Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Friday, January 18, 2019

What are the chances of a war that would exterminate most of humankind? It could be more likely than you think

Recently, together with my coworkers, I have been engaged in a statistical analysis of war over the past 600 years. The results were sobering: war, it seems, is a statistical phenomenon similar to earthquakes and forest fires. It strikes according to well defined statistical patterns and there is very little that can be done to avoid it. Aaron Clauset is another scientist who has been working on the same subject and, in a sobering analysis of his, he calculates the probablities of future wars. According to his calculations, a war as large as the Second World War has more than 40% chances to occur within 100 years from now. Then, a war causing more than billion battle deaths, that is exterminating most of humankind, has a probability of 5% to occur in less than 4 centuries from now. That doesn't mean we can relax for 4 centuries, not at all. It means we can expect it at any moment in the future.

From Aaron Clauset, 2018. (highlighting by UB)

.... a stationary model may be used to estimate the likelihood of a very large war occurring over 100 years, one like the Second World War, which produced x* = 16,634,907 battle deaths. Using the ensemble of semiparametric models for the sizes of wars and assuming a new war onset every 1.91 years on average (43), the probability of observing at least one war with x* or more deaths is p* = 0.43 ± 0.01 (Monte Carlo), and the expected number of these events over the next 100 years is 0.62 ± 0.01. Hence, under stationarity, the likelihood of a very large war over the next 100 years is not particularly small.

Under an even stronger assumption of stationarity, the model can estimate the waiting time for a war of truly spectacular size, such as one with x = 1,000,000,000 (one billion) battle deaths. A conflict this large would be globally catastrophic and would likely mark the end of modern civilization. It is also not outside the realm of possibility, if current nuclear weapons were used widely.

Using the ensemble of semiparametric models of war sizes and a longer Monte Carlo simulation, the model estimates that the median forecasted waiting time for such an event is 1339 years. Reflecting the large fluctuations that are natural under the empirical war size distribution, the distribution of waiting times for such a catastrophic event is enormously variable, with the 5 to 95% quantiles ranging from 383 to 11,489 years. A median delay of roughly 1300 years does not seem like a long time to wait for an event this enormous in magnitude, and humans have been waging war on each other, in one way or another, for substantially longer than that.


  1. Aside from nuclear weapons, even relatively small or localized wars are capable of causing unattended spent fuels to boil over, leading to ... yet more problems.

  2. Or perhaps we might see it at a different time scale - where instead of seconds, it is decades - we are in a suicidal war that is just as violent, with all the heat and combustion and all victims will be a direct casualty - by human hands. The only differences are the weapons chosen and the plunder extracted, the outcome is the same.

  3. Ugo, I don't know what's happening with your posts at the moment. When I open a new post and start reading, it suddenly jumps down to the post about the Doomstead Diner poll and I have to scroll back up to the current post. It's very annoying.

    1. Yes, I have the same problem. I'll do something about that, asap.

  4. No need to wait a thousand years for a deadly war to reduce our population. Natural cause of events will do that in the next hundred as we burst the limits of our planet.

  5. I'm sorry, I don't agree a single word about the bad research named "Trends and fluctuations in the severity of interstate wars"

    because of

  6. The notion that future wars are possibility is a given. The methodology of trying to give it a statistical probability that has any predictive meaning is utter nonsense, even more meaningless that predicting the direction of an algorithmic driven stock market. Ugo, please use more discretion in posting on one of the best blogs on the internet.

  7. But, but Stephen Pinker????? I'm kidding

  8. I disagree with that opinion. First... history is not linear, so we must be very cautious when we make trends into the future.
    Second... most wars don't make a very huge damage on growth population numbers. That is because most direct death are from males, and a void of people makes a lot more probable to a rebound of population after the war.
    Normally we make doom predictions over the hypothesis of catastrophic side effects on nuclear or biological weapons. Something that we NEVER experience, so we don't really knows how it could happen.
    Nuclear weapons could be a blink into humankind history. It could be near banned in the future. If the nuclear fission reactors dissappear, make a nuclear weapon program will be very complex (mostly would require to build that reactors only for that purpose).

    But we could even exagerating the consecuences of a nuclear war. We could be overstimating the impact of that radiation on people that could adapt to live into more cleaner areas and avoid worst effects with some detectors.
    Most deathly radiation will drop "fast".

    The worst probably scene will imply a nuclear winter but it's not clear that we could generate so much huge effect to affect all humankind. We have learned how to insulate heat well and geothermal spots could create some safe spaces.
    If the nuclear winter not turn so huge to create a small snow ball effect, there would be enough microclimates on ecuator to survive millions.

    I'm doubt that we could become extint though a war even on a nuclear war scenario.

  9. @ Zanstel January 21, 2019 at 3:16 AM

    I suggest a couple of things:

    1-Please, do not confuse nuclear tactics warheads with strategic nuclear warheads!, those are quite different stuffs!

    2-Nuclear tactic warheads usually are stuffs like one fission bomb dropped via airplane or via cruise missile. The nuke always has a power detonation less then 150kilotons each ones. The range of use for a tactic warhead is short, with a variable power detonation to 20kilotons until 150kilotons.

    3-Strategic nuclear warheads are quite different stuffs: those warheads are fission bomb and fusion bomb also. Those warheads are on board on ICBM and SLBM and bombs for long range bomber. All modern missiles have MARV/MIRV so one single missile usually brings 10 MIRV with 150kilotons warhead each, so it's a power of 1.5Megatons for each missile!. Old ICBM don't have MARV/MIRV so they bring one single very big warhead, as many big bombs are for long range bombers. The power detonation is apocaliptic! those stuffs can reach even 20Megatons each warhead!

    3.Keep in mind: the two nukes on Hiroshima and Nagasaki had 22kilotons only!

    Modern nuclear tactics warheads have a big punch: but a nation can survive at one nuclear tactic detonation!

    Nuclear strategic warheads are the righ hand of satan: one ICBM/SLBM, long range bomber bring from 1.5Megatons until 20Megatons, it depends of what kind of warhead it has on board.

    4-Nuclear War into cold war has been studied a lot, I suggest to read this magnificent book!

    5-In few words:
    Mankind can survive at one, or many short nuclear wars, if war actors drop a few number of tactic nuclear warheads only.

    Mankind can't survive into a strategic nuclear war, because in this case each war actor would use to the enemy a massive pre-emptive nuclear attack or a double punch!. double nuclear punch is:

    first punch: ICBM+SLBM
    it is a massive pre-emptive attack or
    a massive launch for defence purpouse before enemy warheads would punch:

    second punch: after the first nuclear punch the air defence are down so, if it is necessary a counter-strike
    air nuclear bombing+SLBM are the stuff to use for.

    In this case, in any case, a nuclear winter would cover the earth, on spreading out all the nuclear fall out on earth.
    Six, may be one year, then all life on earth would be dead.
    End of the story of all mankind and all life on earth.
    Beatles rule the Earth.



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)