A Free-Market Energy Blog

Unloading Hansen's 'Climate Dice'

By Chip Knappenberger -- September 24, 2012
“Today’s temperature ‘extremes’ are simply yesterday’s extremes warmed up a bit, partly from the heat-island effect. But they are not new events…. Hansen’s push on weather extremes is another case where the level of alarm is disproportionate to the level of impact.” 

Today’s temperature “extremes” are simply yesterday’s extremes warmed up a bit, partly from the heat-island effect. But they are not new events where none existed prior.

This distinction is neither subtle nor unimportant. When it comes to temperatures, yesterday’s extremes warmed up offer less of a surprise (and hence a greater ease of adaptability) than if a new crop of extreme events suddenly sprung up out of nowhere to catch us unprepared.

But such a distinction is not made prominently evident in the latest work by NASA’s James Hansen—and even less so in the accompanying media coverage (including that instigated by Hansen himself). Instead, the general audience is left with the distinct impression that anthropogenic global warming (as a result of greenhouse gas emissions from fossil fuel-based energy production) is leading to the occurrence of new extreme weather events when and where such weather events would not otherwise have occurred. For instance, in a Washington Post op-ed written by Hansen to accompany the release of his paper recently published in the Proceedings of the National Academy of Sciences, Hansen writes:

Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.

The deadly European heat wave of 2003, the fiery Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year can each be attributed to climate change. And once the data are gathered in a few weeks’ time, it’s likely that the same will be true for the extremely hot summer the United States is suffering through right now.

But this impression is untrue. These events and others like them, almost certainly would have occurred on their own (i.e., naturally). Climate change may have added a pinch of additional heat, but it almost certainly did not create these events out of thin air (see here for example).

But Hansen pushes this impression with his analogy of “Climate Dice.” The idea is that anthropogenic greenhouse gas emissions have “loaded” the dice towards extreme warmth, so now when Mother Nature rolls the dice for summer weather, there is better chance of rolling a heat wave, or an overall hot summer—events discreet from events that were contained on the unloaded dice.

But Hansen’s hot summers are not new discreet events at all. Instead, they are the naturally occurring hot summers with a few extra degrees added to them. The extra couple of degrees push some summers over an arbitrarily defined threshold temperature above which Hansen classifies them as being “extreme.”

Hansen’s threshold between a “normal” summer and an “extreme” summer has no physical meaning—instead it is rooted in statistics. While certainly some temperature thresholds exist that have physical meaning—like the 32°F, the freezing/melting point of water/ice—none exist in the range of temperatures which characterize summer across much of the globe. Whether or not the average summertime temperature is greater or less than some arbitrary value is of little practical significance.

Washington, D.C. Example

Let’s take the nation’s capital as an example. The mean summer (June through August) temperature in DC during the 30 year “base” period used by Hansen (1951-1980) was 77.0°F. The standard deviation—a statistical measure of the amount of year-to-year variability that exists about the average—was 1.2°F. Statistically, 67% of all values lie within one standard deviation of the mean.

For Washington DC, it means that 2/3rds of summers between 1951 and 1980 should have had an average temperature between 75.8°F and 78.2°F. Again, statistically speaking, 95% of all average summer temperatures should lie within two standard deviations, or between 74.6°F and 79.4°F. And less than one-half of 1% of all summer average temperatures should lie outside three standard deviations from the mean.

Hansen defines an “extreme” summer as one that is hotter than 3 standard deviations above the mean. So, for Washington DC that would mean a summer with an average temperature greater than 80.6°F—a situation that would almost never occur in the climate of 1951-1980 in DC.

Now let’s fast forward to the climate of the most recent 30 years. During the period from 1983-2012, the average summer temperature was 78.0°F—a full degree higher than it was during the base period. And, two summers (2009 and 2010) exceeded 80.6°F (that is, were more than 3 standard deviations above the 1951-1980 average). By Hansen’s reckoning, these were global warming induced climate “extremes.”

But are these hot summers entirely caused by global warming (or rather, climate change)?

