground of the western states, snow from winter storms provides much of the country’s moisture. Investigations are under way to see if seeding can lead to an increased snowpack and thus enhance the water resources. Intense interest in this form of weather modification, coupled with an increased investigation of the physics of clouds, is likely to lead to effective cloud modification within the next five to fifteen years. At present, the effects are measured only statistically and too little has been done in cloud observation before and after seeding in the way of precisely pinpointing which clouds are most likely to be affected.
As far as military applications are concerned, I conjecture that precipitation enhancement would have a limited value in classical tactical situations, and then only in the future when controls are more thoroughly understood. One could, for example, imagine field commanders calling for local enhancement of precipitation to cover or impede various ground operations. An alternative use of cloud seeding might be applied strategically. We are presently uncertain about the effect of seeding on precipitation down wind from the seeded clouds. Preliminary analysis suggests that there is no effect 200-300 miles down wind, but that continued seeding over a long stretch of dry land clearly could remove sufficient moisture to prevent rain 1,000 miles down wind. This extended effect leads to the possibility of covertly removing moisture from the atmosphere so that a nation dependent on water vapour crossing a competitor country could be subjected to years of drought. The operation could be concealed by the statistical irregularity of the atmosphere. A nation possessing superior technology in environmental manipulation could damage an adversary without revealing its intent.
Modification of storms, too, could have major strategic implications. As I have mentioned, preliminary experiments have been carried out on the seeding of hurricanes. The dynamics of hurricanes and the mechanism by which energy is transferred from the ocean into the atmosphere supporting the hurricane are poorly understood. Yet various schemes for both dissipation and steering can be imagined. Although hurricanes originate in tropical regions, they can travel into temperate latitudes, as the residents of New England know only too well. A controlled hurricane could be used as a weapon to terrorize opponents over substantial parts of the populated world.
It is generally supposed that a hurricane draws most of its energy from the sea over which it passes. The necessary process of heat transfer depends on wave action which permits the air to come in contact with a volume of water. This interaction between the air and water also stirs the upper layers of the atmosphere and permits the hurricane to draw on a substantially larger reservoir of heat than just the warm surface water. There may be ways, using monomolecular films of materials like those developed for covering reservoirs to reduce evaporation, for decreasing the local interaction between sea and air and thus preventing the ocean from providing energy to the hurricane in an accelerated fashion. Such a procedure, coupled with selective seeding, might provide hurricane guidance mechanisms. At present we are a long way from having the basic data and understanding necessary to carry out such experiments; nevertheless, the long-term possibility of developing and applying such techniques under the cover of nature’s irregularities presents a disquieting prospect.
In considering whether or not climate modification is possible, it is useful to examine climate variations under natural conditions. Firm geological evidence exists of a long sequence of Ice Ages, in the relatively recent past, which shows that the world’s climate has been in a state of slow evolution. There is also good geological, archaeological and historical evidence for a pattern of smaller, more rapid fluctuations superimposed on the slow evolutionary change. For example, in Europe the climate of the early period following the last Ice Age was continental, with hot summers and cold winters. In the sixth millennium B.C., there was a change to a warm humid climate with a mean temperature of 5ºF higher than at present and a heavy rainfall that caused considerable growth of peat. This period, known as a climatic optimum, was accentuated in Scandinavia by a land subsidence which permitted a greater influx of warm Atlantic water into the large Baltic Sea.
The climatic optimum was peculiar. While on the whole there was a very gradual decrease of rainfall, the decrease was interrupted by long droughts during which the surface peat dried. This fluctuation occurred several times, the main dry periods being from 2000 to 1900, 1200 to 1000 and 700 to 500 B.C. The last, a dry heat wave lasting approximately 200 years, was the best developed. The drought, though not sufficiently intense to interrupt the steady development of forests, did cause extensive migrations of peoples from drier to wetter regions.
A change to colder and wetter conditions occurred in Europe about 500 B.C. and was by far the greatest and most abrupt alteration in climate since the end of the last Ice Age. It had a catastrophic effect on the early civilization of Europe: large areas of forest were killed by the rapid growth of peat and the levels of the Alpine lakes rose suddenly, flooding many of the lake settlements. This climatic change did not last long; by the beginning of the Christian era, conditions did not differ greatly from current ones. Since then climatic variations have continued to occur and although none has been as dramatic as that of 500 B.C. a perturbation known as the little ice age of the seventeenth century is a recent noteworthy example. The cause of these historical changes in climate remains shrouded in mystery, The rapid changes of climate in the past suggest to many that there exist instabilities affecting the balance of solar radiation.
Indeed, climate is primarily determined by the balance between the incoming short-wave from the Sun (principally light) and the loss of outgoing long-wave radiation (principally heat).
Three factors dominate the balance: the energy of the Sun, the surface character of terrestrial regions (water, ice, vegetation, desert, etc.), and the transparency of the Earth’s atmosphere to different forms of radiated energy. In the last connection, the effect of clouds in making cool days and relatively warm nights is a matter of familiar experience. But clouds are a manifestation rather than an original determinant of weather and climate; of more fundamental significance is the effect of gases in the atmosphere, which absorb much of the radiation in transit from the Sun to the Earth or from the Earth into space. Intense X-rays and ultra-violet from the Sun, together with high-energy atomic particles, are arrested in the upper atmosphere. Only the narrow band of visible light and some short radio waves traverse the atmosphere without serious interruption.
