danc@orca.UUCP (Daniel Cobb) (02/11/84)
Before I get started, I would like to say hello to those people on the net in Europe. Hi Europe! How nice it is that we have this capacity to communicate! Greetings!! About the nuclear winter that Sagan and his followers have been telling us about. -A recent artice in the Wall Street Journal disagrees with Sagan's nuclear winter hypothesis. The article was written by a Geophysicist from the University of Virginia, a Mr. Fred Singer. In short, the article says that there are two environmental models that can be used to estimate the effects of a large nuclear exchange. They are the planets Mars, and Venus. On Mars, intense dust storms have blocked out a great deal of sunlight, thus lowering the surface temperature of the planet. But on Venus, a greenhouse mechanism (associated with particles in the atmosphere) has warmed the surface of the planet to 700 degrees Farenheit. The article is far more technical and specific but it says that the Martian model does not apply to our situation because of differences in the optical properties of the particles in the Martian atmosphere and the particles that would be placed in the Earth's atmosphere by a nuclear war. Obviously Venus is far closer to the Sun than Mars or the Earth, and the 700 degrees surface temperature of Venus reflects this proximity. So it seems that a warming of the Earth is more probable. After all, the surface warming is not caused only by direct solar radiation, but by the fact that particles in the atmosphere will not allow the surface to to cool as rapidly. We are experiencing this very effect now, with a general warming the planet surface due to the burning of fossil fuels. Sagan also says that intense ultraviolet radiation would reach the surface due to a breakdown of the ozone layer, thereby creating a hazard to life, but Singer says that if general solar radiation is screened by dust and smoke, so will ultraviolet radiation, and that a rapid rebuilding of the upper ozone layer would occur shortly thereafter anyway. Singer also goes on to say that a temperature differences in the atmosphere caused by these particles would bring about intense thunderstorms, cleaning the atmosphere. Obviously nuclear war would be horrible, but are we perhaps overestimating the effects? Singer presents a good deal of information, and the article closes with an interesting question, although modified here. Does the prediction of a nuclear war make it less likey to happen? If so, should scientists ignore studies that indicate less severe environmental effects, and publicize those studies that dramatize the worst possible outcome, in effect seriously and artificially weighting there conclusions? Would this be lying?
edhall@randvax.ARPA (Ed Hall) (02/15/84)
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Why not look up the Science article in question? It is on page 1283 of
the December 23, 1983 issue. You'll find that Dr. Singer's rebuttal
just doesn't wash. Some items:
1) The theory doesn't just consider dust, but the enormous amount
of soot and smoke produced by bomb-induced fires. These sub-
micron particles behave differently from the volcanic dust
measurements that earlier models have been based on. Also,
nuclear weapons are far better at injecting dust into the
stratosphere (higher atmosphere) than volcanos.
2) The lower stratosphere and upper troposphere are indeed heated
in this model, while the lower troposphere (nearest the ground) is
cooled. Comparing an absorbing atmosphere such as this to the
diffusive one of Venus is ridiculous. The Venusian atmosphere is
extremely dense and CO2-laden. Earth's wasn't, last time I checked.
3) One possible effect of this hot-layered-over-cold model is the
supression of the convection mechanism which leads to storms.
This can slow the `raining-out' of the dust and smoke.
4) The model predicts a much longer time for the ozone layer to
recover than for the lower atmosphere to clear, with the net
result being a couple months of strong cooling followed by several
months of elevated ultraviolet radiation.
5) The article openly admits that it is considering some `worst-
case' scenarios. It also presents some possible milder outcomes.
Uncertainties are clearly identified.
6) Far from being written by `Carl Sagan and his followers', Sagan
is only a minor author; principal author is Dr. R. P. Turco.
[I have to admit that Sagan has sadly disappointed me with the
dogmatism of his public pronouncements. I hope his science is
better than his politics.]
Now, I'm not convinced that the Nuclear Winter theory is a fact, nor
am I convinced it is false. It will be refined or rejected with time.
The above is my own personal opinion, and has no relation to the opinion
or research of my employer.
