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Betting on climate change

Filed under: — group @ 14 June 2005 - (Romanian) (Ukranian)

Guest contribution by James Annan of FRCGC/JAMSTEC.

“The more unpredictable the world, the more we rely on predictions” (Steve Rivkin). The uncertainty of an unknown future imposes costs and risks on us in many areas of life. A cereal-growing farmer risks a big financial loss if the price of grain is low at harvest time, and a livestock farmer may not be able to afford to feed his herd if the price of grain goes up. One way to reduce the risk is to hedge against it in a futures market. The two farmers can enter a forward contract, for one to deliver a set quantity of grain to the other for a fixed price at a future date. And indeed farmers do routinely use futures contracts to reduce their risks.

Weather is a major uncertainty affecting our futures (it is one of the main sources of risk for those farmers), and weather futures markets can be used to hedge on the monthly/seasonal time scale. In the longer term, changes in climate will also bring a range of costs and benefits, and a market in climate futures would allow anyone who is vulnerable to hedge against these risks too. But how can we assign fair prices to the contracts? One obvious starting point would be to look at model predictions and historical data. This is essentially what the IPCC does, eg with its estimate of 0.3+-0.1C /decade for anthropogenically-forced warming over the next 20 years in the absence of substantial mitigation of emissions (at the “likely” level, ie 66%-90% probability). If we want to work out the probability of global mean temperature being warmer 20 years from now, we could take this 0.1C in uncertainty of anthropogenic forcing (which I will assume to be 1 standard deviation of a Gaussian deviate), and add another 0.15C of independent natural internal variability, which gives a combined estimate of 0.3+-0.18C warmer overall or about a 5% chance of cooling. To this, we can add perhaps another 5% due to the possibility of a large volcanic eruption at the right time, making 10% in total. Now before you all write in telling me my assumptions are wrong, the real answer should be 20%, or 4%…that’s precisely my point. Of course my simplistic assumptions can be questioned, and I could have performed a more accurate calculation, but however carefully it is approached, this sort of forecasting inevitably involves subjective judgement and assumptions. The IPCC estimate depended on expert judgement, so someone who believed that they markedly overstated the anthropogenic influence might deduce that the chances of cooling were closer to 50%, and an advocate of the more extreme solar forcing theories might even confidently predict significant global cooling. So ultimately it seems like we have no really firm, provably correct and objective basis for setting a market price.

Fortunately, there is a solution to this problem. Efficient market theory states that the price in a free market should accurately reflect the aggregated information that is available, and so in 1990 economist Robin Hanson noted that we can turn the problem around: use the market as an aggregation mechanism to tell us what the odds are on any particular event. This, he claims, could be much more effective than relying on panels of government- (or self-)appointed experts and media pundits to predict the future, since the financial penalty would keep the incompetent away from the marketplace, and the real experts would be automatically rewarded for correcting any errors in the market prices. There is now a growing body of evidence in support of these theories, including for example the analysis of existing markets and results from a market which was set up specifically to investigate the idea further. Of course the market price does not exist in a vacuum: in practice, traders would perform calculations as I did above (but rather more carefully), and the market price would reflect their consensus. The market is a highly inclusive mechanism: rather than having to debate to the death, anyone who has an opinion can invest as much as they want (which will relate to their confidence), and in the long run the winners will drive out the losers. If I offer (and accept) bets on global cooling at 10:1 based on my rough calculation, someone who does a better job of estimation will probably be able to take money off me, earning a reward for their skill and effort.

The Foresight Exchange market is an internet-based game which runs an ideas futures market, covering a wide range of claims including a number of environmental issues. The basic betting mechanism is based on the concept of a pair of coupons labelled “Yes, claim X is true” and “No, claim X is false” (where X is a proposition whose truth is not yet known). These coupons can be bought and sold individually on the open market, and a pair of them can always be bought or redeemed for $1 from the bank. When the claim’s truth is determined, the correct coupon is redeemed for $1 and the false coupon becomes worthless. The market price of the Y coupon is the market’s estimate of the probability of the claim being ultimately proved true. Here are a couple of examples – indicating how confidently (or otherwise) the market predicted the re-elections of Clinton and Bush in 1996 and 2004 respectively.

The Foresight Exchange is a small market with a limited number of players, and is certainly not perfect – I presented a simple analysis in a poster at the EGU in April, and I have also discussed a couple of claims in more detail here and here. (These are a slightly different type of claim, where the payout of the Y coupon depends continuously on the value of a variable at a specified future time – such as the global mean temperature in 2030. The N coupon pays $1-Y as before.) As Hanson’s theory predicts, by participating in the game, I have both improved the price on these claims (increasing market skill) and simultaneously increased my wealth (received a reward for my contribution). Although this small and non-serious market has noticeable inefficiency, a real money market could certainly hope to do better. So what are the drawbacks? It seems that there are are surprisingly few. Fears that rich vested interests could rig the market are generally misplaced: it would cost them a lot of money to do so, potentially much more than the price of influencing a few high-ranking experts. Robin Hanson’s pages have a great deal of discussion about the various criticisms of the idea that have been offered, and also how the basic idea could be extended to cover a wide range of applications.

I’ve recently been trying to establish consensus on the subject of global temperature rise, by arranging bets with sceptics who claim that the IPCC TAR is overly alarmist. Richard Lindzen was the first I noted who forecast here that over the next 20 years, the climate is as likely to cool as warm, and said he would be prepared to bet on it. However, when challenged to a bet, it turns out that he expects odds of 50:1 in his favour, ie he will only bet on the chances of cooling being at the 2% level or higher, far short of his 50% claim. My quick and dirty estimate above based on the IPCC TAR suggests that they would put the probability at more like 10%, so his offer actually appears to affirm the IPCC position. He also suggested an alternative bet (see here for my comments on this article) based on the amount of warming: >0.4C warmer and I win $5,000, <0.2c and he wins $10,000. Again, no-one who believes the IPCC summary would find his offer attractive, since it has negative expected value. The chances of winning and losing are roughly equal, so there does not appear to be any possible justification for his expectation of a 2:1 ratio (in his favour) in the stakes. In both cases, in contrast to his words, his position seems to be more alarmist than the IPCC!

The list of sceptics who have refused to bet against the IPCC position has grown steadily since then, and now also includes Michaels, Jaworowski, Corbyn, Ebell, Kininmonth, Mashnich and Idso (all my blog posts and related comments are linked from here). While I would be happy to take money off any or all of them, there is more to this than sceptic-bashing and a few high-profile bets – it could also perhaps result in a working market that would generate a true consensus and, furthermore, provide the socially and economically valuable function of allowing the vulnerable to hedge against risks.

[2005/06/24: comments on this post are now closed. This post generated a record number of comments: thanks to all those who commented. For any further follow up, you are recommended to the discussion on the newsgroup sci.environment – William]

125 Responses to “Betting on climate change”

  1. 51
    John Finn says:

    Regarding the original article, Richard Lindzen is quite right to expect favourable odds. Betting odds are not just based on the likelihood of a particular result happening; they also reflect the popular appeal, i.e. the number of people who actually take (or are likely to take) the bet. These are not necessarily the same thing (e.g. England in the World Cup)

    As there is such a strong consensus for AGW (reportedly 98% at least), Lindzen’s 50 to 1 – although a bit high perhaps – is in the right area.