There has been much controversy in recent years about conjectured overall effects on the world’s climate of emissions of carbon dioxide to the atmosphere from furnaces and engines burning fossil fuels, and some about possible influences of the exhaust from large rockets on the transparency of the upper atmosphere. Carbon dioxide placed in the atmosphere since the start of the industrial revolution has produced an increase in the average temperature of the lower atmosphere of a few tenths of a degree Fahrenheit. The water vapour that may be introduced into the stratosphere by the supersonic transport may also result in a similar temperature rise. In principle it would be feasible to introduce material into the upper atmosphere that would absorb either incoming light (thereby cooling the surface) or outgoing heat (thereby warming the surface). In practice, in the rarefied and windswept upper atmosphere, the material would disperse rather quickly, so that military use of such a technique would probably rely upon global rather than local effects. Moreover, molecular material will tend to decompose, and even elemental materials will eventually be lost by diffusion into space or precipitation to the surface. At intermediate levels, in the stratosphere, materials may tend to accumulate though the mixing time for this part of the atmosphere is certainly less than ten years and may be a few months. If a nation’s meteorologists calculated that a general warming or cooling of the Earth was in their national interest, improving their climate while worsening others, the temptation to release materials from high-altitude rockets might exist. At present we know too little about the paradoxical effects of warming and cooling, however, to tell what the outcome might be.
More sudden, perhaps much briefer but nevertheless disastrous effects, are predictable if chemical or physical means were developed for attacking one of the natural constituents of the atmosphere ozone. A low concentration of ozone (03, a rare molecular form of oxygen) in a layer between fifteen and fifty kilometres altitude has the utmost significance for life on land. It is responsible for absorbing the greater part of the ultra-violet from the Sun. In mild doses, this radiation causes sunburn; if the full force of it were experienced at the surface, it would be fatal to all life – including farm crops and herds – that could not take shelter. The ozone is replenished daily, but a temporary ‘hole’ in the ozone layer over a target area might be created by physical or chemical action. For example, ultra-violet at 250 millimicrons wavelength decomposes ozone molecules, and ozone reacts readily with a wide range of materials.
At present, we can only tentatively speculate about modifying the short-wave radiation at its source, the Sun. We have discovered major instabilities on the Sun’s surface which might be manipulated many years hence. In a solar flare, for example, 1010 megatons of energy are stored in distorted magnetic fields. With advanced techniques of launching rockets and setting off large explosions, we may sometime in the future learn to trigger these instabilities. For the near future, however, modification will not be in the short-wave in-coming radiation but in the long-wave outgoing radiation.
The usual schemes for modifying climate involve the manipulation of large ice fields. The persistence of these large ice fields is due to the cooling effects of the ice itself, both in reflecting (rather than absorbing) incoming short-wave radiation and in radiating heat at a higher rate than the usual ground cover. A commonly suggested means of climate modification involves thin layers of coloured material spread on an icy surface, thus inhibiting both the reaction and radiation processes, melting the ice, and thereby altering the climate. Such a procedure presents obvious technical and logistic difficulties. For example, if one wished to create a surface coating of as little as one micron thickness to cover a square 1,000 kilometres in size, the total material for this extremely thin coating would weigh a million tons or more, depending upon its density. So the proposals to dust from the air some of the globe’s extended ice sheets, are unrealistic and reflect a brute-force technique, taking no advantage of instabilities within the environment.
While it may be technologically difficult to change an ice cap’s surface character, and thus its thermal properties, it may be possible to move the ice, taking into account the gravitational instability of ice caps. The gravitational potential energy of water as a thick, high ice cap is much greater than it would be at sea level. This fact makes it possible, at least in principle, to devise schemes for bringing about a redistribution in the ice. Indeed, A. T. Wilson has proposed a cyclical theory for the Ice Ages based on this instability.
The main points of Wilson’s theory are as follows:
Antarctica is covered by an ice sheet several kilometres thick. Pressure at the bottom of the ice is great enough to keep the ice at or near its melting point; water is an unusual material in that a pressure increase lowers rather than raises its melting point. An increase in thickness of the ice sheet could result in melting at the bottom. The resulting ice-water mixture along the sole of the glacier would permit flow by a process of freezing and melting – a flow process much more effective than ordinary plastic fiow.
If such an instability occurs, the ice sheet will flow out on to the surrounding sea and a large ice shelf will be formed between An-tarctica and the ocean around it. As a consequence, short-wave solar radiation will be reflected and there will be enhanced loss of heat by radiation at the long wave-lengths, causing cooling and the inducement of world-wide glaciation.
Once the ice shelf is in the ocean, it will begin to melt and eventually will be removed. The ice remaining on land will be much thinner than before. As the reflectivity of the southern hemisphere decreases with the melting of the Antarctic ice cap, the global climate will grow warmer again, corresponding to the start of an interglacial period. The ice cap will slowly form again.