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The environmental consequences of a nuclear war
J. Aerosol Sci., Vol. 18. No. 6, pp. 589-591, 1987.
0021-8502/87 $3.00+0.00 Pergamon JournalsLtd
Printed in Great Britain
THE ENVIRONMENTALCONSEQUENCESOF A NUCLEARWAR The Report SCOPE28 - 1986 O. Preining Institute for Experimental Physics, University of Vienna.
You may ask why a Physicist choose this topic. I read the report: SCOPE 28 - and I feel obliged to discuss, this complex topic between science, p o l i t i c s , faith and emotions. Let's start with the facts: Two nuclear bombs were used during the last great war, their effects have seduced the military to develope nuclear weapons at a large scale. Huge stockpiles were accumulated in East and West over the years. More sophisticated weapons with specific properties - the "third generation nuclear weapons", to use an Eduard Teller phrase - are under development right now. But two aspect must be kept in mind: 1) Nuclear weapons are only just one part of the military potential to affect mankind globally at our days. 2) Nuclear weapons are offensive weapons but mutual retaliation systems were designed to destroy the people of an aggressor even i f at that moment the own population is already v i r t u a l l y extinct. This leads to the dogma: Peace by threat of mutual extinction. To recapitulate b r i e f l y - what is an atomic bomb ? The fission or fusion of certain heavy or respectively l i g h t atomic nuclei frees very large energies, byproducts of each fission are the production of neutrons. They induce further fission and a chain reaction starts heating up the material in a very short time to temperatures comparable to that in the i n t e r i o r of stars. Under these conditions also fusion occurs. Most of the energy is freed in the form of shortwave electro magnetic radiation -radiation. Air is impenetrable for that, the material of the bomb and the surrounding air is converted to an extreme hot Plasma, not in thermal equilibrium. This Plasma cools by expanding its mass and size, the f i r e b a l l forms, emitting l i g h t , x-rays, thermal radiation and producing a shock wave. Thermal flux and amplitude of the shock wave decrease with distance from the "center". What would happen in case a 1MT bomb explodes 2 km above the Empire State Building. The thermal radiation would ignite promptly some surfaces, but the shock wave would blow out the fires and destroy or damage heavily buildings all the way to Staton Island, secondary fires would then combine to a firestorm. The size of bombs is judged by i t s equivalent to conventional explosives. Trinitrotuluene was ic~osen as the yardstick, and physicists defined 1 kT TNT = 10 Cal. 1 kT corresponds to 100 railroad cars (or trucks) carrying 10 T each. The next question is: How many bombs are existing ? The answer is given by the SCOPE report: 50 000 bombs with a total equivalent of 12 000 MT TNT. This is about 2,4 T per living human being. Are we sure about the Ks~ler °~ of the arsenal ? Producing Plutonium releases the noble gas into the atmosphere ( H a l f l i f e of l i t t l e over 10 years). The measured steady increase permits to evaluate the global cumulative Plutonium production and that confirmes the
589
590
O. PRHNtNC;
estimates. The build up of Kr85 in the atmosphere is by i t s e l f environmentally questionable since one may speculate about the impact of i t on the conductivity of the atmosphere and in turn on the electric f i e l d of the earth or the potential for radiochemical reactions similar to photochemical reactions. To see the global stockpile in perspective, lets compare i t with the global energy produciton. The 12 000 MT correspond to approximately the annual or production of e l e c t r i c i t y . I/6 of total energy consumption of mankind per year and approx. 50 times the energy of a large volcanic eruption. However compared with the solar energy flux the energy content of the nuclear arsenal corresponds to only about 5 min. The environmental impacts of a nuclear war are f a c i l i t a t e d by the production of aerosols and their interference with the radiation balance. To judge the possible impact we have to know the global aerosol production f i r s t . Looking through the l i t e r a t u r e reveals the great uncertainties in our knowledge. All the estimates so far published show that they date back to a few early sources, particularly Junge's 1963 estimate (Jaenicke 1980,i~idy 1984, NRC 1985, Seinfeld 1986). A reasonable figure is 24.10~ g / y r total aerosol with c. 10 % soot. To make an estimate of the aerosol produced by a nuclear war we have to assume ~ s c e n a r i o , l e t ' s assume a 6000 MT scenario. This yields: about 4.10 ~ g aerosol is released, corresponding to about 2 months of the global aerosol production, however since 75 % is soot, the soot corresponds to an one year production. The possible mechanisms of influencing the climat is an interference with the radiation balance of the atmosphere. This could also change the global circulation pattern since the input is thought to be only in the northern hemisphere and is hence highly unsymmetric. How long would the influences last ? This depends on the