    On later comments

    I’m not sure why there is so much caution among the global warming advocates. James Hansen (along with Gavin) and others have recently reported that there is 0.6 deg C warming in the pipeline. The majority of this must become evident in the next decade or so. Atmospheric CO2 levels will continue to increase anyway. Barring an unprecedented run of volcanic eruptions the pro-warmers would appear to be the red-hot favourites. The odds need to reflect this

  2. 52
    Terry says:


    Why no mention of the bet that Junkscience is proposing?

  3. 53
    Michael Jankowski says:

    RE#11 response,

    We’re talking about skeptics making bets. A skeptic is going to wager based on what he/she believes, not what you believe. If someone believes we’re naturally coming out of a cool period (which Lindzen, etc, may believe), they’re much less likely to take a wager that we’ll be cooler 20 yrs from now or will want better odds than a flat wager. You may think you have supporting information that the LIA didn’t exist or wasn’t abnormally cool, that 20th century temps were abnormally high, etc. But if a skeptic disagrees with you on some of those points (and many/most would), then they very well could be expecting global average temps to warm naturally over the next 20 yrs.

  4. 54
    Joel Shore says:

    Re #47 and 48:

    (1) You have given an example of a sudden warming from a glacial state to interglacial or near-interglacial conditions. However, what we are talking about is a sudden warming from what are already “balmy” interglacial conditions…a warming that, if it continues, will likely surpass the temperatures in previous somewhat warmer interglacials (like the one immediately previous to the current one ~100,000 years ago…when the sea level is believed to have been several meters higher than it is today).

    (2) Your example of a heat wave in New Dehli being 0.37 degrees warmer is a red herring. What we are talking about is not a warming that is completely uniform in space and time but one that makes extreme weather events such as strong heat waves considerably more likely. I.e., I do not think it is correct to simply conclude that you add 0.37 degrees, or whatever amount, to each daily temperature.

    (3) While your concern for the Inuit is touching, those folks are well-adapted for the cold climate that they live in and, in fact, they are one of the groups that is most concerned about severe negative consequences to their way of life due to global climate change.

  5. 55
    Dano says:

    So, amidst all the hand-waving, has anyone determined whether Bahner indicated that he’ll take the bet? Has anyone actually nailed him down?

    I must admit I enjoy his spectacle and will miss the show when he disappears.

    So, anyway. Has he taken a bet?


  6. 56
    Christopher M. Nicol says:

    I am a simple working class individual living in the suburbs. My question pertaining to global warming is common. I wonder how long it may be before the worlds societies are forced to drastic “near overnight” change? I am especially curious about the United States, as this is where I reside. How will this affect our lives, and more importantly at about which point should we expect catastrophic societal events. I ask this answer not in terms of years, but rather in generations.

  7. 57
    Brian S. says:

    I can’t find the bet offer that’s supposed to be on Can anyone give an exact URL and/or reproduce it in the comments here?

  8. 58
    Michael Jankowski says:


    I assume you’re trying to link GW to the droughts in Australia. I, too, read about the farmer suicide rates there. The only information I can find is a copy the same article at a variety of sites (such as this one, and it isn’t specific about the regions sufferent from droughts. It does, however, mention the New South Wales Famers’ Association and someone in Barellan (also in NSW). I also verfied here that NSW is under severe drought conditions thanks to low autumn rainfall .

    If this drought is due to GW, we should be able to see similar events due to warm global temps in the past, correct? Well, the best Aussie rainfall data I could find was here , and it’s limited to the period of 1910 through 1995. But I think in general that when you use the interactive site and look at rainfall for NSW and Australia as a whole both over autumn and the entire year, you don’t find a very good correlation between warmer global temps and droughts. You will also see that there is a tremendous amount of variability from year-to-year. The Aussie Bureau of Meteorology states: “Drought is also part and parcel of life in Australia, particularly in the marginal areas away from the better-watered coasts and ranges” and that “Many, but by no means all, droughts over eastern and northern Australia accompany the El Niño-Southern Oscillation phenomenon.”

    Also, see this other Bureau of Meteorology link showing the annual rainfall over Australia from 1900-2002. It would be tough to blame GW for a widepread Aussie drought based on that chart, which suggests that the 1990s – the warmest decade of the century (or in history, according to some) shows some of the more consistent rainfall totals from year-to-year and which appear to be overall well above the 20th century average. Just to check, I downloaded the data, and it’s true. For 1900-1999, the avg was 453mm with a standard deviation of 80mm (for 1900-1989, those figures are 450 and 80). For 1990-1999, those figures are 485 and 72, respectively. So if anything, the warmest decade of the century/history brought more rain and less variability. As the website states, “The high year-to-year variability of Australian rainfall dominates any background trends. Some of this variability can be accounted for by the El- Niño Southern Oscillation.”

    Last-but-not-least, I came across this Aussie study of suicides which shows a link between suicides and sunlight in Aussies. So maybe the reduction of global dimming is to partly to blame!

  9. 59
    Jeffrey Davis says:

    I’ve followed this site for many months, and I have to say that this thread takes the cake for esoterica. I’ve no idea who is agreeing to what or what ideas are being advanced. Every phrase is hedged and qualified to the nth degree. All over imaginary money!

  10. 60
    Hans Erren says:

    There is of course also the Nenana Ice breakup bet, which is held every year in April (or May)

    [Response: This is about climate, not interannual variations, which are effectively weather – William]

  11. 61
    Glen Raphael says:

    The article has scrolled off the page, but you can still find it in the google cache. It didn’t specify a specific bet. It did point to a good recent Reason article.

    Bahner has officially posted a bet offer here. His prediction is that “the actual warming of the lower troposphere from 1990 to 2100, as measured by satellites, will be less than 1.94 degrees Celsius.” Splitting the difference between Michael Crichton’s prediction and one interpretation of the mean IPCC prediction.

    [Response:Bahner is weaselling, because his bet is only open “to members of IPCC” whatever that means. Insisting on going out to 2100 makes it less interesting/immeadiate than going to 2030. Giving any credibility to Crichton shows you where he is on the science. And putting in a value that is within the IPCC range is rather revealing – William]

  12. 62
    Steve Latham says:

    To Terry,

    I went to the junkscience website too and searched for Lindzen (as you instructed) and couldn’t find the bet either. Was that just a trick to get some hits at that website? For something that’s supposed to be debunking bad science, the discussion of the science is not very prominent.

  13. 63
    dave says:

    Re: Decadel Ranges and #49 James’ comment

    # 16,17,39 (dave): … you (and I) will have to wait for AR4, I’m afraid. I would be surprised if it was very different to the 2001 TAR version as far as the next few decades go, but I certainly have no priviledged information about that. [emphasis added]

    How can this be when each passing year (since the IPCC TAR) gets into the top 5 warmest years on record? Outside 1998, currently #1 because of the unusually strong El Nino, the next top 4 are 2002 (2nd), 2003 (third) and 2004 (fourth). And Hansen predicts 2005 will surpass 1998 even in the absence of a strong El Nino. Even if it doesn’t, it will probably displace some year in the top 5 (another wager!)