-Ed Hall
decvax!randvax!edhallsaj@iuvax.UUCP (02/15/84)
#R:orca:-57200:iuvax:2000002:000:6353 iuvax!scsg Feb 14 00:06:00 1984 In response to the suggestion that the "Nuclear Winter" effect may be exaggerated, of course it is obvious that we really don't know what the effects of a nuclear war would be--the best we can do is guess. On the other hand, it is also painfully clear that in the past there has been an incredible attempt to display nuclear arms as merely more "big bombs" and totally ignore their potentially devastating environmental and biological effects. In the fifties soldiers were ordered to march right into the vicinity of nuclear tests to see how they would "hold up" under conditions of nuclear warfare. When the Atomic Energy Commission was asked about the effects of fallout they replied that "it wasn't any problem because the radioactive particles would stay in the stratosphere for years." (!!) Only when Japanese fishermen on a fishing vessel passing within about 150 miles of a nuclear test came down with radiation sickness from the fallout showering their vessel did the AEC admit that "oh, perhaps fallout might not stay in the stratosphere forever" (this incident is recounted in "The Closing Circle" by Barry Commoner, as well as other sources) Then there was the supposed "problem" of strontium-90 which the AEC assured Americans was really no problem at all. After all, to be concerned about strontium-90 was obviously some kind of "scare tactic" --as the AEC pointed out, the radiation from strontium-90 can only penetrate 1/2 inch. So it would have to be 1/2 inch away from you to do any harm! Why worry? Well, when biologists discovered that in fact strontium-90 was being passed up the food chain from grass to cow's milk to human bones it would seem that there was some cause for concern after all! The latest discovery of a "Nuclear Winter" effect by two teams of tens of scientists from many fields in BOTH the U.S. and the Soviet Union seems to be falling into the familiar pattern. It has always seemed obvious to me sheerly on a logical and intuitive basis that the environmental effects of the release of millions of times the amounts of radioactivity released by all previous nuclear tests would very likely be enough to destroy , or , at the least, totally disrupt the biosphere. Yet Pentagon estimates of the effects of nuclear war never even seemed to consider the possibility that the simultaneous explosion of nuclear bombs all over the planet might be more devastating than a simple extrapolation from one bomb in one locality. Now the National Academy of Sciences study seems to confirm that reasoning simply on the basis of the debris cast into the atmosphere from several thousand simultaneous nuclear blasts. There are very likely to be other effects of a global nature that are similar that were not considered in this study, and perhaps we cannot even predict. It may be that Prof. Singer is right in saying that the Sagan study overestimated the atmospheric/climactic effects of nuclear war. But I am very skeptical of such a claim. Every time some new danger from nuclear arms has been discovered by scientists, the nuclear partisans have trotted out their own "experts" , like the ones who predicted that fallout would just "stay in the stratosphere forever" and that "strontium-90 is not a problem". I cannot claim to great scientific expertise, but I do know enough about science to understand the "greenhouse effect" and to realize that the "greenhouse effect" which leads to the incredibly hot temperatures on Venus has nothing to do with "particulate matter" like that discussed by the Sagan study but rather to do with excessive amounts of carbon dioxide and other similar gases which allow visible light to pass thru, but reflect the infrared spectrums given off by surface bodies like Venus. The particulate matter postulated by the Sagan study is rather like the dust and soot thrown off by volcanoes and NOT transparent to light as carbon dioxide or ordinary glass is. Prof. Singer's point that the destruction of the ozone layer may not be immediately consequential when ultraviolet radiation would also be blocked by particulate matter is one I had already considered when they announced the study. But his optimism that the ozone layer could be so easily revived contradicts every other scientific report I have ever read on the subject. Moreover Singer cannot have his cake and eat it too- if ultraviolet radiation IS blocked out then so is visible light just as the Sagan study stated. The Sagan study focussed on the possible climactic effects of all the debris thrown into the air by a nuclear war. But there are other effects that may be impossible to estimate as well--what would be the effect on the ocean's plankton of the shower of radioactive material that would follow a nuclear war? What would be the effects on food chains of concentrations of radioactive elements like strontium-90 as these become passed up these food chains in incredibly high doses? What would be the environmental effects of the likely dispersal of plutonium from nuclear plants which would be blown up along with everything else in a nuclear war? It is understandable that many people don't wish to face the reality that nuclear war probably means the extinction of the human species any more than individuals wish to accept the reality of their own death. But I agree with Prof. Singer on one point-we should stop lying to ourselves by talking about "surviving" nuclear war, or mindlessly counting up how many missiles both sides will have left (when there are no people left to defend with them), or talking about "limited nuclear war." For too long we have refused to look this issue straight in the eye-- our own government has deluded us by refusing to admit there even was such a thing as fallout, or then admitting that fallout might be a problem, or admitted that the effects of thousands of nuclear blasts might not be the same as one localized test. The results of the National Academy of Sciences study are not the results of one man-they were checked by many scientists from diverse fields to insure their accuracy. Perhaps they are not totally accurate but it certainly seems prudent to act on the basis of the best facts we have and our own common sense when such a course is a matter of our very survival. tim sevener pur-ee!iuvax!scsg Indiana University, Bloomington
mmt@dciem.UUCP (Martin Taylor) (02/18/84)
Obviously, no-one can prove the nuclear winter hypothesis to be correct
(until it is too late to care), but the analysis seems to be much more
careful than is suggested by the article from orca!danc. In addition,
there was an independent Soviet study that reached the same conclusions,
and I read in the paper last week that a joint US-Soviet study has
reinforced and extended the results.
Someone suggested that the burning of cities was what created the soot
that caused the winter, and that a strike against missile silos would
not cause the nuclear winter. The TTAPS study took several different
cases into account. Their cases 11 and 16 include no urban explosions
(pure counterforce anti-silo missiles). In these cases, the early deep
drop in temperature is less than when there are urban bursts, but the
recovery is long and slow. The scenario is no prettier.
--
Martin Taylor
{allegra,linus,ihnp4,uw-beaver,floyd,ubc-vision}!utzoo!dciem!mmt