If we went back and added 1°F to each summer from 1951 to 1980, one of them would have exceeded three standard deviations, and several others would have been close. In other words, the current climate of DC is pretty similar to the past climate of DC, just warmed up a bit. It is not a completely new climate replete with a different array of extreme events conjured up by human greenhouse gas emissions.

So yes, it is true that summers in DC are hotter than they once were. But local land-use changes (the increased heat-island effect) largely to blame.

Compared to past climates, more summers now meet Hansen’s arbitrary definition of being “extremely” hot. But climate warming is not responsible for all the heat, instead it just adds some warmth to what would have been a hot summer anyway.

Certainly, the hotter it is in DC, the more air conditioners run and other costs incur as well. And quite possibly, the costs increase in some non-linear fashion (see here for a discussion). But, it is almost certain as well that the costs do not rise anywhere near as swiftly as the tally of events crossing some arbitrary threshold by which to define and “extreme” event.

Hansen’s push on weather extremes is another case where the level of alarm is disproportionate to the level of impact.


  1. cknappenberger  

    John Christy took a further look at the occurences of weather extremes, as well as how Hansen’s recent analysis does not fairly represent them, in testimony last week before the House Energy and Power Subcommittee. It is worth checking out (see here).



  2. Eddie Devere  

    Hansen’s discussion of extreme climate is definitely alarmist and disingenuous. Some of the best analyzed data I’ve seen appears in a paper by Donat and Alexander. (See links here)
    http://www.skepticalscience.com/pics/DonatFig1.jpg (Main figure)
    http://www.leif.org/EOS/2012GL052459.pdf (Paper)

    The conclusions I reach from this paper is that (1) average day and night temperatures have increased globally between 1951 and 2010, (2) the average night temperature has increased more than the average day temperature, (3) the standard deviation of night temperature has decreased in the US, has increased in Canada, remained nearly the same in Europe, and has both increased and decreased in different locations in Asia, (4) the standard deviation of the day temperature has increased in some locations and decreased in other locations, and (5) the skewness is becoming closer to zero (it’s becoming less skew….see Figure 2 of the paper.)
    So, these are the conclusions to draw from the data in the Donat&Alexander paper, and now I’ll add in some conclusions I’ve drawn from similar data. There is now pretty solid evidence that increasing the amount of GHG’s in the atmosphere will increase the mean winter temperatures more than than summer temperatures. All data I’ve seen also suggests that the Arctic, Canada, and Siberia are warming much faster than locations closer to the equator.
    Since the temperature difference between the Arctic and the equator is one of the main driving forces for weather (i.e. moving temperature and pressure gradients), this may explain why in many locations there was a decrease in the standard deviation of the temperature. It would make sense that as the temperature in the Arctic increases faster than the temperature at the equator, then the fluctuations in temperature should decrease. In other words, global warming does not appear to be driving the climate to have greater standard deviation in the temperature.
    Therefore, it is disingenuous of Hansen to focus on the ‘hot extremes’ while ignoring the fact that there will be a decrease in ‘cold extremes.’ Climate changing is having it’s largest effect on increasing the average night temperature in the Arctic winters. The lesser increase is the average day temperature near the equator in the summer.
    So, we have all this data of past temperature change, but the question is: how should we respond to such data? Data by themselves can not tell us how to act. To know how to respond, you have to have an underlying ethical foundation. The problem of course is that we all have a different understanding of ethics. Some people think that ethics means saving people’s souls; some people think that ethics is growing life; some people think that ethics is doing whatever makes you happy; and some people like Hansen think that ethics is returning the biosphere to its state in ~1800.

