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The Global Cooling Bet – Part 2

Filed under: — group @ 13 May 2008 - (Italian) (Deutsch) (Español)

Last week we proposed a bet against the “pause in global warming” forecast in Nature by Keenlyside et al. and we promised to present our scientific case later – so here it is.

This is why we do not think that the forecast is robust:

Fig. 4 from Keenlyside et al '08

Figure 4 from Keenlyside et al ’08. The red line shows the observations (HadCRU3 data), the black line a standard IPCC-type scenario (driven by observed forcing up to the year 2000, and by the A1B emission scenario thereafter), and the green dots with bars show individual forecasts with initialised sea surface temperatures. All are given as 10-year averages.

  1. Their figure 4 shows that a standard IPCC-type global warming scenario performs slightly better for global mean temperature for the past 50 years than their new method with initialised sea surface temperatures (see also the correlation numbers given at the top of the panel). That the standard warming scenario performs better is highly remarkable since it has no observed data included. The green curve, which presents a set of individual 10-year forecasts and is not a time series, each time starts again close to the observed climate, because it is initialised with observed sea surface temperatures. So by construction it cannot get too far away, in contrast to the “free” black scenario. Thus you’d expect the green forecasts to perform better than the black scenario. The fact that this is not the case shows that their initialisation technique does not improve the model forecast for global temperature.
  2. Their ‘cooling forecasts’ have not passed a the test for their hindcast period. Global 10-year average temperatures have increased monotonically during the entire time they consider – see their red line. But the method seems to have produced already two false cooling forecasts: one for the decade centered on 1970, and one for the decade centered on 1999.
  3. Their forecast was not only too cold for 1994-2004, but it also looks almost certain to be too cold for 2000-2010. For their forecast for 2000-2010 to be correct, all the remaining months of this period would have to be as cold as January 2008 – which was by far the coldest month in that decade thus far. It would thus require an extreme cooling for the next two-and-a-half years.
  4. Even for European temperatures (their Fig. 3c, not part of our proposed bet), the forecast skill of their method is not impressive. Their method has predicted cooling several times since 1970, yet the European temperatures have increased monotonically since then. Remember the forecasts always start near the red line; almost every single prediction for Europe has turned out to be too cold compared to what actually happened. There therefore appears to be a systematic bias in the forecasts.
  5. One of the key claims of the paper is that the method allows forecasting the behaviour of the meridional overturning circulation (MOC) in the Atlantic. We do not know what the MOC has actually been doing for lack of data, so the authors diagnose the state of the MOC from the sea surface temperatures – to put it simply: a warm northern Atlantic suggests strong MOC, a cool one suggests weak MOC (though it is of course a little more complex). Their method nudges the model’s sea surface temperatures towards the observed ones before the forecast starts. But can this induce the correct MOC response? Suppose the model surface Atlantic is too cold, so this would suggest the MOC is too weak. The model surface temperatures are then nudged warmer. But if you do that, you are making surface waters more buoyant, which tends to weaken the MOC instead of enhancing it! So with this method it seems unlikely to us that one could get the MOC response right. We would be happy to see this tested in a ‘perfect model’ set up, where the SST-restoring was applied to try and get the model forecasts to match a previous simulation (where you know much more information). If it doesn’t work for that case, it won’t work in the real world.
  6. When models are switched over from being driven by observed sea surface temperatures to freely calculating their own sea surface temperatures, they suffer from something called a “coupling shock”. This is extremely hard, perhaps even impossible, to avoid as “perfect model” experiments have shown (e.g. Rahmstorf, Climate Dynamics 1995). This problem presents a formidable challenge for the type of forecast attempted by Keenlyside et al., where just such a “switching over” to free sea surface temperatures occurs at the start of the forecast. In response to the “coupling shock”, a model typically goes through an oscillation of the meridional overturning circulation over the next decades, of the magnitude similar to that seen in the Keenlyside et al simulations. We suspect that this “coupling shock”, which is not a realistic climate variability but a model artifact, could have played an important role in those simulations. One test would be the perfect model set up we mentioned above, or an analysis of the net radiation budget in the restored and free runs – a significant difference there could explain a lot.
  7. To check how the Keenlyside et al. model performs for the MOC, we can look at their skill map in Fig. 1a. This shows blue areas in the Labrador Sea, Greenland-Iceland-Norwegian Sea and in the Gulf Stream region. These blue areas indicate “negative skill” – that means, their data assimilation method makes things worse rather than improving the forecast. These are the critical regions for the MOC, and it indicates that for either of the two reasons 5 and 6, their method is not able to correctly predict the MOC variations. Their method does show skill in some regions though – this is important and useful. However, it might be that this skill comes from the advection of surface temperature anomalies by the mean ocean circulation rather than from variations of the MOC. That would also be a an interesting issue to research in the future.
  8. All climate models used by IPCC, publicly available in the CMIP3 model archive, include intrinsic variability of the MOC as well as tropical Pacific variability or the North Atlantic Oscillation. Some of them also include an estimate of solar variability in the forcing. So in principle, all of these models should show the kind of cooling found by Keenlyside et al. – except these models should show it at a random point in time, not at a specific time. The latter is the innovation sought after by this study. The problem is that the other models show that a cooling of one decadal mean to the next in a reasonable global warming scenario is extremely unlikely and almost never occurs – see yesterday’s post. This suggests that the global cooling forecast by Keenlyside et al. is outside the range of natural variability found in climate models (and probably in the real world, too), and is perhaps an artifact of the initialisation method.

