Nuclear Winter and Other Pseudoscientific Fantasies
Sagan and the group who proposed Nuclear Winter originally posited that an exchange as small as 100 MT would result in a years-long global winter brought about by smoke from burning cities. This “theory” was last updated in 2007; now the main fear is that an exchange of an aggregate yield as little as 1 MT (50 20 KT weapons) between India & Pakistan would cause a global-size ozone hole leading to climate change, environmental damage, human health problems, etc.
The Earth has already had two such 100 MT events and we saw no nuclear winter, no global ozone hole. The Soviet test series from 1 Sep 1961–4 Nov 1961 and 5 Aug 1962-25 Dec 1962 certainly saw over 100 MT each time. In the first series, weapons of 58 and 25 MT were detonated a week apart; they were just two of 50 atmospheric shots; 12 others were in the MT range and dozens of KT range detonations. The second series had two 30+ MT detonations, a 20 MT, a dozen other MT range and two dozen KT range detonations.
During this latter period, the US fired 9 weapons in the Pacific. Two of there were MT range; 3 in the high KT/subMT range and four in the lower KT range, all either exploded in the atmosphere or high altitude bursts (which would maximize ozone depletion). These tests are all listed in Glasstone’s The Effects of Nuclear Weapons. Sagan then and others now ignore these facts; either of these tests series were well above the threshold they set for global catastrophe yet none happened.
The closest events we can come to nuclear winter or nuclear autumn was the Krakatoa volcanic explosion of 1883. Five cubic miles of earth was ejected into the atmosphere which did affect the weather for a year or so. Even with exclusive use of ground bursts, you would have a hard time ejecting 5 cu miles of soil into the atmosphere if all the world’s nuclear arsenals of today were used at once (you probably could have dome in the late 70s or early 80s when there were more & larger yield weapons but not today).
Other examples such as the fire bombings of Dresden, Tokyo and others in WWII can’t come close. Once the fires went out, the smoke dispersed with no damage to the climate. Mount Pinatubo in 1991 ejected less than half the amount of solid material as Krakatoa and most of that was magma, not earth. Pinatubo did inject huge amounts of SO2 into the atmosphere; I read that it put more “industrial gasses” into the air than all the industry on earth since the start of the Industrial Age. And, no nuclear winter, no climate change. What all these theories of global destruction fail to account for is the ability of the Earth to cleanse itself. There are natural processes which purge the air of contaminants.
The movie On the Beach told of the destruction of life on earth by nuclear fallout which swept the Earth. That is pure poetic license; the radioactive fallout produced by a nuclear detonation, asdestructive as it is, follows the laws of physics. Fallout radiation decays with time; the protective principles of Time, Distance and Shielding are effective measures for people anywhere. In the movie, fallout acted like a gas that spread everywhere (even crossing the Equator!), never diminishing in strength nor diluted in effect by distance or spreading into a larger volume. It was good theater, but bad science.
When the government surveyed buildings to identify Fallout Shelters, they were very conservative. PF = “Protection Factor” refers to the ratio between the radiation dose rate of the OUTSIDE to that INSIDE the shelter, for instance a PF = 10 (provided by about 12 inches of earth or 8 inches of concrete) means that the inside dose rate is 1/10th the outside rate. A Shelter with a Protection Factor of 10 probably has an actual PF of 40 or more. In other words, the attenuation of fallout strength inside a shelter is probably at least 4 times the stated reduction.
Based on the 1984 study, "Health Physics Aspects of Nuclear War", by the Health Physics Society, the following factors increase the Protection Factor, PF, of fallout shelters against fallout radiation:
1. The original formulas to determine Protection Factors are very conservative and hence underestimated PFs. The formulas were calculated using a single radioisotope, Cobalt 60, a "hard", high energy, gamma emitter. Actual fallout consists of over 200 isotopes of 60 elements, much of it "soft", low energy, gamma radiation with less penetration. Increase in PF: up to 2x; applies to all shelters.
2. The original PF calculations assumed the earth is a perfectly smooth, infinite plane (i.e., a billiard ball) that reflected radiation and did not absorb it. In reality, the earth's surface is rough and absorbs or scatters radiation.
Increase in PF: up to 2x; applies to all shelters.
3. The original PF's were calculated for empty buildings. "Mutual shielding" is gained from contents and by tightly packing the people. Increase in PF: 1.5 to 3x
4. The original PF calculations assumed no shielding from blast debris. Such debris, if present, contributes to shielding. Increase in PF: 3 to 10x
5. Fallout was assumed to be uniformly distributed with the same rate everywhere. In reality, wind & eddy currents will drift fallout into non-uniform patterns. Rain will remove fallout and channel in into storm sewers, etc. Increase in PF: add to PF: 2 to 10 for wind alone plus up to 100 for rain; applies to all shelters.
