Game Theory Shows The Way To Control Climate Change
    By Catarina Amorim | October 10th 2013 06:17 AM | 22 comments | Print | E-mail | Track Comments
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    After many years as a scientist (immunology) at Oxford University I moved into scientific journalism and public understanding of science. I am...

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    A week ago, the UN Intergovernmental Panel on Climate Change (IPCC) delivered to massive media coverage an unsettling message – climate change is real, humans are the main cause of it, and unless we stop the warming of the planet, in 50 years life as we know will be no more. The problem now, is that despite in numerous attempts, world consensus on how to do it has proved impossible.

    Research in Nature Climate Change by a Portuguese team known worldwide for their studies on cooperation claims to have not only identified the root of the problem but also its solution.

    Vítor Vasconcelos, Francisco Santos and Jorge M. Pacheco from the ATP-group at Lisbon used game theory – a branch of mathematics that studies human social interactions – to look into the problem, and found that the key was “scale”. Their work showed that cooperation for climate control will only be possible if approached at regional or domestic level, with local institutions sanctioning those that do not collaborate (free-riders).

    But not just that, as Pacheco, the team leader explains “ Our most striking result was to find that punishment by global institutions – which at the present situation would be the most logical choice – is almost like applying no punishment. “ The data supports what many believe: that polycentric governance (with many centers of authority) is more effective solving global problems than a central international authority.

    The findings calls for an urgent revision of the current approaches to climate agreements, and could have not come at a more relevant time with the IPCC now reunited to decide on measures to reach climate change mitigation.

    So why are we experiencing global warming?

    Despite the media space given to “climate change deniers”, there is an overwhelming scientific consensus that the major cause of global warming is an increase of greenhouse gases (such as carbon dioxide and methane) from human action, such as fossil fuel burning, expansion of landfills sites, deforestation, etc. This because earth’s temperatures result from, not only the incoming sun energy, but also the “greenhouse effect” (where heat released by earth is absorbed and sent back to the surface by the greenhouse gases in the atmosphere). So as the quantity of greenhouse gases increase by human action, so the heat absorbed and radiated back to earth, and also global temperatures.

    Once this became clear, environmentalists everywhere started asking for a control of greenhouse emissions and in 1998, the Kyoto Protocol, which establishes targets to reduce greenhouse emissions, brought some hope that this could be possible. But 18 meetings and 192 countries’ signatures later, still only a handful of nations are following its directives. A clear obstacle is the fact that the risk of climate catastrophe is (wrongly) perceived as low, since it is far in the future. 

     So how to “force” the world towards climate control?

    It is now believed that the solution has to be an effective sanctioning/punishing system, capable of deterring those that contemplate escaping their climate control obligations.

    In the study now published the researchers use game theory, which not only models human strategic interactions, but can also predict the best conditions for a behaviour to emerge (like cooperation towards climate control), to test different types of sanctioning.

    In 2011, Pacheco’s group had already demonstrated using game theory that current approaches – global summits where countries meet in one single group to try achieving an agreement on climate change – were actually detrimental for cooperation.

    In the new work they look into using instead local institutions to promote a climate agreement, and test how different types of sanctioning could influence the outcome

     So how does game theory work?

    The idea is to design a series of mathematical equations that represent the strategic game we want to test. In this case we have a public good game, where the “public good” (a global good from which everyone benefits, whether they contribute for it or not) is the welfare of the planet, and the aim is to find the conditions necessary to make the players cooperate protecting the planet. A catch is that cooperation in here is not to gain something, but to avoid the risk of collective loss (catastrophic climate change) what makes an agreement harder to achieve.

    There also two extra obstacles: first the fact that players see the risk of climate disaster as low, and second that the game only has a positive outcome if most players curb enough emissions otherwise everyone will lose. And the problem is that nobody knows what others will do, so it is not clear how much is enough. This, together with cooperation implying sacrifices, makes the chances of free-riders appear very high (like the Kyoto agreement’s results so well demonstrate).

    Like in any game, there are players and they can be either be co-operators (C) or defectors/non-co-operators (D), but since the Portuguese wanted to test the effect of sanctioning, they added punishers (or P), who are co-operators that contribute also for a sanctioning institution. Like in real life, the players can adapt their behaviour (from being a C to a D for example), as they see what others are doing.

