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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. 1

    And let’s not forget that the media largely misreported the results of this study because the authors use a very strained definition of the term “next decade.”
    http://climateprogress.org/2008/05/02/nature-article-on-cooling-confuses-revkin-media-deniers-next-decade-may-see-rapid-warming/

    As I explain, the Nature study is consistent with the following statements:

    * The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
    * The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
    * The fast warming would likely begin early in the next decade — similar to the 2007 prediction by the Hadley Center in Science (see http://climateprogress.org/2007/08/15/climate-forecast-hot-and-then-very-hot/).
    * The mean North American temperature for the decade from 2005 to 2015 is projected to be slightly warmer than the actual average temperature of the decade from 1993 to 2003

  2. 2

    I just heard the Keenlyside cooling prediction used on the radio to argue that
    there is no such thing as a climate crisis (by a guy from the office of Sen.
    James Inhofe, he of the hoax comment). Thanks for making this a betting matter,
    RC. It gives the question a higher profile. Scientific American says that ice
    sheets are sliding faster toward the sea. I’d say that’s a crisis .

  3. 3
    skids says:

    So the Chaiten eruption isn’t going to get big enough to call off the bet?

    [Response: Doesn't look like it. Not enough SO2. - gavin]

    [Response: And as I pointed out in response to an earlier similar comment, extratropical eruptions like this rarely give rise to a significant global mean cooling. - mike]

  4. 4
    John Cook says:

    Re the Chaiten eruption, from what I’ve read, a volcano needs to emit at least 1 million tons of sulfur dioxide into the stratosphere to have an effect on global temperature. Chaiten has only emitted an estimated few thousand tons of sulfur dioxide:
    http://ap.google.com/article/ALeqM5h6XCGT4X37OvMVvC6CA6UaDMeriAD90GHEFO0

  5. 5
    Martin Pierard says:

    Very interesting thanks.
    Recent evidence suggests that CO2 has now reached the level of 387 parts per million – what is the total figure for CO2 equivalents – probably more significant?
    Are we yet at a tipping point?

  6. 6

    Thank you very much for these 2 articles. I used the first 4000 characters of the first one on alternet.org/environment already.

    All bachelors level degrees, including journalism and English, should require the engineering and science core curriculum. Journalists do the journalism thing to sell papers. The journalism thing is exactly the wrong thing to do when reporting science. 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. A wager is a good idea and I think it is working for those who come in contact with your story in some way.

  7. 7

    Last week I criticised your bet as I thought it trivialised the issues involved but I understand your rationale better now.

    This post is exactly why this site is so popular for lay-people: it provides a clear explanation of climate change science and informed debate on current topics. Your best posts, like this one, allow lay-people to “see inside the heads” of how climate scientists think. For any objective, critical thinker reading your work the explanations of the assumptions you are making and the sources of error you identify both explain the issues involved and build confidence to accept your conclusions.

    As you say, your “assessment could of course be wrong” but a critical thinker reading your work is looking for the evidence and reasons you present to support your argument.

    Well done and thanks.

  8. 8
    Alexander Harvey says:

    Dear group,

    It seems a pity that you have had to use this hammer to crack a nut; but it works!!!

    If only… If only they had let their paper speak for itself and had left out the big claim. The sadness is that if we bury this and I suspect you, others and simply the passage of time will. The interesting part (can and how oscillations be predicticted) will be buried alongside the headline result.

    To me it seems such a pity for them and all of us.

    Best Wishes

    Alex Harvey

  9. 9
    Ron Taylor says:

    Why not propose your bet to Inhofe? The guy is utterly shameless.

  10. 10
    Mark A. York says:

    RE:#6,

    I have a journalism degree technically, but I have three times as many science credits in environmental biology, physical science, and work as an endangered species biologist for the US Forest Service and others. It’s a good point though since most top reporters come from Ivy league schools where no such requirement exists. Not so at public universities. Since graduating a couple of years ago, (non-traditional) I’ve not landed so much as an interview for a reporting job. Editors are science averse like that guy in Ely, Nevada! It’s a real problem.

  11. 11
    Richard Ordway says:

    Evidence shows that CO2 is going up at over 3% per year…Faster than in the highest IPCC scenario. Interesting to see if it continues at this rate…and what is causing it…drought?

    Good thing for the bet that there is a lag time.