    We’re at 0.17C right now and I am assuming a 30 year moving average. 2 more years of this warming trend will surely move the decadel range higher than the TAR range of 0.1 to 0.2 for coming decades in the AR4. Assuming no really big volcanoes, of course! Given converging results from models for climate sensitivity (2.5 to 4.0C) and increasing GHG levels, decadel trends and predictions can only go up. Decreased albedo feedbacks and increased warming at high Northern latitudes alone guarantee your bet. I can only conclude that if you’re betting on climate futures, the time to buy is now. How about a AR4 oredicted decadel range of 0.14 to 0.24 C in 2007 for future decades? Any takers on that one?

  14. 64
    beth says:

    Sorry, this isn’t science but catching up: I remember Chip K. from…

    [Response:This comment was interesting but, regrettably, doesn’t come within the site policy so had to be removed – William]

  15. 65
    Dano says:

    Glen, that’s an old bet.

    We want Bahner’s answer to James. Will he do the standard Bahner hand-wave and eventually go away, or will he actually allow himself to get nailed down to a specific?

    What’s his answer to James? What’s the bet?


  16. 66
    Terry says:

    Here is the Junkscience discussion of the bet. I am sure James is deep in discussions with them as we speak. Keep us posted James. This has been the most interesting thread on this site yet.

    Hmm… how could such a wager be fairly structured? What positions could advocate and “contrarian” take? How would we determine the winner? What metrics could we use? Let’s see what we can come up with:

    Representing industrial-strength Anthropogenic Global-warming in the blue corner, let’s call them AG (please, no blind Patagonian Sheep jokes) and, in the red corner, we’ll have Usual Situation (US).

    So, we would have to assume AG would take the position of at least the median IPCC estimate of +1 °C over the 1990 figure by 2025 (our 20-year bet) and we’ve already hit a problem. The GISS Global Surface Air Temperature Anomaly (C) (Base: 1951-1980) suggests 1990 was a tad warm so we may be unfairly biasing against AG by using this figure. Let’s try the 5-year mean from that same record and make the bet on the 5-year mean for 2025 (not available until after 2027 because it averages 2 forward and 2 back from the target year). This looks a better proposition (ooh! sorry) since it will reduce El Nino and other transient effects.

    Now, we don’t have quite the number of records we’d like but -0.14 °C is the mean of the first 5 years of the record and is probably close enough for our requirements. US contends +0.5 °C over 11 decades is none too exciting and a continuation of that gentle recovery from the chill conditions of the Little Ice Age could lead to near enough +0.6 °C over 13.5 decades (to 2025, in other words) so 1990’s 5-year mean +0.11 °C.

    Defining our figures then we have AG punting for a target global mean temperature of 1951-1980 mean (14 °C*) + 1990 5-year mean of +0.36 + 1 °C for an aggregate of 15.36 °C and US tipping 1951-1980 mean (14 °C*) + 1990 5-year mean of +0.36 + 0.11 °C for an aggregate of 14.47 °C (rounded to 15.4 °C vs 14.5 °C here for convenience).

    Now we come to the problem of that darn “*” seen above. The estimated global mean absolute surface temperature 1951-1980 is 14 °C ± 0.7 °C. It’s like that because we’re really not that flash when it comes to determining the actual temperature of the planet yet and we could even be getting worse due to urban heat island effect (UHIE) corrupting the near-surface temperature amalgam (records such as GISTEMP are beginning to race ahead of atmospheric measures and the discrepancy appears to be worsening).

    Our situation then would appear to be AG punting a range of about 14.7 °C through 16.1 °C versus US with 13.8 °C through 15.2 °C and a mutually-claimed zone of 14.7 °C through 15.2 °C.

    What to do?

    We could declare the overlap a “no joy” zone, I suppose (should the house win or all bets off?). Then there’s unforeseen transients like explosive volcanic events in the preceding year or two – might need to declare such things as bet invalidators too…

    Climate’s not really a binary situation is it, rather more nuanced than usually presented and, given our precision difficulties, trying to work out just what is happening turns out to be looking through a glass darkly.

    What do you think? If you believe you can work out a fair wager for climate over 20 years, drop us a line. Workable entries may be published.

    [Response: I would just point out that the introduction of the mean global temperature and it’s uncertainty is simply a distraction to the principle point here which is related to temperature anomalies. As JS knows full well, the anomaly field in any of the data sets being discussed is much better characterised than the mean. To paraphrase the offer, they appear willing to bet on a continuation of the linear warming trend calculated from 1900 (around 0.06 C/decade) compared to James’s estimate of 0.1 – 0.2 C/decade. This may be doable…. -gavin]

  17. 67
    Eli Rabett says:

    Anyone who takes this bet is a fool,

    “Bahner has officially posted a bet offer here. His prediction is that “the actual warming of the lower troposphere from 1990 to 2100, as measured by satellites, will be less than 1.94 degrees Celsius.” Splitting the difference between Michael Crichton’s prediction and one interpretation of the mean IPCC prediction.”

    given that the method/algorithm for determining the lower tropospheric warming is not specified. There are about 5 of them, and they vary from 0.08 to 0.24 C/decade. Which is the best representation is a good start to what passes for a bar room brawl. Note that Anan is tying his proposition to the GISS surface record, which, whatever else you want to say about it, is well described and stable.

  18. 68
    Joel Kuni says:

    Most of the wagers proposed above seem to depend on future temperatures changes graphed as a function of time. As was noted by a couple of people, this implicitly assumes there won’t be any volcanic eruptions or any moderation of the increase of greenhouse gasses in the atmosphere. In my opinion, that puts too much uncontrollable risk into the wager.

    I propose that our wager should involve the behavior of temperatures as a function of the concentration of GHG in the atmosphere, rather than as a function of time, since that’s the foundation of anthropogenic global warming theories.

    I also propose we throw out any 12 month period following a volcanic eruption or the beginning of an El Nino event, neither of which are theorized to be caused by humans.

    Furthermore, since global warming models uniformly predict that the greatest anthropogenic warming will occur in the winter months in the driest, coldest climates, how about if we only look at average winter temperatures in the region of Anarctica, plotted as a function of mean GHG concentrations in the atmosphere of that continent?

    If global warming alarmists are correct, when we graph temperature as a function of GHG we should expect to see not only that a least-squares trend line fitted to multi-year data has a strong positive slope, but more importantly we should see a convincingly large value of R squared.

    I propose (tentatively) that I should lose the bet if the slope of the trend line is positive AND if the value of R squared is greater than 50%. (If it’s less than 50% it would imply that less than half the increase in temperature can be explained by the presence of greenhouse gasses, which implies to me that the earth has adequate defenses to counteract any warming forced by humans, in the long run.)

    If this wager seems fair to Those Who Know About Such Things, then I have a question. Don’t we have enough historical data to settle the bet right now, based on observations collected during the past 100 years or so? What do you suppose we will find if we look?

    Based on the skimpy data I’ve been able to locate (in a search lasting upwards of three minutes) I suspect I will win my bet handily. If I do, will that persuade those of you who tend to side with the alarmists?

    If I lose my bet, I will readily concede that Inuits should reduce their greenhouse gas emissions if they place less value on the human lives global warming will save from frostbite than they place on their “way of life” (which involves GHG-belching snowmobiles, according to ).