residence time of the particles in the atmosphere. Here we encounter great uncertainity because we do not know whether or not the impact i t s e l f changes residence time. Based on Jaenicke's estimate the general assumption is that the dramatic effects will last for about 4 months. However, all the aerosol parameters are uncertain as Penner 1986 pointed out. Some of the investigations were made - as I see i t - to find ways to circumvene the unwanted effects of a nuclear war. The environmental effects are thought to be considerably less when the war occurs during early winter compared to late spring. The temperature decrease derived from different scenarios varies between 11 and 42°C, the half l i f e for recovery of the temperature between 26 and 300 days. Such changes in climat for the year of the nuclear war would have very serious consequences for the agricultural production. Economy and trade would be paralysed and the social order might break down completely. Different s e n s i t i v i t i e s , depending on the stockpile of food, are to be expected for different countries. The timing of the nuclear exchange will be very important. The two cases, median food stockpile (early winter war) and carry overs only (late spring war) give some hint of the problems a society may face, when, like in the case of India, of 685 million survivors only 53 millions can be fed for one year, global mass starvation and complete disruption of social order seem to be unavoidable. The conclusions of the SCOPE-report: The direct l~sses occur only in lattitudes north of 20° North, they are about 10 l i f e s . The f a t a l i t i e s of the environmental consequences are 2 to 3 times as many and are distributed over all latitudes. All countries are effected, regardless whether or not they were directly engaged in the war and whether they were attacked or not. The
Environmental consequences of a nuclear war
consequences via the environment are most important and would affect all mankind. References: Hidy, G.M., Aerosols: An Industrial and Environmental Science, Academic Press, Inc., Orlando, San Diego, San Francisco, New York, London, Toronto, Montreal, Sydney, Tokyo, Sao Paulo, 1984. Jaenicke, R., Journal of Aerosol Science, Vol. 11, (1980), 577. NRC, National Research Council, The effects on the Atmosphere of a f4ajor Nuclear Exchange, National Academy Press, Washington D.C., 1985 Penner, J.E., Nature 324 (1986) 222 - 226 SCOPE 28, Pittock A.B. e t a ] . ed's, Environmental Consequencesof Nuclear War, Wiley, Chichester, 1986. Seinfeld, J.H., Atmospheric Chemistry and Physics of Air Pollution, John Wiley & Sons, New York, Chichester, Brisbane, Toronto, Singapore, 1986.
591
0021-8502/87 $3.00+0.00 Pergamon JournalsLtd
Printed in Great Britain
THE ENVIRONMENTALCONSEQUENCESOF A NUCLEARWAR The Report SCOPE28 - 1986 O. Preining Institute for Experimental Physics, University of Vienna.
You may ask why a Physicist choose this topic. I read the report: SCOPE 28 - and I feel obliged to discuss, this complex topic between science, p o l i t i c s , faith and emotions. Let's start with the facts: Two nuclear bombs were used during the last great war, their effects have seduced the military to develope nuclear weapons at a large scale. Huge stockpiles were accumulated in East and West over the years. More sophisticated weapons with specific properties - the "third generation nuclear weapons", to use an Eduard Teller phrase - are under development right now. But two aspect must be kept in mind: 1) Nuclear weapons are only just one part of the military potential to affect mankind globally at our days. 2) Nuclear weapons are offensive weapons but mutual retaliation systems were designed to destroy the people of an aggressor even i f at that moment the own population is already v i r t u a l l y extinct. This leads to the dogma: Peace by threat of mutual extinction. To recapitulate b r i e f l y - what is an atomic bomb ? The fission or fusion of certain heavy or respectively l i g h t atomic nuclei frees very large energies, byproducts of each fission are the production of neutrons. They induce further fission and a chain reaction starts heating up the material in a very short time to temperatures comparable to that in the i n t e r i o r of stars. Under these conditions also fusion occurs. Most of the energy is freed in the form of shortwave electro magnetic radiation -radiation. Air is impenetrable for that, the material of the bomb and the surrounding air is converted to an extreme hot Plasma, not in thermal equilibrium. This Plasma cools by expanding its mass and size, the f i r e b a l l forms, emitting l i g h t , x-rays, thermal radiation and producing a shock wave. Thermal flux and amplitude of the shock wave decrease with distance from the "center". What would happen in case a 1MT bomb explodes 2 km above the Empire State Building. The thermal radiation would ignite promptly some surfaces, but the shock wave would blow out the fires and destroy or damage heavily buildings all the way to Staton Island, secondary fires would then combine to a firestorm. The size of bombs is judged by i t s equivalent to conventional explosives. Trinitrotuluene was ic~osen as the yardstick, and physicists defined 1 kT TNT = 10 Cal. 1 kT corresponds to 100 railroad cars (or trucks) carrying 10 T each. The next question is: How many bombs are existing ? The answer is given by the SCOPE report: 50 000 bombs with a total equivalent of 12 000 MT TNT. This is about 2,4 T per living human being. Are we sure about the Ks~ler °~ of the arsenal ? Producing Plutonium releases the noble gas into the atmosphere ( H a l f l i f e of l i t t l e over 10 years). The measured steady increase permits to evaluate the global cumulative Plutonium production and that confirmes the