    I believe that the goal of life is to grow life. So, I try to keep up with what’s going on around me so that I can best make decisions on how to invest my time&money to help grow life. It appears to me that, in the short term, there will be more people and other life forms that will be benefit from the increase in night/winter/Arctic temperatures than will be damaged by the increase in day/summer/equator temperatures. Though, I recognize that this may change in the future (there is very likely a point in the future at which the net benefits of increased temperature turn into net harm. As suggested in the meta-study by Tol in 2009 on the economic impact of global warming.)
    I also recognize that it makes sense to me that those people impacted negatively by average global warming should be compensated by all of us who use emit GHG’s. Since global warming should help the economic development of Canada and Siberia, which should trickle down across the globe as they spend their new wealth, we should on average be rich enough to pay taxes on GHGs to compensate those people and environments that are negatively impacted. (i.e. a Pigovian tax on GHG emissions.)
    In other words, when I study the data and apply an ethics of growing life, I see that the correct action should be one of cautious optimism (start growing life in the places that will warm and have emitters pay a tax on GHG emissions that compensates those who are negatively effected.) In the long run, we will probably need to significantly cut back on GHG emissions, but the question is always: what should we do right now? (Not what should we do 100 years from now.) Right now, we need to make investments that help life grow as fast as possible. Based off of the data I’ve seen, I’m cautiously optimistic that global warming is good in the near term. It is likely harmful in the long-term, but once again, I’m cautiously optimistic about our long-term ability to implement a range of different technologies with decreased emissions of CO2: such as rooftop solar PV, hybrid fuel cell vehicles that power your car and your home using natural gas, and CO2 capture from large scale power plants.
    In other words, I’m optimistic about our ability to grow life both now and in the future.


  3. Jon Boone  

    “I also recognize that it makes sense to me that those people impacted negatively by average global warming should be compensated by all of us who use emit GHG’s.”

    OMG! Well, there it is: The certainty that problematic “global” warming is caused by greenhouse gasses, which by the moral imperative of fairness mandates that those who burn more greenhouse gasses should somehow compensate those who burn less for any damages that this precipitous warming may incur. Summary judgment for the redistributionists.

    Let those regressive carbon taxes roll. And watch greenhouse gas emissions continue to increase, as those now emitting less will want to emit more in order to achieve modernity parity.

    Ain’t we got fun….


  4. Eddie Devere  

    What point are you trying to make? It’s unclear from your statements what you are trying to convey. It would help if you could explain (a) what type of ethics you believe in, (b) are you suggesting that the climate will not get warmer with increased GHGs?, (c) if not, what does your ethics suggest that you should do given the evidence so far that increased levels of CO2 will on average increase global temperatures? (though, of course, it appears to increase winter, Arctic night temperatures the most)


  5. Jon Boone  

    You and others could not make a preponderance of evidence case, let alone one judged by reasonable doubt, that humans are “causing” the bulk of any precipitous warming of the earth. There are many other possible causes, individually and in tandem, as you surely know. It’s not clear to me that whatever the present (last 100 hundreds) blip has been in the earth’s climate situation isn’t the result of cycles we poorly understand at present. As I’ve said repeatedly on this forum, I think, with the best evidence, that climate is so complex that we have only begun to understand some of the factors involved. Consequently, our measurements and our models are insufficiently informed, allowing us to draw incomplete conclusions, at best. I do work to understand the weather, however, a science that we know a lot more about. And need to learn a lot more. Earth is not a greenhouse. And it is not at all clear that increased CO2 is the proximate cause of those increased temperatures, if they are indeed part of a long term trend (100 years should represent any trend in the context of climate analysis).

    As for my ethics, I’ve never liked robbing Peter to pay Paul, particularly when Peter has done nothing to Paul but improve his style of living. Fossil fuels have been so incredibly beneficial to virtually everyone, including much of the environment, that taxing their use to compensate for a largely imaginary victimhood seems starkers, something out of dystopia. Those who would tax me for this purpose–while screwing the poor and middle class of this culture–share an ethics I want no part of.


  6. Andrew  

    Eddie- I think on scientific matters you make largely good points, but I find that your discussion gets a little off the rails from there:

    “Some people think that ethics means saving people’s souls; some people think that ethics is growing life; some people think that ethics is doing whatever makes you happy; and some people like Hansen think that ethics is returning the biosphere to its state in ~1800.”

    These are strange caricature philosophies. I guess that the first is a caricature of Christian philosophy, the second is, utilitarianism of some sort? I don’t know, it’s all meaningless gibberish poetry, fitting since this is your own philosophy. The next is a caricature of Objectivism, and finally a caricature, albeit perhaps the most accurate one, of environmentalist philosophy. For my part I feel as if my own philosophy is not presented at all. But as for your own philosophy, it leads you most astray when you recommend a “pigovian tax” in an attempt to correct an aggregate harm done to some segment of society and discourage aggregate behavior of people. We are not dealing with abstract collectives or poetic things like the “whole of life” and “growing it”- individuals may allege a particular grievance against their rights-harm as damage to their property. This is normally settled in the court system, not with society wide redistribution through the tax code.