    If you do not want to know about the maths behind the findings look away now (and go to “Results”)

    Once a model that included all these conditions was put in place, Vasconcelos and colleagues started by calculating the population’s Stationary Composition - which gives the population most likely set of behaviours (C, P and D), by finding the length of time each different combination of C/D/P lasts (for example how long for 40% Cooperators+40%Punishers+20% Defectors).

    From this, they can find Institutions Prevalence - the time a sanctioning institution lasts, and, most importantly, Group Achievement, which gives the number of groups that cooperate, or, basically, how successful (or not) the cooperation is

    Then, to identify the best conditions to achieve cooperation, the researchers investigated how these 3 parameters (and especially group achievement) vary with different conditions, in particular , different levels of risk perception in 3 situations: when there is no sanctioning of free-riders, when the sanctioning is being done by a global institution and when is done, instead, by several local institutions.



    The Portuguese researchers team's results showed that cooperation grows with risk perception. Since in climate change the risk is perceived as low, no surprise that a global agreement has not been achieved.

     The good news is that this dynamic changes radically once sanctioning by local institutions is introduced. In this case, cooperation is possible even when the risk is seen as low. Surprisingly, punishment by a global institution gives a pattern of cooperation similar to that found if there is no sanctioning (which is directly dependent of risk size).

    This last result is particularly important because it is not an intuitive one (a global sanctioning institution is as effective as do nothing?) and chances are that the IPCC, in its next report in April, will recommend global sanctions mediated by a central international institution, which, according to these results, will not work.

    So why are local institutions so much more efficient cooperating even at low risk perception? Vasconcelo’s study were able to identify a variety of reasons – for a start local sanctioning institutions tend to last longer (promoting cooperation) than global ones, and are easier to emerge acting as catalysers of collective action while stopping free-riders.

    The frequency that the individuals change behaviour (from cooperating to become free-riders for example), and which the researchers show to increase the chance of cooperation, is also higher in local institutions probably because these have shorter-term goals allowing players to reassess their choices frequently.

    Finally their work also shows that there has to be a minimum number/percentage of punishers (co-operators that contribute to the sanctioning institution) to trigger cooperation in a population, and with many local groups (instead of a global one) there is a bigger chance that at least some will manage it (after all in smaller populations a smaller number of punishers will be needed).

    Vasconcelos and Pacheco’s new work crucially supports what the Economics Nobel prize Elinor "Lin" Ostrom first proposed- that the resolution of climate change lies in polycentric governance; a governance coordinated at many different levels being more effective than an international “top-down” approach (like the one we now have). 

    It is easy to understand why - if climate change has different effects at multiple levels and regions, governance by the groups directly affected has to have the higher chance of success.

    And there are already a few successful examples - one of the best-known is the launch, in the 70s, by several US local governments of measures to reduce air pollution (including greenhouse gases). A 2001 study of 51 of their metropolitan areas showed that, in under 20 years, air pollution was diminished by a third.  Other successful example is a program, in Berkley California, that subsidizes the installation of solar panels in homes and businesses and that has been hugely successful.

     As Pacheco so perfectly summarizes: “Climate control?  Think globally, act locally” 


    Vítor V. Vasconcelos Francisco C. Santos and Jorge M. Pacheco,  A bottom-up institutional approach to cooperative governance of risky commons Nature Climate Change 3, 797–801 (September 2013) doi:10.1038/nclimate1927  


    Science20 could gracefully back off of it's shameful support of the CO2 exaggeration by demanding that science give us a real warning for a real crisis because 30 years of just "could be" from science proves it "won't be" a crisis.

    'Mememine' is a well known astro-turfer for the denial industry.
    He spams the same off topic gish gallops of the most absurd nonsense to any and every publication and blog that includes the word "climate" in the header.

    He posts to about 40 threads under around 5 or 6 different screen-names and his total number of spam posts under the sceen-name 'mememne69' alone is nearly 10,000.
    His real name is Paul Merrifield and he is an obese 60 year old loser from Niagra Falls now living in London, Ontario.
    It has been explained to him a hundred times that the scientific method deals in the balance of probabilities and not absolutes. He usualy just does a 'drive-by' posting and doesn't even attempt to refute the proof that he is posting BS.