589
590
O. PRHNtNC;
estimates. The build up of Kr85 in the atmosphere is by i t s e l f environmentally questionable since one may speculate about the impact of i t on the conductivity of the atmosphere and in turn on the electric f i e l d of the earth or the potential for radiochemical reactions similar to photochemical reactions. To see the global stockpile in perspective, lets compare i t with the global energy produciton. The 12 000 MT correspond to approximately the annual or production of e l e c t r i c i t y . I/6 of total energy consumption of mankind per year and approx. 50 times the energy of a large volcanic eruption. However compared with the solar energy flux the energy content of the nuclear arsenal corresponds to only about 5 min. The environmental impacts of a nuclear war are f a c i l i t a t e d by the production of aerosols and their interference with the radiation balance. To judge the possible impact we have to know the global aerosol production f i r s t . Looking through the l i t e r a t u r e reveals the great uncertainties in our knowledge. All the estimates so far published show that they date back to a few early sources, particularly Junge's 1963 estimate (Jaenicke 1980,i~idy 1984, NRC 1985, Seinfeld 1986). A reasonable figure is 24.10~ g / y r total aerosol with c. 10 % soot. To make an estimate of the aerosol produced by a nuclear war we have to assume ~ s c e n a r i o , l e t ' s assume a 6000 MT scenario. This yields: about 4.10 ~ g aerosol is released, corresponding to about 2 months of the global aerosol production, however since 75 % is soot, the soot corresponds to an one year production. The possible mechanisms of influencing the climat is an interference with the radiation balance of the atmosphere. This could also change the global circulation pattern since the input is thought to be only in the northern hemisphere and is hence highly unsymmetric. How long would the influences last ? This depends on the residence time of the particles in the atmosphere. Here we encounter great uncertainity because we do not know whether or not the impact i t s e l f changes residence time. Based on Jaenicke's estimate the general assumption is that the dramatic effects will last for about 4 months. However, all the aerosol parameters are uncertain as Penner 1986 pointed out. Some of the investigations were made - as I see i t - to find ways to circumvene the unwanted effects of a nuclear war. The environmental effects are thought to be considerably less when the war occurs during early winter compared to late spring. The temperature decrease derived from different scenarios varies between 11 and 42°C, the half l i f e for recovery of the temperature between 26 and 300 days. Such changes in climat for the year of the nuclear war would have very serious consequences for the agricultural production. Economy and trade would be paralysed and the social order might break down completely. Different s e n s i t i v i t i e s , depending on the stockpile of food, are to be expected for different countries. The timing of the nuclear exchange will be very important. The two cases, median food stockpile (early winter war) and carry overs only (late spring war) give some hint of the problems a society may face, when, like in the case of India, of 685 million survivors only 53 millions can be fed for one year, global mass starvation and complete disruption of social order seem to be unavoidable. The conclusions of the SCOPE-report: The direct l~sses occur only in lattitudes north of 20° North, they are about 10 l i f e s . The f a t a l i t i e s of the environmental consequences are 2 to 3 times as many and are distributed over all latitudes. All countries are effected, regardless whether or not they were directly engaged in the war and whether they were attacked or not. The
Environmental consequences of a nuclear war
consequences via the environment are most important and would affect all mankind. References: Hidy, G.M., Aerosols: An Industrial and Environmental Science, Academic Press, Inc., Orlando, San Diego, San Francisco, New York, London, Toronto, Montreal, Sydney, Tokyo, Sao Paulo, 1984. Jaenicke, R., Journal of Aerosol Science, Vol. 11, (1980), 577. NRC, National Research Council, The effects on the Atmosphere of a f4ajor Nuclear Exchange, National Academy Press, Washington D.C., 1985 Penner, J.E., Nature 324 (1986) 222 - 226 SCOPE 28, Pittock A.B. e t a ] . ed's, Environmental Consequencesof Nuclear War, Wiley, Chichester, 1986. Seinfeld, J.H., Atmospheric Chemistry and Physics of Air Pollution, John Wiley & Sons, New York, Chichester, Brisbane, Toronto, Singapore, 1986.
591