  7. Eddie Devere  

    I asked about ethics because I wanted to know what you think the goal of life is, so that I could understand what your comment meant.
    There are and will be more victims as the climate increases in temperature (and there will be people who benefit.) One thing I’m saying is that we shouldn’t be alarmists like Hansen (i.e. suggest that we shut down the entire fossil fuel economy because some people will die during a heat wave or are forced to move off their island homes.) Since in the short term the benefits of a warmer climate outweigh the costs of warmer climate, all I’m saying is that anybody that emits GHGs should be taxed, regardless of location on the globe…and the taxes should go directly to some int’l agency that can provide water/food to people during heat waves and that can help relocate people from locations like low-lying islands.
    My discussion of a Pigovian tax has nothing to do with redistribution. I don’t want my income going to bureaucrats or to people who didn’t earn it. Figuring out who deserves compensating from this global warming agency will be very complicated (just like in the case of businesses harmed by the decrease in tourism from the oil spill in the Gulf of Mexico.) But I think that it’s better than the two extreme alternatives, which are: (a) do nothing and hope that heat wave / sea level victims don’t take their anger out at us, or (b) shut down the fossil fuel economy.
    Also, I didn’t say anything about taxing fossil fuels…I said taxing greenhouse gas emissions. There are plenty of ways of using fossil fuels while sequestering the greenhouse gases underground. Fossil fuels are a cheap and abundant energy supply, and should be used in the future. It’s not the fossil fuels themselves that are the problems. The problem is that if we continue to combust fossil fuels at the rate we going (and if plants don’t quickly step up their rate of photosynthesis), then we are likely to reach a concentration of CO2 in the atmosphere of >600 ppm, which will likely lead to average temperatures higher than we have seen in the last 10,000 years.
    So, I would also argue that any landowner is entitled to some average temperature over that land that falls within the average for the last 10,000 years (or average sea level.) If the CO2 levels were to increase to 600 ppm or 1000 ppm, we will likely push the temperature way past where it’s been since the last ice age and push sea levels way above where they have been during that time period. Therefore, I see the problem of global warming as a property rights issues.
    That’s why your discussion of stealing from Peter to pay Paul breaks down. What I’m saying is that we need to respect property rights. We don’t have the right to emit greenhouse gases into the environment and destroy somebody’s property without having to pay a tax to compensate the landowner.
    The reason why I’m optimistic about the future is that (a) we will be able to compensate those negatively impacted without destroying our economy (since the benefits outweigh the negatives in the short term) and (b) in the long term, we will have plenty of low-GHG emitting technologies that will be quite affordable, many of which (like solar PV and NG-derived fuel cells in our vehicles that could also power our homes) don’t require us to buy electricity from the grid and which will force regulated utilities to compete by lower prices. The price of solar PV has been dropping to less than $1/W for the panels, and when it reaches $1/W for the panel+installation (which is likely now that companies are starting to eliminate useless steps from the silica-to-doped-silicon process…just as Andrew Carnegie did over time as he eliminated some of the useless steps in making steel.) By the time that CO2 levels are a real problem, solar will likely be able to compete in most locations regardless of whether we tax GHG emissions.
    The future will be better than the present for most people. To make it better for even more people, I think that we need to compensate those people who are negatively effected by climate change. Anybody who emits greenhouse gases should have to pay into this fund because it’s a global issue.


  8. Michael Moon  

    “Much Ado About Nothing.” Data does not show that we have altered the climate at all. We don’t have good records going back much over 100 years, and those that we do have are subject to tampering by activists. Just exactly how hot, cold, wet, and/or dry was it before 1850? Nobody knows, certainly not tree rings….