Our assessment could of course be wrong – we had to rely on the published material, while Keenlyside et al. have access to the full model data and have worked with it for months. But the nice thing about this forecast is that within a few years we will know the answer, because these are testable short term predictions which we are happy to see more of.

Why did we propose a bet on this forecast? Mainly because we were concerned by the global media coverage which made it appear as if a coming pause in global warming was almost a given fact, rather than an experimental forecast. This could backfire against the whole climate science community if the forecast turns out to be wrong. Even today, the fact that a few scientists predicted a global cooling in the 1970s is still used to undermine the credibility of climate science, even though at the time it was just a small minority of scientists making such claims and they never convinced many of their peers. If different groups of scientists have a public bet running on this, this will signal to the public that this forecast is not a widely supported consensus of the climate science community, in contrast to the IPCC reports (about which we are in complete agreement with Keenlyside and his colleagues). Some media reports even suggested that the IPCC scenarios were now superseded by this “improved” forecast.

Framing this in the form of a bet also helps to clarify what exactly was forecast and what data would falsify this forecast. This was not entirely clear to us just from the paper and it took us some correspondence with the authors to find out. It also allows the authors to say: wait, this is not how we meant the forecast, but we would bet on a modified forecast as follows… By the way, we are happy to negotiate what to bet about – we’re not doing this to make money. We’d be happy to bet about, say, a donation to a project to preserve the rain forest, or retiring a hundred tons of CO2 from the European emissions trading market.

We thus hope that this discussion will help to clarify the issues, and we invite Keenlyside et al. to a guest post here (and at KlimaLounge) to give their view of the matter.

198 Responses to “The Global Cooling Bet – Part 2”

  1. 51
    Paolo Morelli says:

    I’ve just finished reading an article in a popular Italian newspaper titled “The catastrophe of the catastrophists” in which the “pause in global warming” forecast in Nature is deliberately depicted as a terrible debacle for the community of climate scientists.
    Unfortunately we don’t have resources like Real Climate in our own language to question such silly arguments and a lot of people will just believe what they read in the newspaper. Quite sad..

  2. 52
    Jim Cripwell says:

    Ref 50 Peter Johns asks “Why did GISSTEMP for March fall from 0.81 deg to 0.68 deg?
    This makes the first 4 months of 2008 the coolest since 2000.” Presumably because that is what actually happened; the “measured” temperature for April 2008 was 0.68 C. If the satellite data reported daily for May is representative of GISTEMP, then the May figure will be around the same number.

  3. 53
    dhogaza says:

    Why did GISSTEMP for March fall from 0.81 deg to 0.68 deg?

    Actually it rose from 0.33C the month before to 0.68C.

    Is there any particular reason why you think comparing Feb ’07 with Mar ’08 is more valid than comparing Feb ’08 with Mar ’08?

    Is there any particular reason why you think such month-to-month comparisons are meaningful in the first place?

    Oh, and the question, Alex, is “What is La Niña”.

  4. 54
    Pebbles says:

    I never believed there would be a pause in global warming, thanks for your article about it.

    I have a nephew who is a student at Princeton University and he is pursuing a degree and career regarding how to save the planet from global warming problems. I’m going to email him the link to this blog. He might already have it, but I’m going to email it to him anyway.

    I just read a magazine article about how we could be getting fuel from algae, and be able to get rid of our dependence on fossil fuel. Wouldn’t that help to slow down the global warming?

    Thanks for the good work and the good fight!

  5. 55
    Nylo says:

    Re #45 Joel Shore: You are completely right. But that was not the point I was trying to make. As you say, the 3% should be, if anything, proportional to the second derivate of the concentration of CO2 in time. And that is what I addresed next. How could it be, that during the eighties and the nineties the emissions were growing at about a full 3% per year, and yet the second derivate of the concentration was 0 or slightly negative?

    My guess was that the rising temperatures did the miracle, and because they stopped rising in 2000, now the second derivate is positive. But in the eighties and the nineties, an improved response by the photosintesis of plant life due to increased temperatures would have been able to neutralise all of the extra emissions we were sending to the atmosphere with respect to the emissions of 1980, and becaue of that the increase in the concentration of CO2 (the first derivate) became constant (i.e. the second derivate was 0).

