Wednesday, June 13, 2018

Climate Change as a Game of Russian Roulette

Ugo Bardi speaks at an event on climate change in Florence, on May 25th, 2018. Obviously, what I am holding is a toy, not a real gun. I was discussing guns as a metaphor for our penchant for doing dangerous things without exactly knowing what we are doing - for instance injecting large amounts of greenhouse gases into the atmosphere. With climate, we are playing a dangerous Russian Roulette game involving the whole of humankind (photo courtesy, Ilaria Perissi). 

In a science fiction story I read years ago, the protagonists live in the future and have forgotten what guns are. Then, someone finds a still working handgun and starts playing with it. As you may imagine, the results are tragic.

Now, let's make a small exercise in epistemology. Suppose that you are one of the characters of that sci-fi story. You have never seen a gun before and you would like to understand what it is and what it does. Basically, there are two ways of approaching the question: the scientific/reductionist way and the Bayesian/evolutionary way. Let me explain these concepts.

The scientific/reductionist way. You dismantle the unknown object and try to build a model of its inner workings. You note the mechanical system that makes a metal hammer hit on the chambers of a spinning drum. One of these chambers contains a brass cylinder partly filled with a mixture of chemicals that you can analyze. You find that the mechanical stress generated by the hammer may ignite the chemicals, producing high-pressure gases which might push an ogival chunk of some 100 g of lead through the front barrel at a speed of the order of 300 m/s. If you align the barrel with a human head, the effects of the chunk of lead passing through the brain would be hard to simulate, but they might involve serious damage. You conclude that it is, most likely, a weapon.

The Bayesian/evolutionary way. You examine the gun and try to build a probability estimate based on empirical tests. You note a small lever at the bottom and proceed to pull it, noting that it generates a clicking sound. You pull it a few more times: nothing happens as long as the hammer doesn't hit the loaded drum chamber (which you don't know about since you didn't dismantle the gun). Then, you conclude that it is probably a musical instrument.

The difference in this approach shows mostly if you use the gun to play the Russian Roulette (*) with one bullet in a six-chambers drum. Then, after five "clicks" the frequentist would tell you, "pull the trigger one more time and you are dead." But the Bayesian would say (**), "since you tried five times and nothing happened, then you are reasonably safe if you try once more."

Of course, these two viewpoints are extreme, there are plenty of intermediate ways to approach a problem, but they indicate how difficult it may be to deal with something unknown. And that's the big, big trouble with climate change. It is gigantic, enormous, complicated, and most likely dangerous. But we are like the characters of the science fiction story of the unknown gun: we have no direct past experience to rely upon. Without disparaging the Bayesian method, surely helpful in many cases, it may be a suicidal approach to use when dealing with something dangerous for which you have insufficient statistical data. That's the case of the Russian Roulette and also of climate change.

There follows the question: do people think Bayesian of Frequentist? It is a controversial subject but, personally, I'd say that it makes sense to say that most people think Bayesian. That may be the reason why humankind has such a cavalier attitude toward the danger of climate change. The statistics we have on climate for the recent past don't tell us anything about the possibility of a true catastrophe. So, we might be tempted use a Bayesian approach to conclude that we have no reason to be worried - and the more time goes by without catastrophes occurring, the more this conclusion seems to be reinforced. After all, haven't we pulled the trigger of this thing you call "gun" already five times? It has to be harmless.

Of course, the scientific/reductionist approach tells us otherwise when the climate system is analyzed and modelized. It tells us that the change may be extremely destructive - actually catastrophic. But that approach seems to be reserved for a small fraction of the population trained in the scientific method. There follows that humankind is playing the Russian roulette with the Earth's climate. And that might well end the way a Russian Roulette game must eventually end.

(*) During the past two decades, the number of suicides in the US has increased by some 25% and the most common method was using firearms. A peculiar form of suicide consists in playing the game of the Russian Roulette. There are no worldwide statistics but 10 years of records in Kentucky alone reveal 24 cases of people who killed themselves in this way. Clearly, it is not a form of mass entertainment, but it does happen. It is hard to say what goes on in the mind of the people who engage in this kind of game, but likely it has to do with the fascination we feel for guns. Nobody knows exactly how many small firearms exist in the world, but the number could be more than half a billion. In the US, there is about one gun per person although, of course, they are not evenly distributed. Some people take guns as true objects of worship and some seem to believe in the existence of a Gun God requiring human sacrifices - that may be the ultimate reason why some people play the Russian Roulette.