6. The original PF calculations were for an individual, isolated building. In reality, adjacent or nearby buildings, landscaping, decorative walls, etc. increase the PF. Increase in PF: 2 to 3x.
Therefore, in the real world, a fallout shelter with a calculated PF of 10 would, depending on the factors listed above, have an actual PF of from 20 to 40 which would greatly reduce the radiation exposure of people inside the shelter. For example, if the total exposure outdoors is 3000 R, a PF of 10 reduces it to 300 R. A PF of 20 reduces it to 150 R and a PF of 40 to 75 R.
The greatest hazard from a detonations remains the blast/heat affecting the area around the detonation; fallout radiation downwind and EMP.
Effects of 10KT NuDet (ground burst):
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1/3 mile from epicenter all buildings are destroyed, virtually no one left alive
3/4 mile radius major damage, most people not in substantial shelter killed or injured
1 mile radius moderate damage, buildings ravaged by fires and many blast survivors will die later from lethal radiation exposure
Downwind debris plume further exposes tens of thousands to lethal radiation dose unless survivors are adequately sheltered and effectively decontaminated
Of the three, the effects of EMP have the potential for causing the most misery and perhaps death. If EMP shuts down the electrical grid for a few weeks or more, a substantial portion of those people who are “fragile” or vulnerable in terms of health or nutrition or who simply are ignorant and unprepared will die because they can’t get what they need to live.
A substantial portion of those injured in the attack will die if the medical system is overwhelmed or compromised (e.g. by EMP or inability to move patients or resupply hospitals). Most people will live but they will need purposeful leadership (which is distinctly lacking). Society will be fragmented in direct proportion to the inability of local, state and the federal governments to redirect people from “normal” living through survival mode and back to reconstitution of society.
The better organized and prepared a society is, the fewer deaths, less misery and less economic/societal disruptions will occur. We’re a long way from there and, from a global geopolitical perspective, there are other several nations whose purpose is to make sure we never arrive.
If I remember my history correctly the winter of 1944/45 was the worst on record.
I remember the summer about 6 or 7 years ago where fires in Mexico lowered the temps here in Texas by 5 to 10 degrees. Smoke everywhere from agricultural fires 1200 miles away.
You are right that we will not have a winter type climate in the summer. I do believe that if could be disasterous if it happened during planting and we had late late frost.
while the amount/exploding placement of mega-tonnage does factor into the equation, it is possible to end human life on earth via exploding enough bombs over a wide geographical area. The point being the totality will overwhelm the atmosphere.
Note that America's atom tests in the Pacific including the Big Mike test
very most often on deserted islands with much of the blast going out over water as opposed to urban areas. The same can be said for the Nevada tests when it comes to urban areas.
You may have read about the now declassified doomsday bomb. Without even considering destruction to urban areas it is possible to create enough residual radiation with a cobalt-25 device to end human life on earth. Translation - during the cold war the Red Army would never march down Pennsylvania Avenue and the 101st Airborne would never march through Red Square. This, it has been learned, was one the secrets behind Kennedy's statement of MAD (mutually assured destruction).
It is interesting to note that the now declassified writings of Nikita Kruschev reveal that when he came to power in Russia and learned of the real potential of nuclear war Kruschev could not sleep for three days. Then he realized neither side could have nuclear war so he once again resumed sleeping. Interestingly, he ordered the Soviet Union not to get into a nuclear race with the West. Kruschev took to the policy of having only enough nuclear power to keep the West fearful and keep the West pouring resources into atomic weapons it could not use. The size of the West's nuclear arsenal was on no consequence in Russian policy making.
nathangdad - you can choose to believe what you want. It is not supported by the science. You folks may carry on and I will be entertained. I won't discuss this any further. Instead I will wait for President Obama to tell the truth about the space aliens living among us and how the aliens gift technology to provide unlimited free energy will save us all.
I had no idea how cool AM radio was until we started bringing a radio camping. Tell you what, at 7500 ft, the signal is clear as day at about 9pm... something about atmospheric blither blather working in our favor.
Nuclear Winter is not an issue for me, I am putting my money on water rationing wars or starvation. Hell, China could cover us with Radioactive dust without even leaving their borders, ever seen the views of the Gobi desert sand working it's way to N. America?
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I take my coffee how I take my women: bitter and overbearing.
Nuclear Winter and Other Pseudoscientific Fantasies 