    Cobblyworlds in #26 suggested that the fact that we have more CO2 in the atmosphere has made the oceans be able to also keep more CO2, taking it from the atmosphere. He is right about the physics of the process. However I doubt that that is the real reason, for 2 things: first, the absolute change in concentration of CO2 was very little as to absorb that much; second, the ocean temperatures were increasing at the same time, which means they can absorb less CO2, because of another phenomenom called outgassing, which may well cancel or even override the first one. And third, we are still rising our emissions, the conentrations are still increasing, and it is like the ocean stopped absorbing CO2. Why? It makes no sense. The photosintesis hypothesis looks better correlated with the known events we are experimenting, and also has a well known physical process to support it.

    [Response: This is all very well, but wrong. You have to explain the O2 change (Keeling et al) and the d13C changes as well. They clearly point to the fact that the ocean has been the net sink for almost all the carbon (uptake by land in some areas is mainly balanced by deforestation in others). Plus we have direct inventories of ocean carbon that confirm the rise (see IPCC AR4 2.3.1). - gavin]

  6. 56
    Aaron Lewis says:

    re 32
    We could deal with one 800 pound Silverback in the room. The problem is that there are two big gorillas in the room – the other one is the ice sheets. Together, They are likely to cause quite a ruckus.

  7. 57
    Mark Sharkey says:

    I know climate science is complex but thinking about warming of a block of ice in a glass, the temperature increase will stall for a while at 0deg.C while the ice melts before taking off again. It could just be that the same thing is happening on a global scale.

  8. 58
    Ray Ladbury says:

    Mark Sharkey–Yes, the temperature IN THE VICINITY OF THE ICE stops rising. However, I would be reluctant to attribute a cold winter in Baghdad to melting ice at the poles. This is weather. The skeptics will continue to crow that warming stopped in 1998, just like they did in 1996 and 1993 and 1991… They will do so until the next big El Nino knocks us up to another record year, and when the following year is cooler than the record, they’ll say global warming stopped them. Hell, I’m surprized they don’t claim warming stops every winter just for the practice!

  9. 59

    #36, #11 etc. I’m not sure what your point is. Hearing the phrase “over 3%” in Boulder yesterday doesn’t contradict Gavin’s assertion: [Response: Emissions are rising 3% a year, concentrations at just over 0.5% a year (~2ppm). - gavin]

    You can easily discern the correct numbers with google.

    These numbers confirm that Gavin’s 3% for the emissions rate is correct.

    This site gives the growth rate in ppm:

    Typical annual increase is about 2 ppm/year.

    The CO2 concentration is about 380ppm. Thus the fractional increase is 2/380 = .005 = .5% as Gavin stated.

  10. 60
    Jared says:

    The April numbers are in from GISS and HadCRU.

    GISS: .51 anomaly. Dropped .17 from March. 2008 so far the coolest year globally since 2001.
    HadCRU: .25 anomaly. Dropped .18 from March. 2008 so far the coolest year globally since 1997.

    In addition, 2008 has been the coldest year in the U.S. since 1993.

  11. 61
    Hank Roberts says:

    > 3%, Richard Ordway
    It’d be interesting to know what source you were relying on when you wrote “evidence shows” — where did you get that? Link or cite? If it’s an error somewhere it’s worth correcting. If it was misread, that’d be useful to know.

  12. 62
    Nick dePalma says:

    I am an amateur at this subject but I keep up with this website and I admit I’m a partisan pro-climate changer. But I wanted to bring up a previous bet by a few russian scientists a few years ago claiming that there will be a pause as well (global cooling briefly) and then roaring back heating. Whatever happened to that bet ?

    Thanks :-P

  13. 63
    Chris says:

    Sir Gilbert Walker’s (“discoverer” of the Southern Oscillation) words seem apposite here with respect to short term predictions of “climate” and their value and the dangers of making predictions on unsubstantial grounds:

    Speaking (of the monsoon) at the 1930 meeting of the Royal Meteorological Society, Walker stated:

    “In general the object of prediction is to assist the layman, and it is the opinion formed by him that decides whether they will suceed or fail. Hence I regard it foolish to issue a prediction except in years when the indication for an excess or deficit [of rainfall] are so strongly marked as to give a 4:1 chance of success….and as the claim to “forecast” the seasons arouses the expectation of an annual precipitation, I advocate the word “foreshadow” as expressing a smaller ambition”

    Do Keenlyside consider their prediction to be a “forecast”….. or a “foreshadow”….?

    [Walker quotation from J. Madeleine Nash "El Nino: Unlocking the Secrets of the Master Weather-Maker" AOL-Time Warner 2002, p 45.....which is a very good read]

  14. 64
    dhogaza says:

    Gosh, Jared has discovered weather. Next think you’ll know, he’ll discover climate.

  15. 65
    Hank Roberts says:


    (I Googled: climate Russian scientists bet cooling
    and it popped right up.)