  19. 69
    Stephen Berg says:

    Re: #48,

    “Lynn, in #45 you refer to losses of human life that are supposedly already occurring due to global warming. Don’t forget to add back the lives that are being saved because there are fewer deaths due to hypothermia, frostbite, etc. Most of the warming occurs in the coldest parts of the earth and at night, not in the warm regions of the planet.”

    This statement is utterly ridiculous! Those who live in these colder climate regions have adapted and really have little chance of dying of hypothermia and frostbite. The Inuit of northern Canada and Alaska are completely adjusted to the cold climate, such that a warming of their climate would result in the destruction of their way of life (many animal species on which they rely for food and clothing will be drastically reduced), which may result in the reduction in numbers.

    “Also, the longer growing season and the increased concentrations of CO2 obviously improve crop yields, thus preventing deaths due to malnutrition and starvation.”

    Another ridiculous comment, since the “improved crop yields” in some fields would be offset, and then some, by desertification and the spread of disease and severe weather which will likely result (and is possibly resulting today).

    “The WHO apparently wants us to believe they know of people in New Delhi who died because, due to global warming that has already occured, the high temperature was 108.37 degrees rather than the pleasant 108 degrees it would have been otherwise. I guess they think we’re stupid.”

    Ummm. No. Look at the heat wave in Europe a summer or two again. That is what is happening and will likely get worse. Tens of thousands died there from the heat.

    Also the 108.37 degrees was the climatic AVERAGE, not the high temperature on a day-to-day basis. This means that there were likely extremes of daily temperature (perhaps 125 or so and then 85 or so), which would have resulted in the deaths of thousands.

    “I would like to know how the WHO justifies showing pity for overheated equator-dwellers while showing no pity at all for the Inuit victims of frostbite and malnutrition in northern Canada.”

    Again, the Inuit are not victims of frostbite! This comment shows extreme ignorance of any sort of reality.

    However, the Inuit are likely beginning to suffer from malnutrition due to the decreasing populations of healthy animals on which they rely for food as a result of the local climatic effects of global warming.

  20. 70
    Lynn Vincentnathan says:

    RE #58, I wasn’t necessarily attributing current Indian & Australian droughts to GW, only saying that farmers already in hock may not be able to hedge their future losses from GW. And I don’t think WHO is attributing GW-linked suicides & other deaths more indirectly linked to GW, so my guts tell me they may be underestimating the number of deaths. I have the feeling that as science improves & looks into all angles in the future WHO will look back on our era & say that deaths due to GW were much higher than they had estimated (even subtracting lives saved by GW).

    I do know that the warmth of the ocean does play a role in whether the monsoon drops rain over the ocean (when the ocean is a degree or so warmer) or drops rain over India, giving enough rain for its crops. I do know that GW is expected to have a tremendous impact in the future – also from melting Himalayan glaciers, which will increase flood damage in winter & leave them no water in summer for irrigation (maybe not even for drinking). Of course, there are many other environmental problems harming India & elsewhere, in addition to GW.

    I’m not sure if the ocean temps likewise affect Australian droughts. Does Austalia get monsoons???

    I guess I’d say that if the current droughts in Australia & India are not in any part due to GW (& I think they might be), then we can only expect much worse in the future. So why are we playing RUSSIAN ROULETTE re GW, when we could be saving mucho money from energy efficiency & conservation. Luckily I’m not a gambler, I’m a frugal person, so I’d rather save money AND reduce my GHGs. Win-win is much better than zero sum games.

  21. 71
    Joel Kuni says:

    Re #69:

    “Traditionally, Arctic hunters were at risk of hunting accidents (e.g. animal attacks, shooting and boating accidents) and death from exposure or hypothermia.”

    Please provide the source for this scientific statement: “Also the 108.37 degrees was the climatic AVERAGE, not the high temperature on a day-to-day basis.”

    I am astonished to learn that the average climactic temperature has been so high without my having noticed it!

  22. 72
    Stephen Berg says:

    Re: #71,

    “Traditionally, Arctic hunters were at risk of hunting accidents (e.g. animal attacks, shooting and boating accidents) and death from exposure or hypothermia.”

    Arctic hunters were, but those who stayed in the home were not, unless they ventured out while a winter storm was occurring. The Inuit were, and are, aware of what the harsh weather could do to themselves.

    They passed along knowledge and tales of those who survived and those who perished, which educated them at an early age of the dangers of their surroundings. This improved their odds of surviving.

    However, now, with the increases in temperature over the last 150 years or so, their environment is changing, which is increasing the risk of their culture being destroyed and will also likely render this past knowledge useless.

    Talk to Sheila Watt-Cloutier and ask her whether global warming is likely to be positive or negative. (Very negative. I’ve heard her speak and she tells of the probability of the Inuit way of life being extinguished due to the activities of people to the South, and NOT because of their own activities.)

    Talk to those who live on the coasts of Alaska by the Bering Strait and ask them how much their lives are improving. (They are not improving, but becoming increasingly threatened. Read Mark Lynas’ book “High Tide” for a story on Alaska and the Alaskan Aboriginals.)

    “Please provide the source for this scientific statement: ‘Also the 108.37 degrees was the climatic AVERAGE, not the high temperature on a day-to-day basis.’

    I am astonished to learn that the average climactic temperature has been so high without my having noticed it!”

    I was just quoting your post from earlier. It was if you had said New Delhi experienced 108.37 degrees instead of the 108 degrees from before climate change. I assume you made this scenario up, now.

  23. 73
    Eli Rabett says:

    This thread appears to be a fine example of putting your mouth where your money is not. Where are the bets? (who could resist?, feel free to trash this post)

  24. 74
    Mark Bahner says:

    I will be commenting much, much, MUCH more on the subject of “Betting on Climate Change,” as my free time allows. I’m currently working on posts for my own weblog, Roger Pielke’s “Prometheus,” and the Google alt.sci.environment discussion group.

    However, I’d like to address this issue:

    Glen Raphael commented (#61), “Bahner has officially posted a bet offer here. His prediction is that “the actual warming of the lower troposphere from 1990 to 2100, as measured by satellites, will be less than 1.94 degrees Celsius.” Splitting the difference between Michael Crichton’s prediction and one interpretation of the mean IPCC prediction.”

    William Connolley responded, “Bahner is weaselling, because his bet is only open “to members of IPCC” whatever that means.”

    I wonder why William Connolley didn’t go to the link Glen Raphael gave, and then go to the “Discuss this prediction” section? That would be the LOGICAL thing to do, if one had the question, “What does ‘members of the IPCC’ mean?”.

    [Response:You wonder why I didn’t follow a tedious chain of non-obvious links, when there was a big message stating very clearly “open to IPCC only?”. Oh come along – William]

    If William Connolley HAD gone to the bet discussion section, he would have seen this comment, which I posted two days ago (June 15):


    “When I made this bet, I stated that it was only open to ‘members of the IPCC.’ I meant ‘any authors of the IPCC Third Assessment Report (TAR).'”

    “However, when I wrote that, I thought that Gavin Schmidt and William Connolley of the website “Real Climate” were primary or secondary authors of the IPCC TAR. My understanding now is that Gavin Schmidt was not, and I don’t know about William Connolley. In any case, this bet challenge is specifically open to both of them. I am predicting that the warming of the globe, as measured by satellite measurements of the lower troposphere, will be less than 1.94 degrees Celsius. I challenge both of them to either agree or disagree with this prediction.”