    I always report him as spam whenever possible.

    He often changes his name but he is instantly recognisable from the same old posts week in week out.

    Just shows what intelligent people are up against when there exist repulsive individuals who are prepared to threaten ours and our childrens future for his ideological beliefs and whatever pennies the carbon corporations toss to him.

    Your physician cannot tell you cigarettes will cause you to die of cancer. All s/he can say is that they dramatically increase your odds of developing lung, oral, oesophageal, gastric, colon, and skin cancer, will almost certainly shorten your lifespan, and are 50% likely to be the direct cause of your death. Scientists at the IPCC, having reviewed all the science of the past ~4 decades, are >95% certain global warming is largely human caused, and is a bad thing. We ignore science, like we ignore our physicians, at everyone's peril.

    BTW, mememmine69 is a spamming, astroturfing sockpuppet troll. He's also known as Al Bore, David Nutzuki, Rachel Carson, mememine, Paul Merrifield (various spellings, and possibly his real name), Dizzy May, Mother Nature, Jack Frost Burrr!!, and so forth. Plus, he's boring.

    As a practical scientist, I feel that this article crosses a boundary that I won't step over. Any discussion of establishing "punishers" to control our behavior is quite disturbing.


    Brian unless you give in an anarchic utopia there is no way you can avoid "punishers" from your mother to the parking attendant
    Interesting perspective. However, I do not believe punishment will work. At best it must be combined with more explicit rewards for correct behavior. Then you have the fact that the solution is not tied to just reducing emissions for instance. Just like with climate models themselves, this model of society - the game approach - is also a simplified version of reality. So.

    All the same, very interesting article. I enjoyed reading it.
    Bente Lilja Bye is the author of Lilja - A bouquet of stories about the Earth

    It can only be  a simplified model Bente, for a start game theory can only make predictions when the players act rationally what we know in humans is not always the rule  … But the work's idea is not so much that that punishment is the final answer  but that 1- there is a need for effective punishment to improve the chances of cooperation and 2- but this will only work at t locally/regional level anyway. And at this level,  things  will be different at other aspects - you expect  kin selection to have an effect (when altruistic behaviour appear towards these close to us) for example. 
    It will remain a theory no matter how much effort is put for its realization, it will not be enough to control the general public into compelling into cooperation. Maybe, for a while but not long. As long as there are people the tendency will always be towards disorder. Reduction of population is the best solution to it.

    Very good point Bente,I observed during my first attempts at fatherhood that the more i tried to control my son[for his good i thought]the more naughty he became,until i had to settle on a few most important rules and let the lesser ones go.The positive love i had for him was the most important ingredient..Whereas not to negate the importance of punishment and this blog love is still the best way and i don't know whether that"s scientific but i''m sure It's universally recognised,even if it's sometimes hard to practice.

    "...and unless we stop the warming of the planet, in 50 years life as we know will be no more."

    I have family published in in climate modeling that travel the world lecturing and I have never heard them suggest that in 50 years life as we know will be no more. I'm slogging through the actual scientific summary of AR5 and have not yet seen any such claim there yet. Do you have a scientific source to support your claim and in what form it will occur?


    The idea behind this comment is that is if we continue at the same  rate of global warming as now, the prediction is that  in 50 years we should be at least 2 degrees above what we have now, and this will mean  totally different ecosystems. A good example was what just happened r in the south of europe  at the beginning of the summer,  a heat wave from the north of Africa resulted in the overgrow of usually rare bacteria in the sea provoking skin reactions that led to the beaches having to be closed for periods. It's easy to imagine the scale of what could happen if we go 2 degrees above what we have now for good.  
    Bonny Bonobo alias Brat
    A good example was what just happened r in the south of europe  at the beginning of the summer,  a heat wave from the north of Africa resulted in the overgrow of usually rare bacteria in the sea provoking skin reactions that led to the beaches having to be closed for periods.
    Catarina, do you have any links to articles describing these bacterial outbreaks in South Europe in more detail please? I'm having difficult locating them. Which countries, what sort of bacterial outbreaks and which months would be good if you have them?
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at

    It was in Portugal and this summer,  I don't think there is any publications or if it will be as 1- the skin-reaction agent was a  normal part of the sea fauna and 2-  the news fazed out when it was discovered that was not a toxic contamination although the reports of allergy-like skin reactions continued.  
    Lies and deceit in order to get your well documented false leftist authoritarian liberal agenda pushed through, the gamesmanship is already its happening all around us, the largest gammer in the AGW debate is the IPCC.