    [Response: Emissions are rising 3% a year, concentrations at just over 0.5% a year (~2ppm). - gavin]

  12. 12
    ccpo says:

    Two excellent posts regarding Keenlyside, et al. As others have said, the paper is already being used to excuse denialists’ delusions despite the fact that the authors, themselves, say clearly that their paper does not contradict AGW and should not be used to assert it does. Rapid Climate Change is a real and present danger that short-sighted denialists/industrialists pay scant attention to. The delays in action created by the lies, distortions and muzzling done by Exxon and the Bush administration have already put the world into a percarious position given that climate changes are happening all over at far faster rates than ever considered possible just a year ago. Too many of the citizens of the US and Britain still believe there is substantive scientific uncertainty about climate change – even as George Bush lives in a “green,” off-grid home and now says climate change is real.

    One change I’m sure the Keenlyside authors couldn’t have considered is the much-more-rapid-than-expected release of methane in the Arctic that was reported in the last week or so. (Can’t find link now, but the results will do: http://www.csmonitor.com/2008/0428/p01s04-wogi.html )

    Keep up the good fight with good science.

    Cheers

  13. 13
    wmanny says:

    “Thanks for making this a betting matter, RC. It gives the question a higher profile.” I agree, but I wonder why RC does, as the higher profile gives the lie to the notion that there is universal scientific consensus on AGW. Granted Keenlyside predicts only a temporary reprieve before AGW predominates again, I doubt that nuance will make to the coverage of a Warming vs. Not Warming bet. RC fears the media is making an issue of Keenlyside temperature flattening — I see the media in comfortable lockstep with AGW proponents regardless of an occasional Keenlyside blip on the screen. AGW sells more papers, so to speak, than its absence. I admire the courage of RC’s convictions, then, because it has nothing to gain if the bet is won and everything to lose if the bet is lost.

  14. 14

    #13, wmanny that is such an disingenious, inaccurate, and lazy post.

    There is broad scientific consensus on the reality of anthropogenic climate change but there still a huge amount of ongoing research into many of the details. Keenlyside and his colleagues deal with some of the details but expressly state they not doubt the broad consensus view on the reality of anthropogenic climate change.

    Your suggestion that the bet offered by RealClimate “gives the lie to the notion that there is universal scientific consensus on AGW” is just plain wrong.

    Your comments about RealClimate’s motives and your suggestion that they are driven by “convictions” rather than good science indicate you are too lazy to engage them in a debate based on science and evidence.

    If you want to do some background reading on the scientific consensus statements (you seem in real need of it), there is a good compilation of them (with links) at http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change .

  15. 15
    Cat Black says:

    Re #13 “media in comfortable lockstep with AGW proponents” might have less to do with comfort and more to do with honest reporting. After all, they spent 20 years “comfortably” reporting the debate about AGW, but that debate is finally over, so the media have simply moved with the news. Can’t expect anything less, nor anything more, than that from the media.

    I guess I’m of two minds about this whole affair. Sure, let’s not let the “debate” thing derail us again just because a couple guys with a model think there might be a flat spot in the warming trend, if you hold the chart up to the light just so and squint.

    On the other hand… who gives a poop anymore? Seriously, it’s getting to the point where anyone who stands up in a crowd and says “my dog knows more about climate than Jim Hansen” is not going to like the reaction he gets. People in the streets are reading the reports carefully now, and what they are finding there gives little comfort. Setting aside the price of oil and its immediate impact on food, there is still enough going on with climate change and related water and agriculture issues to cause a prudent soul to glance around for an exit.

    Well we’re 7 billion prudent folk all glancing around nervous, and I’m not the first to point this out. And going forward, anyone says all this is just smoke and mirrors to get grants to study tree rings is advised not be standing under a sturdy limb and holding a rope when he’s saying it. If you follow my meaning.

  16. 16
    John Gribbin says:

    I love that “monotonously”! Maybe monotonically? Or is this another example of the transAtlantic divide in language?

    John

    [Response: Thanks John, fixed that. Not transAtlantic, but we're not all born native speakers of the global language of science. -stefan]

    [Response: Actually, I almost changed that when were editing, but I thought monotonously was a little more apt.... - gavin]

  17. 17
    Matthew Brunker says:

    Latif’s group does not have much experience in modelling the MOC. But how could they (and the Nature reviewers) have overlooked so many obvious red flags? The fact that the hindcasts with their method perform worse than a standard IPCC scenario, the number of failed previous cooling predictions, the negative skill in the Gulf Stream and deep-water formation regions… should these not have cautioned them against going to the media to forecast a pause in global warming? Your bet does a good service, but I fear that it cannot undo the damage that they have already done in confusing the media public about global warming.