    So there you have it. I specifically challenge you, William Connolley, to agree or disagree with my prediction. (If you disagree, I have $200–the minimum bet on “Long Bets”–that says I’m right and you’re wrong.

    [Response:Take away the “IPCC only” disclaimer: why are you so shy: James Annans bets are open to anyone. And clarify the satellite series, which vary by a factor of three: there are so many: by 2100 there will probably be even more. And pick a time horizon, like JA when we will still be alive: see – William]

    Of course, I can definitely understand if you’ll “weasel out,” William Connolley. After all, on your own blog, you point with pride to how high your blog comes up when one Googles the word, “Stoat.” (Here in the U.S., “stoats” are commonly known to be “weasels.”)

    [Response:Yes, stoats and weasels are very hard to distinguish. I’m very fond of both. Its a bit tricky when I use the word as an insult, because its simultaneously a term of endearment. I’m sure you can cope – William]

  25. 75
    Terry says:

    One way to solve this whole debate is to simply include the skeptic’s predictions into the IPCC range of predictions. Since the skeptics seem to be predicting around 0.6 degrees over 100 years (not too far below the current low end of the IPCC range), just make that the lower end of the range. Then, we have a “consensus” which runs from 0.6 degrees to the upper limit of the IPCC range.

    The skeptic’s estimate is based on a simple extrapolation from the recent trend. This is a straightforward model that seems to be within reason. I, personally, don’t see any reason to exclude it from the set of predicitons.

  26. 76
    Mark Bahner says:

    In comment #65, “Dano” writes, regarding my bet challenge on Michael Chrichton vs the IPCC:

    “Glen, that’s an old bet.”

    It’s only “old” in the sense that I made it many months ago. But it’s still BRAND NEW in the sense that no IPCC TAR primary or secondary author has stepped forward to accept my challenge.

    And it’s particularly new, in the fact that I made clear two days ago that the bet is SPECIFICALLY open to William Connolley and Gavin Schmidt.

    Dano continues, “We want Bahner’s answer to James.”

    All in good time, my pretty. All in good time. I have other work to do.

  27. 77
    Henry Molvar says:

    Thanks to James Annan for this post and to all who have commented. This truly clarifies many issues that were troubling me. What I find here is:
    1) Climate scientists and skeptics (some of whom are climate scientists) agree that global surface temperatures are rising.
    2) Both also agree on the approximate rate of increase and the projected approximate rate of increase over at least the next few decades.
    3) The only influential skeptic who falls outside 1) and 2) is Michael Crichton who, I contend, doesn’t have any actual beliefs regarding GW. He states his “beliefs” in order to promote his book(s) and movie(s) through whatever controversy that he can generate.

  28. 78
    Michael Jankowski says:


    “This statement is utterly ridiculous!”

    Which part – the deaths saved to hypothermia, or the idea that the colder, drier air masses warm first and the most? I think the latter is well agreed upon by both sides of the AGW argument. As for the former…

    “Those who live in these colder climate regions have adapted and really have little chance of dying of hypothermia and frostbite.”

    Not that simple according to the CDC : ***…the highest hypothermia-related death rates in the United States occur in northern states, where winter is characterized by moderate to severe cold temperatures (e.g., Alaska and Montana)…”

    And can we not adapt to warmer temps, too? See Davis, R.E., et. al., 2003, “Changing heat-related mortality in the United States, Environmental Health Perspectives.” You’ll see that “excess summer mortality rates” (the same thing used to quantify the deaths in Europe you spoke of) in 28 US cities had dropped in the 90s to 25% of what it was back in the 60s. And the 90s were the “hottest decade of the century” (or “all-time,” according to some) while the 60s were much cooler.

    “Look at the heat wave in Europe a summer or two again. That is what is happening and will likely get worse. Tens of thousands died there from the heat.”

    For starters, you’re linking that summer heat wave to GW, which very well could be a stretch and the kind of thing a previous poster was arguing against. Night and winter temps should be showing the greatest increases, not summer daytime temps. Secondly, shouldn’t Europeans be “adapted” to hot summers by now, just like the people in cold climates are (according to you) adapted to cold weather? Lastly, how about these tens of thousands? ***Exposure to cold is estimated to cause 30,000 deaths a year in the UK.***

    You also need to note exactly how that “tens of thousands” number was calculated for the European heat wave. The vast majority of those deaths were not directly attributed to the heat – they were tallied based on the difference in mortality from that summer to the previous one. The method is spelled out in this link Note that Germany and Spain, which had not yet applied that methodology, had recorded a very small amount of heat-related deaths.

  29. 79
    Brian S. says:

    It’s worth pointing out that Mark Bahner offerred the CO2 bet to Annan, Annan accepted the offer, and now Bahner is playing games as to whether a bet has been made. In this context Bahner should be extremely careful about throwing the word “weasel” around, as it is very close to hitting himself in the face.

    Several more days without an affirmation from Bahner, and we can say he does not stand by his bets.

  30. 80
    Jeffrey Davis says:

    The kinds of bets being proposed are a kind of conspicuous consumption: none of us will be alive to witness the outcome of bets due in 2100. It’s doubtful even if the escrow agent would exist or paperwork survive. To make a bet like this is simply to demonstrate that one has extra cash.

    Congratulations on having enough cash to light your stogies with.

  31. 81
    Mark Bahner says:

    Brian S. writes, “It’s worth pointing out that Mark Bahner offerred the CO2 bet to Annan, Annan accepted the offer, and now Bahner is playing games as to whether a bet has been made.”

    You’re “pointing out” something that is completely FALSE.

    Here is what I actually wrote on my weblog (Proposed bets for James Annan, Regarding IPCC TAR

    “Methane concentrations: The methane atmospheric concentration in 1990 was approximately 1700 ppb. The IPCC TAR projects a 50 percent chance that the methane atmospheric concentration will be more than 2060 ppb in 2030. That is obvious nonsense. In fact, if the atmospheric methane concentration is more than 2060 ppb in 2030, I will give you $50. But if it’s less than 2060 ppb, you give me $1. In other words, I’m giving you 50-to-1 odds on something that, if the IPCC TAR was correct, should be even money!

    Industrial emissions of CO2: Industrial emissions of CO2 in 1990 were approximately 6.0 gigatons as carbon. The IPCC TAR projects a 50 percent chance that emissions will be more than 13.2 gigatons as carbon in 2030. If emissions are more than 13.2 gigatons as carbon, I will give you $25. If they are less, you give me $1. In other words, I’m offering you 25-to-1 odds on something that, if the IPCC TAR was correct, should be even money.

    CO2 concentrations: The CO2 atmospheric concentration in 1990 was approximately 354 ppm. The IPCC TAR projects a 50 percent chance that the CO2 atmospheric concentration will be more than 438 ppm in 2030. If the CO2 atmospheric concentration is more than 438 ppm in 2030, I will give you $25. If the CO2 atmospheric concentration is less than 438 ppm in 2030, you give me $1. Again, I’m offering you 25-to-1 odds on something that, if the IPCC TAR was correct, should be even money.”