    Really Hank, you allow this dribble to be posted on a supposedly scientific web site? Perhaps you should think about renaming it to something more fitting, like Pseudoscience2.0.

    Dear Dr. Amorim, how do you explain 15 -- by some counts, 17 -- years of no increase in global mean temperature, contrary to the prediction of nearly all the computer models?

    How about you and your colleagues stop ringing the alarm bells for a while and devote yourselves to gaining a better understanding of climate?

    Take your time, there is no rush.

    Obviously the only course is to reduce the no. of people producing CO2. The best way to choose who would be by their usefulness to society and the human race. I think this author/journalist would qualify for a needed CO2 reduction scheme. Perhaps we could have them transport themselves to salt domes and we could sequester their carbon there.

    Why does an (immunology/autoimmunity) person think their opinion matters more than an ants does on this subject?

    ha ha ... ouch.

    Of course, why would an immunologist not understand basic science better than an ant? Or an anonymous commenter on the Internet? If we are culling people, should we start with people who make pointless comments that contribute nothing to the science or the policy issue?
    Maybe as an engineer I should consider my opinion on immunology worthy of writing policy articles on drug resistance and immunization? Pushing a policy punishing people for non conformance to an hypothesis that has not been proven (for which the author has zero education or experience in accessing) and possibly can't be proven has to be a non existent standard of science and... and dare I say policy making. Maybe we should bring back reading bumps on people's heads for admission to universities?

    Yet as an engineer you feel qualified to claim expertise on climate science. It doesn't compute. If she can't understand and provide an overview of this issue, neither can you - nor can any science journalist. Nor can any physicist, including James Hansen. 'It is not your PhD' is a cop out to avoid the issue.

    Dear anonymous12,  as you might know (or not…) science is never a finished process,  we learn more and more as we research, but we can nevertheless take conclusions based on the evidence we have, supported by a mathematical process you might know and believe (or maybe not) called statistics. So on the questions you ask me, I would advise you to read the IPCC report , and if you can't be bothered  to do that I am even adding a link to a synopsis of it done by someone involved in climate studies for many years (what might help you believe .or maybe not..) from the US, which, in a not very wild guess, I presume is where you come from 
    Dr. Amorim I agree with your advice to anonymous12 and I am reading the actual scientific assessment from the IPCC AR5 WG1. I understand your concerns about the potential harm to ecosystems but many of these changes will occur from regional and local warming and much of the impact will be caused by local land use change. There are also regions that will benefit from a warmer climate according to the report. But also note that IPCC AR5 is not the latest on climate science and math.

    At my alma mater Climate scientist Mike Schlesinger has challenged the Equilibrium Climate Response as well as the Transitional Climate Response of the IPCC. Mike is not alone and several other climates scientists are weighing in with lower calculations. Unfortunately Mike's study and other studies were too new and did not make the IPCC submission deadline. These new calculations lower climate sensitivity to a doubling of CO2, which GCMs are based on, by 50%. That would significantly alter multi-decadal projections. Still newer is the study by Judith Curry on the "stadium wave effect" which finds that natural/cyclical climate system signals can be stronger than climate signals from CO2 forcing and that a warming hiatus or possible cooling may continue into the 2030s. This would also have serious repercussions on GCMs as they do not now account for this. It sets up a measurable test of GCM accuracy as they project continuous warming into the 2030s.

    I have done my own investigating including data discussion with the MET Office in the UK who had published IPCC model testing in the "2008, State of the Climate" report put out by the AMS. At issue is that if models are biased to warming on decadal scales, it is doubtful that their 50 year projections going forward are accurate. We will not have to wait very long to know for sure if the models are accurate but I am of the belief we need to confirm accuracy.

    lastly you should take your own advice to anonymous12 and either cite IPCC AR5 WG1 by chapter/section, blogs written by climate scientists/climatologists or published science studies (the "stadium wave" paper I metioned is already here at Science 2.0) rather than linking to Think Progress.