  16. 66
    Ray Ladbury says:

    #60. Golly, Jared, thanks for the weather report. Maybe there’s a domain name “realweather” and somebody will care there.

  17. 67
    Richard Ordway says:

    Hank Roberts Says:
    15 May 2008 at 4:00 PM
    > 3%, Richard Ordway

    [[It’d be interesting to know what source you were relying on when you wrote “evidence shows” — where did you get that? Link or cite? If it’s an error somewhere it’s worth correcting. If it was misread, that’d be useful to know.]]

    Hank, I’ll get their source…I need to know myself. I was out of the office today. It was from an in house presentation from a visiting scientist. Thank’s for reminding me.

    If I mistated it, I will gladly post that too. Like I said, any of the moderators can look up one of my two IP addresses and know where the source was. Speaking of which, finding out where I heard the original presenter speak, would probably take you about two minutes if you really wanted to.

  18. 68
    Richard Ordway says:

    Hank Roberts wrote:
    “where did you get that?”

    You could also look at the acknowlegements section of the book “Climate Change” by Bob Henson :)

  19. 69
    tharanga says:

    Unless I missed something, I’m not seeing anything as to whether your bet has been accepted. What’s the status?

    If nothing else, it would be nice if Keenlyside et al would come by here and post a response – I hope they are taking this in good spirit.

    This is turning into a nice demonstration of how blogs like this one can supplement comments and replies in the published literature – it’s fast, informal and more public.

  20. 70


    You know, when somebody introduces themselves as “veritas” or Mr. Friendly the used automobile salesman, I reflexively reach for my wallet.

    Reach for a bat instead.

    Responding to gavin’s response:

    This begs a question. Should you lose the bet, what ramifications does that have for AGW theory? How many years of cooling will it take before AGW theory is debunked? Let’s see a commitment from RC staff on this. How many years of continued cooling will it take for AGW theory to be rejected? You like bets, then place one on that.

    [Response: None. About 20. Like I said. Lot’s of bets have been offered - few taken. - gavin]

    Respectfully, I disagree. If we see — call it 3 to 5 years — a period of cooling that isn’t predicted by the same people predicting warming, any progress on reducing emissions will be lost and the consequences will be worse. After several warm winters and summers, most people I know that I talk to causally about global warming were “convinced”. Now, with two regular winters, a mild summer, and what looks to be another mild summer, the “it was a scam” drumbeat is growing.

    It’s like the stupid “Gasoline Tax Holiday” ideas being floated here in the States. The most direct measure we have of scarcity is cost, and cost needs to accurately reflect scarcity or people will forget it is “scarce”. Dropping the tax will increase consumption, and then when the poop really hits the propeller, things will be even worse.

  21. 71
    Peter Johns says:

    dhogdzha – March was initially 0.81 when first added 4 weeks ago but the Mrch figure decreased to 0.68 when the April data was added. I was talking March only, not the change from Feb to March.

  22. 72
    Nylo says:

    #55 (Gavin response): If photosinthesis is not the cause, why does it happen that the years in which CO2 concentration increases the most are years which are colder than the year before, independently of the changes in emissions? Also, why do you think that the ocean’s absorption of CO2 has reduced so much? We didn’t change too much the rate of increased emissions, but the rate of increase of CO2 concentration has raised a full 25% from the 90′s. Another thing, you make reference to O2 changes and d13C published somewhere. Is there a link I can follow to read that information?

    Thanks a lot.

  23. 73
    Ray Ladbury says:

    Furrycatherder, While a few years of cooling might change the urgency in the collective mind of the great unwashed, it will not change the science. Hell, the public mind changes with the weather–literally. Ultimately, it will come down to education. I am hoping that as climate models improve we’ll have a better fix on the realistic risks. I really believe that one of the things driving opposition to the science is uncertainty over what actions will be required to limit damage from climate change. Most people envision going back to the horse and buggy days, and they are understandably loathe to do that. I think that if we can come up with a concrete plan of action and show that it does not destroy the economy, we will win a lot more converts.

  24. 74
    B Buckner says:

    Ray #73, I agree with your post and the need to act without destroying the economy. One of the problems is that there are proposals from various state legislatures (US)and other organizations to reduce emissions by 80 percent by 2050 to stabilize CO2 levels. If you account for population growth between the baseline year of 1990 and 2050, you end up in 2050 with a per capita carbon footprint that gets us back to where we were in colonial times. So the horse and buggy days fear is not unfounded.

  25. 75
    Ray Ladbury says:

    B. Buckner, To claim that because we cannot burn fossil fuels, we cannot consume energy is a fallacy. With oil becoming ever more scarce, our energy consumption will have to change in any case. Adding climate to the equation eliminates coal as an option, but that is about all. I would claim that this is a problem that could have a technical solution–and technical solutions often have a way of finding applications that make the economy grow.
    The main problem is that we don’t know how close we are to various tipping points, so it makes sense to try to conserve as much as possible in order to buy time. The goal has to be sustainability, and sustainability is not incompatible with growth, as long as the growth comes via technological advance.