  9. Jon Boone  

    You may have the last word on this, since I’m not going to respond further, except to say:

    1. The 35 billion metric tons of CO2 humanity emits into the air and water is nontrivial. I don’t know what the long term consequences of this are, and I don’t think anyone else does either. There are a number of scenarios, including yours. Nonetheless, it seems reasonable to begin reducing our emissions–but in scalable, realistic, functional ways. (Solar has local, distributed potential but is not grid worthy or scalable.)

    2. The United States may be showing one way to do this already, without taxation of the kind you suggest. Using carbon taxes to reduce fossil fuel use is problematic at a number of levels, ethically and practically. Such a tax would be unfair to the poorest among us, make life more difficult for much of the middle class and particularly its rural component, and put brakes on much of the world’s most productive economies. Moreover, how ethical is it to tax the public for calamity that may neither be calamitous nor the fault of humanity?

    3. I’ve lived through too many trumped up “scientific” rationales for environmental apocalypse to buy into your narrative. I didn’t think it was “right” for me to contribute to a reclamation fund for the victims of the Mayan Calendar apocalypse. Similarly, I sequestered nothing for those harmed by acid rain and the ozone hole depletion supposedly caused by CFCs. I don’t even feel sorry for those of us who will be left behind after the coming Rapture.

    4. The United States already conducts a Baptists and Bootleggers routine similar to that which you recommend. It’s essentially represented by FEMA to reparate victims of mainly weather related events. You and I already are being dunned for taxes to reward some of the stupidest land use practices imaginable. Why are government or insurance companies continually bailing out cities built below sea level that cannot afford the proper levees needed to protect them adequately from 10, 20, 50, 100 year storms that cause damage in the billions of dollars at each iteration? Ditto for those who build in areas well known for flooding and fires (particularly in ecosystems where fire has been a necessary part of the action for millions of years). We’re already spending billions in “socialized dollars,” taxes, on cleaning up the aftermath of predictable environmental events that don’t require “climate change” to explain. It’s not a success story.

    5. Carbon taxes are also impractical because any reductions in fossil fuel use in the USA due to such taxation would be a drop in the bucket world-wide, since countries like India and China are committed to achieve modernity via the fossil fuel route. And I daresay that over the next quarter century, they’ll be joined by much of Africa and Indonesia.

    I hope we would not reduce emissions because of (very misguided) policy dedicated to saving the planet from precipitous warming mostly due to burning fossil fuels. Rather, we should be doing it because of its yet unknown consequences and because it’s more efficient, more affordable, and more amenable to getting more productivity in less space, in the process conserving our most sensitive ecosystems and supporting biodiversity.

    Besides, in my ethical world and, evidently, in yours as well, fossil fuel consumption is not a sin. It cannot be fairly compared to tobacco or alcohol, those traditional sin-taxed icons of the save-humanity-from-itself crowd. Fossil fuels are a good thing by almost every measure. They should be encouraged to help bring the rest of the world greater comfort, more productive health, and more expansive leisure. Sure, if we can afford to back down on their emissions locally, let’s do it–affordably and with the least disruption possible.

    Meanwhile, because we seek an even more productive future, let’s continue to explore ways of bringing the nuclear option up to speed– bootstrapping us toward yet undreamed wealth and power that should characterize much of the 21st century, particularly since nuclear fuel is so dense (millions of times more so than fossil fuels), allowing us to fashion extraordinary tools, ones that can enhance a sense of personal freedom and give billions of people freedom from want. And, as a bonus, we would be continuing down our thousand year path of decarbonizing culture.

    However, I can only imagine the eschatologies that will emerge by 2050 to warn of the next apocalypse. That marvelous self-reinforcing Baptist and Bootlegger feedback loop will continue to cast a pall over even pedestrian progress, as it has for much of human history.


  10. Ed Reid  

    Michael Moon @ 8

    Data shows that the global climate has warmed. However, that data is unusable without “adjustment”, meaning that it is of questionable quality. The US arguably only has “good data” from surface stations beginning about 10 years ago, with the implementation of the US CRN. We have global satellite measurements with far more comprehensive coverage than the surface stations, but only over the past ~30 years.

    We certainly do not know enough to justify investing ~$30 trillion to move to a zero carbon emissions society in the US, no less ~$150 trillion globally.