    In other words, I offered bets to James Annan on methane atmospheric concentrations, CO2 emissions, and CO2 atmospheric concentrations. ALL those bets would be viewed as giving James Annan EXTREMELY favorable odds, if the IPCC TAR projections were reasonable (which the most certainly are NOT).

    As everyone can see from the last paragraph quoted above, I offered James Annan ***25-to-1*** odds in his favor on something that SHOULD be, if the IPCC TAR projections were legitimate (which they are not) a 50/50 bet!

    By the way, my estimation of the IPCC TAR midpoint CO2 concentration in 2030 was based on the general method followed by Wigley and Raper to get the “50 percent probability” temperature increase in 2030 (relative to 1990), of 0.80 degrees Celsius. Anyone interested can see the IPCC TAR CO2 projections for the various scenarios here:

    IPCC TAR Summary for Policy Makers, Figure 5

    James Annan accepted that offer…if the CO2 atmospheric concentration is below 438 ppm in 2030 (which there’s approximately a 96 percent chance it will be, in my opinion), then James Annan will pay me $1. If the CO2 atmospheric concentration is above 438 ppm in 2030, I will pay James Annan $25.

    James Annan did have one question as he agreed to the bet. He asked if the results would be judged based on CO2 measurements at the Mauna Loa volcano in Hawaii?

    That is fine with me: CO2 concentrations at Mauna Loa, Hawaii, by CMDL

    The concentration for 2030 will be the average concentration over the entire year, assuming this is acceptable to James Annan.

    So James Annan and I definitely have a bet. If the CO2 concentration at Mauna Loa, averaged over the year 2030, is greater than 438 ppm, I will give him $25. Once again, I will give him ***25-to-1 ODDS*** on something that, if the IPCC TAR projections were correct, should be only even money.

    P.S. To my knowledge, James Annan has never accepted the ***50-to-1*** odds I gave him on the IPCC TAR’s midpoint 2030 atmopheric methane concentration.

    And he has never accepted my 25-to-1 odds on the IPCC TAR’s midpoint 2030 industrial CO2 emissions level.

    That kind of makes me wonder if Mr. Annan is being completely honest when he says he thinks the IPCC TAR projections are good. (Especially since I already know that they are not.)

  32. 82
    dave says:

    Could someone (Gavin?) relate these bets about warming by 2030 to the climate system’s inertia (warming lags) with respect to forcing as described in Earth’s Energy Imbalance: Confirmation and Implications by Hansen et. al. 2005. Here’s the quote:

    The lag in the climate response to a forcing is a sensitive function of equilibrium climate sensitivity, varying approximately as the square of the sensitivity, and it depends on the rate of heat exchange between the ocean’s surface mixed layer and the deeper ocean. The lag could be as short as a decade, if climate sensitivity is as small as 0.25C per W/m2 of forcing, but it is a century or longer if climate sensitivity is 1C perW/m2 or larger. Evidence from Earth’s history and climate models suggests that climate sensitivity is 0.75 to 0.25C per W/m2, implying that 25 to 50 years are needed for Earth’s surface temperature to reach 60% of its equilibrium response.

    We investigate Earth’s energy balance via computations with the current global climate model of the NASA Goddard Institute for Space Studies (GISS). The model and its simulated climatology have been documented, as has its response to a wide variety of climate forcing mechanisms. The climate model’s equilibrium sensitivity to doubled CO2 is 2.7C (~2/3C per W/m20.

    Now, suppose we stop all forcings now, taking equilibrium response at 380ppm C in the atmosphere plus the other GHGs. We still have 0.6C warming in the pipeline. Suppose further that 60% of that warming is manifest after 25 years (we’re at 2030) using the low estimate from the quote. That is 0.36C warming over the next 25 years and works out to 0.144C/decade. Now, this is obviously unreasonable since we’ve used the low estimate. Using the high estimate we could say that 60% of the pipeline warming is manifest after 50 years, yielding 0.36 warming over 50 years yielding 0.072C/decade over that period and 0.175C by 2030.

    Now, obviously GHG emissions are continuing to rise and the current decadel increase is 0.17 C reflecting an on-going transient response to increasing GHG levels in the past.

    I know that these calculations are naive, but how could anyone possibly think that we would not reach 0.30/C in twenty years?

    [Response: Well someone could claim that the model, the current radiative forcing and the ocean heat content changes they were validated against are all wrong, but I basically agree with your calculations – the current imbalance and the warming ‘in the pipeline’ imply even in the absence of further emission increases temperature trends are unlikely to be much below your estimate, (although you have to allow for some potential solar/volcanic/intrinsic variability). -gavin]

  33. 83
    Glen Raphael says:

    By that argument the Kyoto accord is also a kind of conspicuous consumption: none of us will be alive to witness the outcome of that bet either.

    To make a hundred-year bet is to demonstrate confidence in the continued viability of human institutions. If you don’t live long enough to collect, you can still sell your position to somebody else at whatever seems an appropriate price. If it starts tending to look like you’ll win, the value of the bet will increase over time. If not, not.

  34. 84
    Lynn Vincentnathan says:

    RE #48, you mention that the difference between 108 & 108.7 F in Delhi is not so great, but we need to understand that while temperature may increase incrementally, the damage due to GW may not follow a linear or incremental function. For instance, the last few inches added from a flood that breaches a levy and floods a huge metropolitan area are much worse than the first few inches from that flood. Likewise, the last .07 F increase in temp may cause a lot more heat deaths than the first .7 increase (say from 92 to 92.7 F). And the ice shelf break off is very sudden compared to the slowly rising temps.

    In the 70s I read about “catastrophe theory” in math. Perhaps that could be applied to GW damage scenarios. I remember seeing a potato chip function – I think meaning that you increase X just a bit more, & Y goes haywire.

  35. 85

    A small correction to the post by “Doug,” who wrote:

    “If alarmists are 95% confident that the IPCC temperature range encompasses the likely possibilities,”

    Such people, of course, are “scientists,” not “alarmists.” To qualify as an alarmist you’d have
    to believe in something ridiculous, like a 50% chance of a Venus-type runaway greenhouse, or
    the supposition that adhering to Kyoto would bankrupt the US economy.

  36. 86
    Joel Kuni says:

    In his Response appended to #47, William wrote:

    “As of 150 years ago, the thousand-year trend was downwards if anything: . If you believe in random natural shifts, you presumably believe they are as likely to be downwards as upward. “

    There’s no article in the link when I click it. Did you mean to give a different link?

    With regard to your second question, I am aware the trend of the past few years is upward. Why would I want to wager that the trend will not continue upward? I think the geologic record demonstrates that CHANGES in trends are infrequent and are therefore unlikely to occur in my lifetime.

    [Response:The link is correct and works (…ah. Now. It was correct when I pasted it in, but evidently WordPress is not smart enough to exlcude trainling periods from URL-ification). If you follow it, you’ll find a pic showing… that changes in the trends do indeed occur – William]

  37. 87
    SteveF says:

    I’d say the record for the late Pleistocene demonstrates repeated changes in overall trends. Take the various late glacial climate changes; the Bolling-Allerod and the Younger Dryas in the warming from the LGM. Or in the cooling towards the LGM there were the Dansgaard-Oeschger fluctuations.