  26. 76
    CobblyWorlds says:

    #72 Nylo,

    If photoynthesis is the cause then why the change in isotope composition?

    A large part of the CO2 we emit is absorbed by the ocean and land biological processes. Any changes in either ocean (Weather/El Nino’s, circulation changes, etc) or land, (warmer/cooler or wetter/dryer years) will impact how much is taken up. That means the amount added to the atmosphere would vary even if we were emitting a constant amount each year. Actually we’re rapidly increasing emissions on a global basis.

    And on the subject of warm/cool or wet/dry years: The article by David Archer that I linked to discusses cases where average wind conditions have changed and this, not primarily temperature, has reduced CO2 uptake by the oceans.

    With regards an explanation of isotopes and how we know the CO2 increase is down to humans: Just click on Index at the top of this page, and scroll down to “Greenhouse gases:”, you need the second link down, entitled “How do we know that recent CO2 increases are due to human activities?”. It is not a coincidence that the article explains how we know the CO2 increase is due to human activity.

    #74 B Buckner,

    So the horse and buggy days fear is not unfounded.

    I think it is unfounded, personally I consider it a straw man.

    Based on those I know at work and socially, I consider it inherently improbable that you could get people to vote for a government that proposes such austerity. There are 2 reasons I have reduced my emissions: Because it’s the right thing to do and because it saves me money.

  27. 77
    Hank Roberts says:

    > finding out where I heard the original presenter speak
    Richard, that doesn’t matter, I’m just asking for a source for the number — ‘reference librarian’ not ‘private investigator’ question.
    Next time I see the number in someone’s blog, I’d like to point to a cite for it, not trying to blame it on anyone (grin).

  28. 78
    Richard Ordway says:

    Hi Hank,

    Here is the peer-reviewed reference from the National Academy (PNAS) on CO2 rising more than 3% per year:

    “CO2 emissions from fossil-fuel burning and industrial processes
    have been accelerating at a global scale, with their growth rate
    increasing from 1.1%/y for 1990–1999 to >3%/y for 2000–

    The emissions growth rate since 2000 was greater than for
    the most fossil-fuel intensive of the Intergovernmental Panel on
    Climate Change emissions scenarios developed in the late 1990s.

    ‡‡CO2 data are available at”

    Raupauch et al. PNAS 2007. “Global and regional drivers of accelerating
    CO2 emissions”

  29. 79

    77 Ordway’s original comment was bizarre: “Evidence shows that CO2 is going up at over 3% per year”

    since he doesn’t actually say what it is that he’s talking about. “CO2 is going up”? What is that supposed to mean? Up into the sky? Up in concentration? Up in rate of emission? In none of his subsequent remarks did he acknowledge that his original post was incoherent.

    if you want a source for Gavin’s numbers you can click on the links that I posted in 59 and you’ll find all the numbers you need to get an estimate that is in accord with Gavin’s claim of emissions rate increasing at 3%/year and concentration increasing at 0.5%/year.

  30. 80
    Hank Roberts says:

    There we go, it’s _emissions_ not _atmospheric_level_ going up at three percent, which does make sense.

    Illustrating why to state units when quoting digits (grin).

  31. 81
    John Bartlett says:


    Re #6,

    ‘RealClimate needs to be read by the whole world. You are often too mathematical for almost everybody. Your concepts are mathematical. Nonetheless, RealClimate should be what everybody reads directly for themselves, if they can.’

    I am about to set up a web site that, amongst other things, will report such things as Realclimate articles (with citation). The idea is that it will be aimed at a slightly less educated audience
    than this site. The web site exists but is currently private.

  32. 82
    Richard Wakefield says:

    Re 31: I assume that 20 years includes the previous 10 that has shown a flat temperature change, so on Jan 1, 2019 and the world has not heated up you will declare AGW theory false, right?

    Ok, so let’s add others to the mix. How many years of there not being any acceleration in the rate of sea level rise would it take to declare AGW theory false? To accommodate the IPCC the rate would have to increase 3-5 times the current 1.33mm/yr, the same rate it’s been for at least the last 110 years. Some of the more extreme increases would call for a rate increase of 30 to 40 TIMES the current rate. So, how many more years of flat rate will it take to abandon AGW theory?

  33. 83
    Ray Ladbury says:

    Richard Wakefield, What is it with the anti-science crowd and “falsification”? A failure of models to predict correctly does not necessarily mean the model is completely wrong. More likely, the model is incomplete. It neglects a factor that is important during the period under question. This factor may counter the anthropogenic hypothesis, or it may merely mask it for awhile. A Grand Solar Minimum, as many in the denialosphere are blogviating (btw, thanks to the RC folks for this term), does not mean that CO2 is unimportant, as it will kick in with a vengeance when the minimum ends. You guys really need to look into how science actually is done. There’s more to it than Karl Popper.