  11. rbradley  


    One can be for a carbon tax outlined by you above in theory but not in practice because government failure trumps market failure. Some things we live with, and the human influence on climate is surely one of those things given the uncertainty of magnitude and effect.


  12. KevinM  

    Who is that lead quaote attributable to?

    [The lead pull quote is just taken from my article. It is my writing. -Chip]


  13. KevinM  

    Thanks. WUWT posted it as a Hansen quote.


  14. _Jim  

    KevinM, Chip; the pull-quote attribution has been corrected on WUWT “Chip K”.



  15. Kurt in Switzerland  

    Chip –

    (I’m a visitor from WUWT)

    I agree that incidences of temperature extremes > 2 or 3 sigma above mean values from 1951-1980 may be a direct result of the “warm” multi-decadal phase (and thus not an indicator of permanent warming at all); given the observed approx. multi-decadal cycle of 60 y, it would make far more sense to calculate and compare “temperature anomalies” from a baseline of 60 y, e.g., 1920-1980, 1930-1990, 1940-2000, etc. This point needs to be repeated loudly and clearly.

    I am taken back by the extreme politicization of this subject. The assumed (but scientifically unproven) effects of the well-documented rising atmospheric CO2 concentration have created an industry with a vested interest in fear-mongering. Furthermore, there is an unwritten belief in the power of “climate mitigation policies” which have zero effectivity in controlling overall CO2 emissions, let alone stabilizing atmospheric CO2 or having a measurable effect on climate itself. In addition, the love affair with anything tagged “sustainable”, “green” or “renewable” is causing several governments to make extremely poor energy security decisions which in many cases are also sheer financial folly.

    It is high time that scientists from fields outside of climate investigate closer, inform themselves and challenge the “orthodox view” in public. There is too much at stake.

    Aside: you might want to change the spelling of discreet to discrete (word used twice in your article).

    Kurt in Switzerland


  16. Mya  

    David: Because that is what this all boils down to. FYI, The GAO has determined NOAA’s GHCN is FUBAR and needs aettntion to meet it’s own requirements for siting going forward. The results are so bad historical records should be discarded, but that it what I have been saying for years. As was just pointed out Mann’s paper was actually a regional reconstruction of a single site in the Sierra Mountains using trees that are now known to be useless for climate reconstruction because of their growth characteristics. It seem that if you take four cores from one tree you get four separate growth patterns and neighboring trees also have separate characteristics for the same years. It was just a matter of picking the trees that displayed the results you want. That is just one set of trees and it destroys the entire paper’s results and Mann’s reputation because he continues to claim he was right. Because of the actions of the Climate establishment they have destroyed their own reputation and pulled the IPCC down with them. Recently the scientific societies were damaged by not understanding the problem and you are guilty by your own words of encouraging illegal activity and aiding and abetting people that are using fraudulent means of obtaining money from the government. There is no viable paleo record to compare today’s climate conditions with. There is no viable historic surface temperature record to compare today’s climate with. NOAA is a point where they have been told to start over and do it right next time because they failed to maintain their own standards. That just discredits all the work product of the NOAA. But of course they are the agency that provided the other groups around the world with the GHCN data. Two legs of the IPCC tripod are broken. Should I discuss the third? Sure why not! Models! Basics: The models can not replicate clouds which are an important part of global weather. Seeing how climate is weather over a long period of time. The model input as failed because it can not properly characterize clouds. But it gets better. With 22 model outputs, of which none can replicate past climate to any degree of usable accuracy, They each failed the test, they want to the the average of 22 bad model runs to show the most likely future scenario thinking that 22 failures will give a better projection than one good one. Remember the models were tested against historic temperature records provided by NOAA, who has been found to have bad historic records. The models were tested against paleo proxies that have been shown to be worthless. I wonder what the modelers were doing other than playing what if games on their expensive toys because they did not attempt to verify the value of the weather information that they were trying to replicate. GIGO big time! Now stop and think about all the money that has been wasted chasing a fairy tale and out visitor Dave wants us to waste even more by throwing it down the hole that is the climatology and IPCC fiasco. Dave: Why do you insist on defending these frauds and promoting this Chicken Little Fairy Tale?


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