From the paper by Lisa Shields. "In one situation, a 22-year-old African American man used a 0.22 caliber revolver in a game with a friend. Each participant pulled the trigger on 2 occasions; the victim discharged the fatal bullet on his third attempt. The decedent was a university student, a member of the varsity football team, and was studying electrical engineering with a 3.0 GPA. Blood and urine toxicology screens yielded no ethanol or other drugs. In another circumstance, a 46-year-old divorced white man employed as a custodian engaged in Russian roulette with his “drinking buddy,” a male friend suffering from cancer. After placing 2 shells in a .38 special, the victim died with the first pull of the trigger. Four of the victims had pulled the trigger at least 3 times before their fatality. A 19-year-old white man significantly increased the likelihood of a Russian roulette fatality. He had a history of depression with a previous commitment at a mental hospital and several previous suicide attempts. Playing a variation of traditional Russian roulette with his brother and 2 friends, the victim placed 5 live rounds in the cylinder, leaving one empty chamber, of a .357 Traus revolver. He spun the cylinder, put the gun to his right temple, and pulled the trigger. <..> The decedent had played Russian roulette on 2 occasions in the previous several weeks, each time placing only one live round in the cylinder." 

(**) A formal statement of Bayes' theorem is:

In the problem of the Russian Roulette, X= you pull the trigger and A= you die

P(A|X) is what we want to estimate: what is the probability that you die when pulling the trigger? P(X|A) is the probability that when you die it is because you pulled the trigger. We may take it as equal to one, neglecting the occasional heart attacks that might strike the player when they pull the trigger on an empty chamber. For the P(A)/P(X) term, we need statistical data but it is obvious that, in a limited number of attempts, as long as the player is alive, the more times they pull the trigger, the larger P(X) becomes and hence P(A|X) becomes smaller. So, you wold be led to conclude that the more times you pull the trigger, the safer you are. Then, of course, for a large number of players (and a large number of deaths), the Bayesian analysis will converge to the reductionist results: n*3.5 attempts are needed in order to kill n people, assuming that the drum contains six chambers and one bullet. The problem is that the Russian Roulette doesn't allow a large number of attempts when played by a single person (or by a single planet in the form of a climate catastrophe).

See also this article on freakonometrics



  1. A minor point. There are far more than 300 million guns in the US. That figure was based on less than twenty years of sales, which are in large part voluntary to report. This does not take into account previous manufacture going back a century, nor those unreported, nor those manufactured at home ( now quite easy-look up "80% receiver" ). I have no idea the political motivation for underreporting these numbers. I for one heartily approve of the concept of there being a possible of up to a billion guns just in private citizens hands. An armed people are not as easily herded into cattle cars.

    1. "An armed people are not as easily herded into cattle cars."

      Only by solidarity can people resist suppression. Most dictators have been brought down by peacefull resistance. A united people needs no weapons. An armed divided people turns on it self.

    2. Do you really think that the US are a united people? We were divided culturally for three centuries. Being armed had nothing to do with it-we were never a homogenous country. NOT being armed when a culturally dived society breaks apart due to resource contraction just means you will become a victim.

    3. I really am very concerned about where the USA will go in the future. In human history, liberty, democracy and freedom where far more often butchered by weapons than defended by weapons.

      The answer to our future problems will not be to retreat into a fortress with guns and ammunition. "Everybody for them selfs" is the continuation of the thinking that got the world into the mess it is today. It will solve nothing and save nobody. But I guess it will be quite some time until this understanding will develop in the USA.

      So no, I think Americans will turn their weapons onto each other, as they allready do. Americans will be each others victims, even more so than you allready are. The right wing authoritarians will come out on top and minorities, (left) intellectuals, progressives and unionised workers will (as always) be the victims and with them all the values america once stood for.