  38. 88
    DrMaggie says:

    Re #86:

    I believe the link contains a spurious period at the end, e.g. it should actually read !

    [Response: Thanks. All previous links have now been fixed. – gavin]

  39. 89
    Stephen Berg says:

    A report about desertification as a result of climate change and unsustainable development:

  40. 90
    Steve Latham says:

    This is mostly for Joel Kuni but I’d like to solicit a comment or two from a RealClimate climatologist and a skeptical climatologist. The most relevant posts are #s 20 (JK), 40 (me), 47 (JK), 53 (Mike Jankowski), 54 (Joel Shore), 68 (JK), and 86 (JK).

    Dear Joel, I really think you are being disingenuous here. When asked why you think that a null hypothesis regarding non-anthropogenic-GHG forced temps should include continued increases, you have responded that (a) poorly understood fast termperature increases have occurred at the ends of ice-ages, (b) compared to the last several billion years, recent temperatures aren’t very high, and (c) temperature trends don’t change frequently, so you should not expect another change in your lifetime. I guess in response I should say (a) poorly understood rapid declines in temperature have also occurred (could you find a citation for rapid warming during an interglacial?); (b) some skeptics deride paleoclimatological data in support of worrisome GHG (+’ve feedbacks) but here you’re claiming support from estimates of temperatures a billion years ago; and (c) I have seen skeptical comments in the media that it was hotter in the ’30s, there was a global cooling scare in the ’70s, and we’ve been in a cooling phase since 1998 — these don’t jive with your assessment of trends. Okay, I know that my criticisms rely on others’ words, and truthfully I doubt the helpfulness of further explanation of why you don’t expect a return to recent mean temperatures (although I wouldn’t mind seeing more on your definition of a trend). Instead I’d like to use your comments in responding to your bet proposal.

    In #68, you say that you would need to see a statistically significant positive slope for temperature over the next number of years AND a model correspondence of 50%. I think it’s silly to demand an arbitrary r^2=0.50. Also, why focus on one part of the globe when we’re talking about global warming, and why focus on Antartica when the IPCC models suggest relatively little warming there? Instead what you (and the skeptic crowd in general) need to do is generate your own model for climate change that excludes positive forcings by anthropogenic GHG. Then that model or a family of them have to be run against IPCC models over a period of time so that the two can be compared to see whether including anthropogenic-GHG information adds to predictive or explanatory power. This suggestion relates to a general complaint I made in #28 here ( As of now I would presume that your model predicts a continuing monotonic increase in temperature at the same rate as has been occurring since the current warming “trend” began (please define “trend”), with a stochastic annual variance about that trend as estimated for the last billion years or so. Alternatively, you could adopt as your model an IPCC model with anthropogenic forcings due to GHGs zeroed-out (force-fit to historic data for the recent “trend” to re-calibrate the other forcings) and carried on into the future. I don’t expect that either model is a horse you’d bet on, but that’s really the kind of thing I think the skeptics need to provide. I reckon that if you can’t predict or explain climate change at least as well as the IPCC, then you should shut up about how bad the IPCC predictions are. The proof isn’t in the money you put up for silly bets and it’s not in how loudly you object “I’m not convinced!” — it’s in the abilities of an alternative model.

    Prior to Joel Kuni’s rebuttal, perhaps a RealClimate climatologist who understands these models could comment on errors I’ve made in my conjecture regarding climate models. My being inaccurate or stupid won’t advance the debate, but perhaps there is the germ of a valuable statement here that can be confirmed. Likewise. because demonstrating Joel’s position to be ridiculous would also accomplish little (his views seem extreme relative to most skeptics’ views presented here), perhaps one of the participating skeptical climatologists could also comment and educate me on whether this argument is relevant at all to most skeptical climatology.

    [Response:JK said since global warming models uniformly predict that the greatest anthropogenic warming will occur in the winter months in the driest, coldest climates. This appears to be a common illusion. I don’t know of any evidence for it. As you point out, the models don’t show a great deal of warming there. In fact, the models show (broad brush here) the greatest warming where the ice-albedo feedback is most active, ie in regions of seasonal snowcover or seaice.]

    [Response:As to predictions, JKs favoured “model” now appears to be… current trends will continue. Disregarding his reasonning (which I think is wrong) this is nonetheless a simple easy-to-use model, which can either predict global or local (if you chose to use it that way) temperatures. Run globally, it produces results compatible with the IPCC range, though towards the low end, so we have (yet again) the skeptics agreeing with the IPCC results (if not the method of obtaining them). Run locally, I suspect it would be quite wrong – William]

  41. 91
    Michael Jankowski says:


    If a skeptic chalks up most of the 20th century change to “natural variability” (as it seems the IPCC did with the warming of the first half the century),

    [Response:This is wrong. Read what they say: Simulations of the response to natural forcings alone (i.e., the response to variability in solar irradiance and volcanic eruptions) do not explain the warming in the second half of the 20th century. However, they indicate that natural forcings may have contributed to the observed warming in the first half of the 20th century. NF “may have contributed” is a long way away from chalking up most of it to NF – William]

    then it’s hard for one to come up with a model for future temps.

    [Response:No not really. If your postion is that nat var causes most of the changes, then you are in a position to predict that warming is as likely as cooling (or poss that cooling is *more* likely, if you regard the current warming as unusual). At one point, this appeared to be Lindzens position, but now we discover its not – William]

    And the skeptical position of many is that trying to model our climate system to any level of accuracy 10, 20, 50, or 100 years down the road is a fruitless exercise in itself. I do feel certain that if you (or someone else) were to establish a research facility/program for the purpose of creating and maintaining such models, you would have no trouble finding people to fill positions.

    You have some good points, but this is bogus: “I reckon that if you can’t predict or explain climate change at least as well as the IPCC, then you should shut up about how bad the IPCC predictions are.”

    When I had some work done on my driveway years back, the finished product had several problems that justifiably required correction (even as admitted by the contractor). Now I can’t tell someone how to pave a driveway, nor can I do it myself (beyond something not fit to look at or drive/park on). By your logic, I should’ve just shut-up about it. Was I in the wrong for complaining and having the work re-done properly?

  42. 92
    Joel Kuni says:

    Re #90,

    Steve wrote:

    “you have responded that (a) poorly understood fast termperature increases have occurred at the ends of ice-ages, (b) compared to the last several billion years, recent temperatures aren’t very high,”

    With all due respect, no, I didn’t. The link I provided describes a multitude of warming events that were not caused by humans, and not all of them coincided with the end of an ice age.

    Furthermore, I don’t recall ever writing a statement similar to your item (b) (did I?) but I think it’s interesting that the above link contains this information:

    ” Following the sudden ending of the Younger Dryas, about 11,500 years ago (or 10,000 14C years ago), forests quickly regained the ground that they had lost to cold and aridity. Ice sheets again began melting, though because of their size they took about two thousand more years to disappear completely. The Earth entered several thousand years of conditions warmer and moister than today; the Saharan and Arabian deserts almost completely disappeared under a vegetation cover…”

    Is this the terrible consequence of global warming we’re supposed to fear? That the Saharan desert might disappear under a vegetation cover?