  18. 18
    Nylo says:

    Gavin, you responded at #11 that emissions are rising at 3% per year while concentrations only rise at 0.5% per year. That is somewhat logical because there was already some concentration before we started any emissions. However there is another phenomenon that I have been unable to understand, and I would like to know if there is any theory that explains it.

    Between the 80′s and the 90′s, man-made emissions of carbon from fosil fuels increased from about 5 billion tons per year to about 6.5 billion tons per year, which means a 30% increase in how much CO2 we put into the atmosphere yearly. However, the ratio at which CO2 concentration increases in the atmosphere slowed down between the 80′s and the 90′s, from 1.6 ppm/year to 1.5 ppm/year. Is there an explanation for that? Do you think it could be related to the rising temperatures and how it affects the Earth’s capability to sequester atmospheric CO2 by natural processes like the photosintesis of the plants? Or is there something else? And whatever the cause may be, is it predicted in the models?

    Thanks.

  19. 19
    Alex Thomas says:

    “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”

    Why does the HadCRU3 temperature data not show the cooling in the 1970s? Does the forecast of Keenlyside et al for this period, of a cooling, reflect the cooling in the 70s from other datasets?

  20. 20
    Ed says:

    Re: coupling shock

    Nice summary. I read the paper as saying that they are restoring to SST anomalies rather than the raw SSTs themselves – does this make a difference?

    [Response: Not to the coupling shock problem. -stefan]

  21. 21
    Gareth John Evans says:

    There is no need to bet when you stick to the science (and measured data and observations as much as possible). The green line “forecast” for the period 1995-2000 in the graph above is well below actual observations for the same period. This speaks for itself.

    Also, evidence of the affects of global warming from many parts of the world speaks for itself – melting ice, droughts, increasing water supply problems in big cities like Barcelona etc.

    What causes doubt and confusion is that the effects of global warming are not uniform around the globe and there are always weather fluctuations (that may even increase in scale and predictability) as global warming progresses. Global circulation patterns are very complex and the effects of any changes are so difficult to predict on a local, regional level. This is why we need a focus on regional and local studies, observations, and assessment that do not depend so heavily on models.

    Professor Molina, Nobel Prize (chemistry) issued a stark warning recently (April, 2008) by suggesting that, “…long before we run out of oil, we will run out of atmosphere”. Professor Santilli (nominationed for the Nobel Prize in chemistry and physics) has raised the issue of atmospheric oxygen depletion – particularly in some of our largest cities around the world. The Chinese, for example, have planted a forest twice the size of New York’s Central Park on a 1,750-acre site north of the Olympic village in Beijing, to raise oxygen levels. Nearly a dozen factories are also closing or relocating outside Beijing, and factories hundreds of kilometres away will suspend operations for the duration of the olympics.

    Our emissions to the atmosphere impact on natural processes, the environment, and health in very many ways – the ozone hole was the first big warning. It is so important that we learn, inform and educate on the basis of the best known science – illiminating guesswork (and certainly no bets)!

  22. 22
    Ed says:

    Re: RMS error and correlation skill

    The supplementary information to the paper has an interesting figure – Supp. Fig. 2c shows the difference in RMS (root mean square) error (as compared to the correlation maps shown in the main paper) between the hindcasts and non-initialised cases. There it demonstrates that the RMS error in the Atlantic is worse in the forecast cases compared to the non-initialised cases. There are a few regions where the forecast appears more skillful in this metric of skill, which could be viewed as more relevant when making forecasts.

  23. 23
    Mark says:

    You are always very polite and diplomatic. The guts of this story is really quite funny: a group of climate scientists manages to sell a weird model result, most likely an artifact due to an inadequate modeling technique, as a sensational forecast to Nature and the world media…

    I think the lesson of this story is that it is rather problematic that new climate science papers are now all over the media within hours of appearing in a journal, with political implications being discussed before the scientific community had time to properly assess and discuss the new study.

  24. 24
    Mauri Pelto says:

    Brilliant article review, I hope I can capture some of the magic in the paper I am reviewing today. I understand the gist of coupling shock, but can you provide an example of how it would play out, and what can be done to identify and quantify this result.

  25. 25
    pete best says:

    Re #22, yes the media has to learn that peer review is not the end of the scientific process but part of an ongoing process of validation and verification before it is allowed into the hallowed halls of scientific truths.

  26. 26
    Cobblyworlds says:

    Whilst bets are of no use in determining the underlying physical reality, they are very useful in sorting out people’s real level of confidence in their predictions. This can be a useful indicator how strongly we lay-people should factor them into out considerations.

    I do hope Keenlyside’s team post here, their take would be interesting. From a policy and adaptation point of view such efforts to make more accurate short-term predictions could be valuable, if time bears out their predictions.