      Having armed militias in the USA was always the privilige of americas far right and white supremacists, and when the Black Panthers tried to arm black people in California in 67, Gouvernor Ronald Reagan was very quick to pass legislations that revoked theire "second amendment rights".

      I observe americas fanatical right wing militias and they remind me of nothing so much as of the SA or Mussolinis "fasci di combattimento". I see Eric Prince, a ruthless assassin and christian right fundamentalist in charge of the worlds largest private army and in league with the ultra rich, ultra right and it fills me with horror.

      This US obsession with firearms may well be the downfall of (what remains of) the american democracy, to think it might "save" america is living in total denial of history and reality.

    4. @ alien observer
      You smell like Igor Panarin :-)

      Lets play just a little with history :-)

      264AC-146AC 3 x Punic Wars

      476DC Falling down of West Rome Empire

      1989 CEE+NATO won the cold war as if Rome won the 2ND barbarian invasion (+2465)

      2030-2050 waiting for Punic War II (+2196)

      if there had been a warfighting chaotic attractor in north america, the next hypotetic American Civil War would have detonated in 4191

      0.5*(2465+2196)+1861=4191 more or less

      I think we need some coke and fried chicken, while we are waiting for 4191DC to control my data!

  2. The first trigging point is the North Pole ice free, it will happen more or less in 2030 and everybody know that.

    This could mean an abrupt slowdown / shot down of the AMOC and/or a bad changing rate of the melting of the methane hydrate bomb in Siberia with positive feedback.

    Passing through those trigging points without doing nothing, it would mean for mankind the probable trigging of many other boiling points on climate change issue, and it will happen many others bad stuffs, that actually Science thinks possible but right now seem unlikely as a rapid vanishing of the Amazon Forest

    At the barbeque of fossil fuels, mankind is playing like a drunk with a Colt M9 fully loaded with 16 rounds on his hand, thinking that it's .45 M1911 with 8 rounds, the firearm whom is in mankind hand. There are 12 years more or less, about of reasonable 8 safe shooting at the empty beer cans, then mankind will find itself in a bad situation of letal crisis in a broad sad violent uncontrollable context, experiencing the natural consequences of all mankind bad decisions taken-"When The Shit Hits The Fan" (sorry for my french slang) it really explain the future mankind troubles.

    The funny fact is mankind collective unconscious already know more or less, what climate change brings, but nobody'e care a lot, simply because the memory of wars are far and all mankind never ever have handle what the hell will happen, except into some Videogame FPS, but those scenarios look unlikely.

    IMHO the main responsability are for politics, politics are stupid and thiefs: big responsabilities mean big errors, big flames. No doubt about that.

  3. Hi Ugo,

    I think I don't agree with your description of what the statistics mean.

    As I understand it, the main difference between frequentist and Bayesian stats is that Bayesian stats are codified to include new information. In both, the prior (knowledge of what is likely before any data are collected) is vital to obtaining a meaningful result.

    In your example, I think you are conflating frequentist stats with reductionism (taking the gun apart to understand its working), and Bayesian stats with experimentalism (testing the gun).

    One could equally argue that the Bayesian scientist could disassemble the gun and realise that on the 6th pull of the trigger, a different event would occur and that danger was imminent (in Bayesian terms, this would be the 'prior').

    Still, I think your post is commenting on something important: what prior knowledge should we incorporate into our statistical models? I think this is what climate change (and eco-collapse) disagreements are all about.

    Cheers, Angus

    1. That's correct. I said in my text that I was taking an extreme way of describing the situation. You may very well think of intermediate situations and, yes, the prior could be knowing that there is a bullet in one of the drum chambers. But there are cases in Bayesian statistics where you don't have data to determine a prior - in that case it must be guessed out of thin air - which I think is the relevant case in the example I was making.

  4. There are many of us who have nearly given up thinking about the vastly larger number who are piling up the (AGW) trigger pulls at a great rate. How many more trigger pulls result in how many shattered heads.. ?
    I don't know even vaguely how many, like me, have even given up worrying about my own trigger pulls. I am going to take a plane trip.. learn a few new languages.. no particular point.. just still alive amongst you..