    You asked if I can find a citation for rapid warming during an interglacial. The same source cited above provides a good one:

    “A particularly widespread cool event associated with relatively wet conditions seems to have occurred in many parts of the world around 2600 years ago (van Geel et al. 1996). A general pattern in climate during the Holocene has been detected from high-resolution cores in the north Atlantic. It seems that at least in the North Atlantic region, and possibly globally, there was a warm-cold cycle with a periodicity of around 1500 years (Bond et al. 1997). In the north Atlantic region, and probably adjacent oceanic areas of Europe, the change from peak to trough of each period was about 2 deg.C , a very substantial change in mean annual temperature (though only a small fraction of the change between glacial and interglacial conditions).”

    My choice of Antarctica for a region to study was made because I am attempting to focus on the regions of the earth that should be warming fastest, if the IPCC models are correct. The models uniformly predict that the greatest anthropogenic warming should occur in the winter months in the driest, coldest climates of the globe. Wintertime in Antarctica seems to fit this description perfectly. If the models cannot explain the climate in Antarctica, then I think we have to seriously question their validity and all the conclusions drawn from them.

    I am surprised by your assertion that “the IPCC models suggest relatively little warming” in Antarctica. This is news to me. Please provide your source. I am eager to correct my misconceptions.

    [Response:Are you really? How nice. And yet, you’ve been told something quite directly, and still haven’t bothered to look it up, nor can you be bothered to cite the sources of your misconceptions. If you want to know about the IPCC TAR projections of future climate, then a good place to look might be… the IPCC TAR: . The rest of your post is similarly littered by misconceptions, which people have corrected you on, but I rather doubt you’re going to listen or learn – William

    My choice of r-squared=50% was not arbitrary. If nobody is willing to wager on a value this high, then we can probably make the following statement, which I think will come as a gigantic shock to most of the general public and the reporters who pander to them:

    Climatologists are in unanimous agreement that the link between greenhouse gasses and temperatures is so weak that less than half the changes in the earth’s climate can be attributed to mankind’s emissions of greenhouse gasses.

  43. 93
    William says:

    A reminder re the comment policy: pure economics is out. We’re fairly flexible about this but a line has to be drawn somewhere. Repetetive long comments are also at risk – William

  44. 94
    Dano says:

    Since the poster didn’t do so in #92, can anyone provide a link to the shocking, likely untrue phrase Climatologists are in unanimous agreement that the link between greenhouse gasses and temperatures is so weak that less than half the changes in the earth’s climate can be attributed to mankind’s emissions of greenhouse gasses.?

    Has Arrhenius been audited and found wrong?

    Thank you in advance,


  45. 95
    Michael Jankowski says:

    Re#91 William,

    Yes, it does say that in the TAR (I guess I was using the ’94 SAR interpretation), but there are points throughout the TAR that I think conflict with that statement. It will take some time and length for me to find them and present them.

    As far as your comments with the model issue and 50/50 cooling vs warming idea, I addressed those in another post. But to repeat: if a skeptic believes we are still recovering from the last ice age (or at least the LIA), or at least believes we are in a naturally warm cycle that may not completely reverse itself back to current temps within the next 20 yrs, then a skeptic would not take a flat wager on cooling from 2005-2025. To repeat another point (in case it has arisen again): what you or a non-skeptic thinks about the LIA being a regional phenomenon and/or 20th century being unnatural warm is not necessarily what a skeptic believes. A skeptic would base his/her wager accordingly.

  46. 96
    SteveF says:

    r.e. post #32.

    Just a quick point, but the greening of the Sahara wasn’t the result of a warming climate. Rather it was the result of the particular orbital configuration during the early-mid Holocene and a bunch of other processes (not yet fully understood) including land surface feedbacks and the effect of the adjacent ocean.

    Also, with regards to warming in the interglacial, the notion of Holocene stability is indeed something of a myth. It mainly derives from the lack of action (8.2 ka event aside) in the ice cores and as ice core results are pretty trendy and have a large say (rightly so) in directing research questions, a lot of people think of the Holocene as kind of boring. The Bond paper is cited all over the place, however on land these periodicities haven’t really been replicated and I’m not sure if they have been fully replicated in the oceans either. Climate changes (precipitation more significantly than temperature) have undoubtedly occurred in the Holocene though.

  47. 97
    SteveF says:

    r.e. #95,

    I sincerely hope that no reasonably well informed skeptic has ever said that recovering from an ice age could be an explanation for what we are currently seeing. If they have, please post a link so that I can laugh at them.

  48. 98
    Michael Jankowski says:

    Re#94 Dano,

    Not the same, but the following TAR statement doesn’t seem that far off to me with regard to temperatures:

    “In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations.”

    Most people would translate that to indicate that the IPCC is saying there’s >50% chance that >50% of the warming of the last 50 years is due to increasing GHG concentrations, but it depends on what your interpretation of the words “likely” and “most” are. The link between GHG concentrations and the warming of the 1st half of the 20th century is almost certainly weaker, is it not? So it isn’t that much of a stretch to thereby say the IPCC cannot conclusively attribute over 50% of the 20th century temperature rise to anthropogenic GHG emissions – and that’s just the 20th century.

    And, of course, the original post says, “changes in the earth’s climate,” which may not necessarily only be referring to temperature.

    [Response:You are making what I think is a common mistake – to assume that anything not definitively attributed to GHG is attributed to something else. Thats wrong. The TAR, as I (and now, it seems, you) read it, attributes last-50-y to GHG’s, mostly. But fo the first 50 y, attribution statements are much weaker. A mixture of various forcings could be at work and its rather hard to disentanlge them. But there is nothing in there (AFAIK) that says “we can definitively exclude GHG’s as the major contributor to the warming in the first half of the 20th C” – William]

  49. 99
    Michael Jankowski says:

    RE#98 William,

    I didn’t “assume that anything not definitively attributed to GHG is attributed to something else.” That is not part of #92, #94, or #98. The question was whether or not half of “climate change” could be attributed to GHG. I just pointed out that even the IPCC couldn’t definitively say that over half the warming of the latter part of the 20th century was due to anthropogenic GHGs, and that figure would certainly be lower for the 1st part of the 20th century, along with certainly the vast majority of temperature changes prior to the 20th century. I think this is along the lines of what was said in #92.

    ***But there is nothing in there (AFAIK) that says “we can definitively exclude GHG’s as the major contributor to the warming in the first half of the 20th C***

    There is also nothing that says GHG’s were the major contributor to the warming in the first half of the 20th century, and my post #98 (and the original post of #92) was concerned with only how much was attributed to GHGs. If you’re going back to what I said in #95, I’ll repeat that I have to set aside time to go thru the TAR and pick-out the conflicting information.

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    Eli Rabett says:

    WRT the back and forth between William and Michael, I think we are into defining levels of proof rather than discussing science. While this is not science, but law, the levels of proof in the law form a useful construct for analyzing the situation. In the US these are reasonable suspicion, probable cause, preponderence of the evidence, clear and convincing, and beyond reasonable doubt. There are some explanations of these terms at although most probably have a good idea. WRT the reality of significant and increasing human driven climate change the question is where on this scale are you, and where do you think the IPCC is. I’m at clear and convincing and I think that is where the IPCC is. I should point out that this is the level of proof required in a child custody cases. Given that we are responsible for the Earth, it is appropriate.