    #5 Martin Pierard,
    I wouldn’t think of a single global tipping point as such, what’s important in this respect are the different climate subsystems. In that respect you may find this page interesting:
    http://www.pik-potsdam.de/infodesk/tipping-points

    #17 Nylo,
    Those CO2 increments seem all over the place to me, when viewed on a short term basis:
    http://www.esrl.noaa.gov/gmd/ccgg/trends/ scroll down to global average.
    1998 is interesting, but without looking at what’s happening regionally I wouldn’t read too much into most of the year-to year variance. What is apparent is that on a multi-year basis the ppm/year increase is going up, try something like a 5 year moving average to filter inter-annual difference for the full record.

    With regards CO2 emissions uptake, have you read David Archer’s post on this? http://www.realclimate.org/index.php/archives/2007/11/is-the-ocean-carbon-sink-sinking/

    #19 Gareth John Evans,
    Out of interest, the Arctic Oscillation/North Atlantic Oscillation (which are intrinsically linked) seem to have a key role in both the Arctic ice loss (outflushing through the Fram Strait) – Rigor/Wallace) and the Mediterranean drying e.g. Figen Mekik’s post at RC http://www.realclimate.org/index.php/archives/2007/10/sweatin-the-mediterranean-heat/

    Professor Molina, Nobel Prize (chemistry) issued a stark warning recently (April, 2008) by suggesting that, “…long before we run out of oil, we will run out of atmosphere”.

    Mmmmm, I’m far from convinced.

  27. 27
    Ray Ladbury says:

    wmanny #13–Let’s get one thing straight. The consensus of scientists on climate change is that humans, by releasing massive amounts of the greenhouse gas, CO2, into the atmosphere, are largely responsible for the current epoch of warming. Keenlyside et al. is part of that consensus, not a challenge to it.

    You say, “I see the media in comfortable lockstep with AGW proponents… ”

    Well, I’ve always found the truth to be more comfortable than any lie. Actually, the media lag far behind the scientists in terms of the level of consensus. If they really understood the science, then the occasional outbursts by denialists would generate no more notice than a fart in polite company–a little embarassment for the offender, but no overt comment.

  28. 28
    Phil. Felton says:

    Re #10

    ” It’s a good point though since most top reporters come from Ivy league schools where no such requirement exists.”

    That’s certainly not true of the one where I teach.

  29. 29
    CarbonSink51 says:

    It is true that old fears of a new ice age did not originate with climate scientists [edit - no nonsense please] and I confess to being someone who worried about such things at that time. But was I wrong? When estimates of a possible return of an ice age still vary between this week and 50,000 years why should I be confident that the guys with tenure and titles have a handle on it?

    In that large, mysterious (to me, anyway) context, listening to climate scientists boldly predict changes or non-changes in the range of tenths of degrees over a mere 10 or 20 years strikes me as more than just a tad beyond hubris and more like a standard deviation or two into the delusional range. One volcanic burp, one solar belch, a passing cosmic cloud or some butterfly flapping its wings in New Jersey and entire models can become just really bad computer games.

    I admire the creativity and genius in climate modeling and the insights it can provide but when you guys start thinking it’s real, maybe it’s time to back away from the keyboard for a bit.

    Without the ugly constraints of the overarching politicized death struggle, there is a beauty even in the uncertainties of this pursuit. To minimize or even fail to investigate uncertainties lest it give comfort to the denialist foe is no way to live.

  30. 30

    #29 – the phenomenon of greenhouse gases retaining heat at the surface of the earth operates on decadal scales, and the orbital variations (Milankovitch cycles) which cause the waxing and waning of the ice ages operate on millennial scales, and both are fundamental physical processes, and are not elucidated by computer models. Nothing is going to change those results, short of a complete refutation of fundamental physics – unlikely.

    The computer models deal with the actual energy and matter flows within, and in and out of the system, and do not account for random geological or cosmological events, such as volcanic eruptions or asteroid impacts, solar disturbances, etc. However, these computer models are also based in fundamental physics, and the random events can be modelled as well, if not predicted in advance.

  31. 31
    Richard Wakefield says:

    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]

  32. 32
    Ray Ladbury says:

    CarbonSink51, Spoken like a man who doesn’t understand the science. Look, the GCMs are complicated, and yes there are uncertainties, but the fundamental reality, the 800 pound gorilla in the room is the fact that CO2 traps outgoing infrared radiation. Since such radiation is the only way energy escapes the climate system, that has to heat things up. Since the only escape clause is some magical negative feedback that kicks in to keep climate from warming above its current level, and since there is no such mechanism known and further since climate has warmed above this level in the distant past, I’d say this is pretty darned unlikely. Those who look to such a mechanism are appealing to Disney’s first law–Wishing will make it so.