  5. The question scientists have not been asking in my mind is: why does evolution proceed in a Bayesian and not scientific manner (I would love to read theoretical modeling on it if there is any)? Is it just not possible due to some kind of physical constraints or is it not competitive? Say we find a gun all people alive have forgotten how to use in the future, what are the cost associated with the Bayesian model (1 life) versus the cost of a scientific model (unknown but I suspect insanely high). Fossil fuels are the heart of science in my estimation. Scientists now recognize we must rip out its heart. Maybe a heart transplant is possible....maybe not.

  6. when italians will see our first Mediterranean mini-uragan blasting a costal city?

    I don't know, but I guess before 2030

  7. I think you might misunderstand probability. There are 100 people and 1 gun. One person pulls the trigger N times and dies. The remaining 99 people conclude the gun is a weapon and treat as such thereafter.

    1. Well, you can see it in this way. But my point was another one. You have 7 billion people and one planet . . . They play the climate change game and everyone dies.

    2. Climate Change is not "chicken game" at negative sum, just like the "cold war Warsaw Treaty vs NATO" issue.

      In Market Economy, inside a different scale of economic dimension, there are always games at sum positive until you reach your own market saturation. When you reach the top of the logistic function then players changes games, and everybody start playing games at zero sum (fusion, acquisition, bankrupt are stuffs to enlarge or killing your ecoonomic enemy, to enlarge your own market share and get bigger and stronger than other remaining competitors. That's why we say Markets tend in the long run to slight to Oligopoly/Monopoly, and why States have to regolate those stuffs to protect consumers)

      Same thing in International Competitive Market, but there is a big difference.
      No Earth Istitution protects the more fragile players, infact ONU never ever financed a demographic policy control in Africa (as China and India did in their own country) and Catholic Church never ever asked a demographic policy control for Africa (even Catholic Church has always know what was the real situation on the ground, from catholic missionaries) even the limits to growth was published in 1970s (quite in time, for stopping African Demographic bomb).

      There are 3 worlds in different state of developt: I°countries have saturated markets with low rate of growth = low interest rate (do not consider the problem of sovran debt for the moment and the issue of bankrupt risks) and II°,III°countries have not saturated market with high potential rate of growth = high interest rate.

      This means, there are a lot of opportunities for making profit and developing poor countries, but the issue of overpopulation and climate change (made by mankind on using fossill fuels paradigm) in the long run, it is stopping this economic game, because Earth changes its climate, as if planet is getting smaller.

      When Earth gets smaller, less people can survive on this planet, then I°countries and II°countries have "know how" and capital and military hard power to understand what is going on in the Earth, menawhile III°world even doesn't know what the hell is a zero sum game.

      It seems to me quite simple: as Clausewiths said:"the war is the continuation of politics by other means" and to understand future, it is necessary to enter into che military dimension:

      III°world will get trapped and used by I°,II°countries for their objectives, and I°world will fight versus II°world.

      Military-Politic coalitions will form on following Latitudes ratios (nations in same Latitude have same problems, versus Nations in different Latitude with less problems).

      Different nations in different state of developt, with different hard power, all this variety of initial conditions will produce an Aggressors coalition versus a Defender Coalition (more or less dense)

      DIVIDI ET IMPERA strategy will be the attempt of the Aggressors coalition over the Defender coalition.

      I'm waiting historic facts to control my theory, and for the moment the Early Warning Signals are confirming all, for the rest there's only to wait and see...

  8. Bayesian/elolutionary way was used by early humans. That's how they found out which herbs are edible, which have medicinal properties and which are poisonous. Many early humans died to gain that knowledge.

    Several years ago I saw a cat in my father's village that used Bayesian/evolutionary heuristic method. The cat saw salamander and was curious what could that be. The cat was reluctant to eat that strange slow moving animal. After 30 minutes I saw cat dying in horrible pain. The cat obviously decided to try a new meal. That was cat's last meal. The cat decided to disregard the warning sign on salamander: black and yellow color, the sign that means "do not eat". Salamander has glands that secret poison in his skin.

    We are like the cat described. Like any knowledge, scientific knowledge can be lost. For instance, due to demise of civilization. Those who survive risky experiment with CO2 emissions will have to use Bayesian method all over again.



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)