My friends think I am unduly pessimistic when I say 100%, — but that projection is for the period of 100 years into the future, and things are not nearly so grim in the short run at any given time. If in the short run we mean this year, then things are quite good, even cheerful, but not hopeful. But, here is some perspective for the longer run: For example, the Chicxulub event that killed off the dinosaurs was 65 million years ago so the likelihood is, very roughly, 1 in 65 million per year. Much more likely is a super volcano like Mt. Toba at 71,000 years ago so I would put the chance at 1 in 71,000. Or about a thousand times as likely as Chicxulub event. Meteor Crater, in Arizona was about 50,000 years ago, and it has been about 65 years since Hiroshima so one might hope that that is a typical rate for those kinds of events. Do you see where I am going with this admittedly simplistic reasoning? Here is a chart for comparison of the potential rate of various potentially powerful events. Notice that this is a rate for a type of event, and not a time between events. Sometimes the events might just happen to be close together, and at other times far apart, but this rate value is an attempt at judging an expected average.
This chart was derived from one at Tulane.edu
Who knows what straight line log log charts really mean when it comes to a subject like this? But, there is a comparative logic which implies that an event such as our current arsenal exploding should happen approximately once in a million years. That is if it were a single item controlled by random natural events. But, if you look at it the other way around there should be a Hiroshima explosion every several decades from a single weapon, and we might be overdue for an event of that magnitude. But, if you look at the arsenal as 30,000 individual bombs, each on their own time scale then the world wide bomb rate gets multiplied by 30,000. There are about 1,000 weeks in a couple of decades so we divide 30,000 by 1,000 and get 30 bombs per week. Well, the bombs aren’t individually deployed, and so it is better to count them on a nation scale, one nation controlling the war event is a better way to appraise them. There are about 10 countries with A-bombs, so we might use that number. In that case we would divide 70 years by 10 decision makers, and get about one event per decade. But the bombs are not equally distributed, most countries having only a few hundred, just enough for deterrence because they didn’t get caught up in a weapons race like the US – USSR. Recently, the only imminent threats have been between India and Pakistan; also there is a growing potential between Israel, and Iran. Viewed in this way the present risk is only 4 combatants. This is a strange calculation which I will come back to! But first let’s think a bit about the more mundane disasters and terrorism.
The real problem, of course, is the 65,000 to 20,000 or so (who’s counting?) hydrogen bombs. The people whom I have talked to, who are in some position of knowing about these weapons, believe that no sane person would use them. To which I answer, “That no sane person would need to build so many — but WE did.” Furthermore, we all have personal friends with occasionally questionable sanity, it is not uncommon, and some person with a short term problem might just be able to do something really stupid. John F. Kennedy seemed like a sane enough person, but he brought us to within an hour of Doomsday before Khrushchev, another seemingly sane person, although the shoe beating incident at the UN was a bit excessively demonstrative, chose to ease off rather than annihilate us all. So when looking at that incident in that way it wasn’t Kennedy, and MacNamara who were the sane ones, but someone totally outside of our supposedly sane political structure who saved us. Back in 1962 there were only a few nations with Atom bombs; now there are many more, and what is to assure us that some person with the power to set off one of these things won’t do it. Perhaps on a lark. On a dare. On a bet. There are all sorts of Failsafe mechanisms in place to prevent such a thing but remember the worrisome movies, Dr. Strangelove, Failsafe and On the Beach which explored the failure issues on screen. Today we are in a much shakier situation than when those movies were made because there are simply more possibilities for things to go wrong, and more people in a position to let them go wrong.
How can the likelihood of these Hydrogen Bombs being used be estimated? First it is necessary to estimate how many different nations have the possibility of deploying the weapons, and their number. This is: US~5,535, Russia~16,000, UK~200, France~350, China~160, India~120, Pakistan~80, North Korea ~10, Israel 200. Hopefully, within each military there must be several persons agreed upon the bombs’ use before they can be deployed, but there may be overrides, and it may be possible for a single person, like the head of state, to activate the process. From the movie Dr. Strangelove, which supposedly annoyed the US Air Force with its accuracy, we see that several people must agree before these things can be deployed, BUT ultimately it is just tripping a trigger like on a mouse trap, and then it all happens rather quickly. These things are so designed that they absolutely cannot go off unless specifically told to do so, and conversely absolutely do go off when they are told to do so. It becomes a tricky procedure to make both arbitrary things absolutely reliable. That times some30,000 bombs controlled, in part, by several individuals in nine or more countries.