  34. 84
    Ed Davies says:

    Assuming, for the purposes of this question, that the Keenlyside et al paper is right so that there will be a pause in the rise of land and sea surface temperatures, am I right in thinking that this does not indicate a pause in global warming in that, during the pause in the rise in surface temperatures, the temperatures in the ocean below the surface layers would be increasing?

    If so, would such rises be very small compared with surface temperature rises? I’m thinking that they would be because of the huge thermal capacity of the ocean.

    Again if so, are ocean temperature measurements made with sufficient accuracy that such rises could be detected reliably?

  35. 85
    Jim Eager says:

    Re Richard Wakefield @82: What 10 year flat temperature change?
    I don’t see a ten year flat temperature change anywhere on that graph.

    Nor on this one

    As for your 1.33 mm/yr rate of sea level rise, you are woefully behind in your reading:;294/5543/840
    Even if entirely due to thermal expansion the current rate is almost double that.

    Not only do you guys really need to look into how science is actually done, you need to look into what the science actually says.

  36. 86
    Ray Ladbury says:

    Ed Davies, I think you are basically correct. The heat does not leave the system. However, the extent of the warming in the ocean depends on how much mixing (e.g. to what depth) occurs.

  37. 87
    Hank Roberts says:

    > falsification

    The physical theory and data collection can be falsified — that’s the individual pieces.

    A whole model can’t be falsified. Willy Ley once famously remarked that analysis is all very well, but you can’t figure out how a steam locomotive works by melting it down and analyzing the mess. You have to look at the pieces and test each one.

    Same thing when airplanes fall out of the sky. That doesn’t falsify aviation, or the particular airplane design, or flight in general.

    A repeated problem can falsify one component:

    “… The testing took months but finally identified the problem. The stresses caused by thousands of takeoffs and landings were causing the plane’s aluminum skin … to crack …. Eventually the metal would completely fail, causing immediate depressurization of the cabin and catastrophic structure failure….”

    That falsifies one design element, not the whole idea of flight.

    If a problem once identified fails to be understood, yes, later designs will have the same kind of failure:

    “… As the airplane leveled at 24,000 feet, both pilots heard a loud “clap” or “whooshing” sound followed by a wind noise behind them. The first officer’s head was jerked backward, and she stated that debris, including pieces of gray insulation, was floating in the cockpit. The captain observed that the cockpit entry door was missing and that there was blue sky where the first-class ceiling had been….”

    There is no such thing as a fail-safe design:
    “The Boeing 737 Classic was designed with a ‘fail-safe structure’…”

    Current aircraft use far more modeling in the design than the older ones. No one claims to be able to “falsify” computer models per se, or even individual models at a particular point in time.

    Well, no one who uses or understands them.

    So, see someone claiming some one fact can falsify a model, or modeling?

    Check their cites.

  38. 88
    gmb says:

    Re: 74

    To add to the other comments, the “horse and buggy” logic seems to go like this:

    1. Before fossil fuels, quality of life was lower (horse and buggy).

    2. Fossil fuels increased quality of life.

    3. Therefore, a strong move away from fossil fuels will return us close to (1).

    Problem is, in the horse and buggy days, we didn’t really have a great ability to capture wind and solar energy, among other things. There wasn’t the option of nuclear power. There was no such thing as EV or plug-in hybrids. Carbon sequestration wasn’t a possibility in the near future. There wasn’t a range of other options to make us more energy-efficient.

    Some technologies are already economically viable:

  39. 89
    wmanny says:

    #83 “A failure of models to predict correctly does not necessarily mean the model is completely wrong.”

    That’s the best you got? Kidding aside, I know it’s not your best, but you have to admit that statement is a fair distance removed from “an overwhelming scientific consensus has determined humans are responsible for most of the global warming in the last xx years.” I appreciate the honesty, and it’s good to see some healthy scientific caveats emanating from the insistosphere.

  40. 90
    John Millett says:

    #32 Ray Ladbury,
    The 500 kg CO2 gorilla’s dad in the room is the 4000 kg H20 that also slows the rate of heat loss from the surface to space. (In and of themselves, the gorilla family would block about 1% of out-going infra-red radiation. Feedbacks, both positive and negative, are well known to climate science – much of the uncertainty revolves around the net effects of clouds which exhibit both forms). A slowing rate of heat loss means cooling more slowly than before, not warming. Surface temperature equilibrium is reached when the sum of the energy absorbed by the surface from the sun and the from atmosphere equals the energy it radiates to space. At equilibrium, changes to either the sun’s or the atmosphere’s radiation fluxes would determine whether the surface begins to warm or continues to cool. The changes need be only small to switch the temperature from equilibrium. We know from geology that the surface temperature periodically reaches equilibrium, switching between ice ages and inter-glacial warm periods. We know from the laws of physics and astronomy about the cyclical fluctuations on an increasing trend in the sun’s radiation. We know, from the same laws, about cyclical fluctuations in the sun’s magnetic field and, consequently, in the entry into the atmosphere of cosmic rays, a form of energy. We know from ice-core analysis about the cyclical variability in atmospheric concentration of CO2. We can find correlations between temperature on the one hand and both sun’s radiation and atmospheric concentration of CO2 on the other. We know that the latter correlation is time-shifted, temperature leading CO2 concentration. We ought, therefore, to agree that pre-human, or more precisely, pre-industrial climate change was caused by changes in solar activity; that these effects continue today; and that past changes in the atmospheric concentration of CO2 remain to be explained. We ought also to agree that fossil fuel burning industrialisation pumps increasing quantities of CO2 (plus water vapour and sensible heat – I wonder whether the models include these?) directly into the atmosphere. This is where questions and disagreements begin. The IPCC argues that these effects completely swamp solar ones, on two main grounds: first, the rate of warming in the latter half of the 20th century exceeds all previous experience; and second, otherwise their models don’t make sense. Well, the latter sounds a bit chicken and egg-ish to this layman. As to the former, the Central England temperature record contains a period of warming three times as much in two- thirds of the time. On the other side of the Atlantic, unpublicised revisions to the US temperature record reveal that six of the hottest ten years occurred in the first half of the 20th century. What I would like the climate models to tell me is when, in the absence of AGW, average global surface temperature would reach its zenith before beginning descent into the next ice age. I would also like a climate scientist to confirm that, in and of itself, CO2 would block no more than 0.04% of out-going infra-red radiation. A supplementary question: Would the absorbed energy raise the molecule’s temperature or increase its velocity or are these one and the same thing?

  41. 91
    Richard Wakefield says:

    Re 85:

    James, did you not read that abstract on sea level change?

    Science 26 October 2001:
    Vol. 294. no. 5543, pp. 840 – 842
    DOI: 10.1126/science.1063556
    Prev | Table of Contents | Next


    Sea Level Rise During Past 40 Years Determined from Satellite and in Situ Observations
    Cecile Cabanes, Anny Cazenave, Christian Le Provost

    The 3.2 ± 0.2 millimeter per year global mean sea level rise observed by the Topex/Poseidon satellite over 1993-98 is fully explained by thermal expansion of the oceans. For the period 1955-96, sea level rise derived from tide gauge data agrees well with thermal expansion computed at the same locations. However, we find that subsampling the thermosteric sea level at usual tide gauge positions leads to a thermosteric sea level rise twice as large as the “true” global mean. As a possible consequence, the 20th century sea level rise estimated from tide gauge records may have been overestimated.

    Twice 3.2 is 1.7 mm/y.

    As for your ref Nice try, but do you not see the downward last 10 years? Best to see it in a tighter perspective:


    [Response: You need to look at the same groups updates ie. Lombard A, Cazenave A, DoMinh K, Cabanes C, Nerem RS, GLOBAL AND PLANETARY CHANGE 48 (4): 303-312 OCT 2005. And please stay on topic. - gavin]

  42. 92
    Phil. Felton says:

    ” I would also like a climate scientist to confirm that, in and of itself, CO2 would block no more than 0.04% of out-going infra-red radiation. A supplementary question: Would the absorbed energy raise the molecule’s temperature or increase its velocity or are these one and the same thing?”

    I’m able to confirm that CO2 will absorb far more than 0.04% of the IR emitted from the surface, more like 10%.
    The absorbed energy will initially raise the rotational and vibrational temperature of the CO2 molecules which within less than a microsecond will raise the temperature of the surrounding molecules.

  43. 93
    Jim Eager says:

    Re John Millett @90: “We ought, therefore, to agree that pre-human, or more precisely, pre-industrial climate change was caused by changes in solar activity”

    Sorry, John, but changes in solar activity has never been the only and not always the dominant driver of climate change. Google “Milankovic cycles”, “Paleocene-Eocene Thermal Maximum”, “Permian-Triassic”, and “snowball Earth”, for example.

    John: “We ought also to agree that fossil fuel burning industrialisation pumps increasing quantities of CO2 (plus water vapour and sensible heat – I wonder whether the models include these?) directly into the atmosphere.”

    Water vapour from direct human activity does not need to be included–google “relative humidity.” Atmospheric water vapour content can not be permanently increased unless either atmospheric temperature or pressure is increased first, otherwise the addition simply rains or snows out in a matter of days. That said, increased water vapour as the atmosphere warms is included in the models. Sensible heat from human activity has been discussed and quantified here repeatedly, it is negligible.

    John: “The IPCC argues that these effects completely swamp solar ones, on two main grounds: first, the rate of warming in the latter half of the 20th century exceeds all previous experience; and second, otherwise their models don’t make sense. Well, the latter sounds a bit chicken and egg-ish to this layman.”

    It’s not only the models that do not make sense without including the effect of increasing CO2, John, observed reality doesn’t make sense without including it either.

    John: “On the other side of the Atlantic, unpublicised revisions to the US temperature record reveal that six of the hottest ten years occurred in the first half of the 20th century.”

    You’re falling prey to deliberate disinformation here, John.

    You have to go to the hundredth of a °C to break the tie between 1934 and 1998 for highest annual mean temperature anomaly (1.25 vs 1.23), and the following 23 ranked years, all above .50, are: 2006 (1.15), 1931 (1.00), 2005 (.99), 1999 (.94), 1953 (.90), 2001(.89), 1990 (.88), 2007 (.84), 1987 (.84), 1954 (.84), 1939 (.80), 1938 (.78), 1986 (.74), 1946 (.71), 1991 (.69), 2002 (.67), 1933 (.66), 2000 (.65), 2003 (.65), 1981 (.65), 1941 (.61), 2004 (.54), 1900 (.52).

    That’s only two years from the first half of the century in the top 10, not six, and 15 of the above 25 are since 1980.
    You might want to double check stuff like this that is easy enough to look up before you post next time.

  44. 94
    Jim Cross says:


    CO2 in the 1930′s was ~303 ppm.

    CO2 in the 90′s and 00′s is ~370 (currently ~380).

    Yet temperatures are only slightly higher now than 1930′s.


  45. 95
    Geoff Wexler says:

    1. An alternative approach. (Not really serious). One bet based on probability may not be decisive in determining the superior type of model. The trouble is that each model is consistent with a range of outcomes with different probabilities. Just for the sake of argument consider instead a couple of betting shops using different advisors to offer the public a range of bets with different odds. One shop would base its offers on the set of IPCC models and the other would use Keenlyside et al (perhaps supplemented by some more runs). The better modelling would be converted into a profit.

    2. Does the proposed bet suggest that the group are betting against the relevance of Schlesinger and Ramankutty ,1994. Nature,367,723 who looked at unforced oscillations of period 65-70 years period? They ended with the warning:

    “Accordingly, it is prudent not to expect continued year-after-year warming in the near future and, in so doing, diminish concern about global warming should global cooling instead manifest itself again.”

    Perhaps they really meant decade on decade. (Incidentally the German defeat in the 2nd world war has been partially attributed to the prolonged cold about 65 years ago). Its difficult for a non expert to judge the importance of individual papers.

    3. Coupling shocks. I suspect I have missed something. The green curve appears to have unphysical looking kinks at about 2000 and 2010; are these symptoms of coupling shocks? If so, what about the kink in the black curve at about 2010?

  46. 96
    Ron Taylor says:

    Re 84. In regard to Ed’s comment, I want to follow up with a related question.

    If there is a pause in surface warming because of cooler water being brought to the surface of the oceans, would this not lead to an increase in the energy imbalance, and thereby increase the rate of heat accumulation at the earth’s surface? The cooler ocean surface would radiate less IR back to space. Maybe the effect is negligible, or maybe there would be an offsetting negative feedback due to changes in clouds. I am asking.

  47. 97
    Hank Roberts says:

    > Jim Cross, temperatures

    Which ones, Jim?

    PS, I really appreciate your blog post on “How To Create a Major Software Outage”

  48. 98
    Rod B says:

    wmanny, “insistosphere” good! we need a screech name to counter all the labels laid on us skeptics. Makes the debate healthy.

  49. 99
    Lawrence Brown says:

    Re: Several comments on falsification.

    Just as current models can be verified by successfully reproducing the observed climate of the recent past century or so( the ones that include anthropogenic effects anyway), so can models be falsified by say, using orbital parameters such as the tilt of the Earth’s axis, and not being able to reproduce seasonal variations. Such a model would wrong.

    If a models have successfully shown the effects of sizable volcanic eruptions, as a number have, they’ve been verified, if a model could not, it’s been falsified. At least that’s my take on it.

    If this were not true, science counterparts of Elmer Gantry, could spout all kinds of nonsense, which may happen anyway, but it could not be shown to be wrong.

  50. 100
    Ray Ladbury says:

    John Millett, You make a lot of assertions with zero attribution. Some are true, some half true and some blatantly false.

    To correct the most blatant false notions:

    Each warming and cooling epoch in the paleoclimate has its own causes. In some cases these were based on solar variations, but in others volcanism, greenhouse warming and other factors were dominant.

    Then you say: “I would also like a climate scientist to confirm that, in and of itself, CO2 would block no more than 0.04% of out-going infra-red radiation.”

    Where the heck does that come from? Are we talking IR energy or IR photons?


    “A supplementary question: Would the absorbed energy raise the molecule’s temperature or increase its velocity or are these one and the same thing?”

    This sort of thing has been discussed repeatedly. First, how do you get a temperature for a single molecule? Second,



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