  33. 33
    veritas36 says:

    Sad to say, I keep hearing people — and these are bright people — say “I don’t believe in global warming.” I don’t know how to get away from paralyzing fear that must be the driver of this sort of comment — they don’t want to believe it.

    I’m writing a novel with a denier in it, and tried to come up with a carp about the GW science that hasn’t been used. Just my luck, I decide the denier announces that global cooling has begun! reality imitating art…

  34. 34
    Hank Roberts says:

    > 21, Gareth

    Molina was talking about climate change.

    Santilli? Look him up. Utterly off topic.

  35. 35
    Chad says:

    You don’t have permission to access /~stefan/Publications/Journals/rahmstorf_climdyn95.pdf on this server.

    [Response: I made a local version you shouldn't have a problem with (link above). - gavin]

  36. 36
    Richard Ordway says:

    [Response: Emissions are rising 3% a year, concentrations at just over 0.5% a year (~2ppm). - gavin]

    Hi Gavin,

    I clearly heard the exact phrase “over 3%” deliberately and clearly stated yesterday at a government-funded research institute in Boulder at a presentation by a visiting publishing scientist using the latest sources who is researching the latest CO2 trend anomalies.

    Of course, this is my own personal opinion, the researcher might have been exagerating (I doubt it..the researcher would have been crucified by other publishing experts present..not to mention their reputation) and my statement is not in any way connected to any single institution.

  37. 37
    Alien says:

    This is nice, that climate scientists have reached consensus. If you want to convice the general public to the “tipping point” that we actually as a society begin to do something about it. You must preserve your credibility, and resist the temptation to say, every time that there is a hot day or a hurricane “see-it is global warming”. Because surely then when there is a cold day or a calm season, you have taught the deniers.
    And when the arctic ice melts – faster than the models predict – who can say this is AGW?

    Alien (Only art, no science)

    [Response: If you care to look, we have been remarkably consistent on that point. - gavin]

  38. 38
    Steve Bloom says:

    Re #36: Possibly a reference to the increase in the rate?

  39. 39
    dhogaza says:

    And when the arctic ice melts – faster than the models predict – who can say this is AGW?

    Why do you think it’s melting? Global cooling?

  40. 40
    Ray Ladbury says:

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

  41. 41
    Alien says:

    RE#38 I think that we are in deep doo doo a’la AGW. I am just pointing out that if the speed of arctic ice melting is outside the parameters that are predicted by the model, then the model might be wrong.
    Alien

  42. 42
    Sean O says:

    As one that repeatedly asked that you rescind your bet in favor of a gentleman’s bet, I commend you for agreeing to a non-financial bet. I still believe that the wager is too high but it will be interesting if Keenlyside et. al. will respond with terms that are more fitting with science and its discussion – perhaps a year’s subscription to Nature magazine for the inner city high school of the winner’s choice.

    One question on your logic that I don’t quite understand (and perhaps I am misinterpreting the chart at the top of the article). You state in point 2 that since there are two false cooling forecasts that the model is suspect. While I grant you that the large gap in the late 90s is of huge concern, isn’t that same concern warranted with the large continuous gap from actual in the IPCC hindcast from 1965 to 1985?

  43. 43
    Richard Ordway says:

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

    No biggie, but Gavin I’m sure has my two IP addresses. One of them is rather blatent and has been so for the two years or so that I’ve been posting on this blog.

  44. 44
    Chris says:

    Re #42 Sean O,

    No there isn’t a concern about the IPCC model and the small deviations from the measured temperature evolution during the period around 1970-1985. The IPCC models make no claim to reproduce every variation in the temperature evolution in response to enhanced greenhouse forcing. That’s the whole point, of course. Everyone recognises that the Earth undergoes a warming response to enhanced greenhouse forcing. In general it’s recognised that prediction of the so far unpredictable phenomena (El Nino’s, La Nina’s, the fine details of ocean circulation oscillations, volcanos and any solar variation outwith the 11 year solar cycle) that provide short term modulation of any trend is likley to be unfruitful at present.

    However Keenleyside et al are claiming to be able to predict the trend incorporating these short term modulations. Therefore Keenleyside’s assertions concerning the short term should be subject to the degree of scrutiny commensurate with their particular claim. That doesn’t apply to the IPCC simulations since they make no such claim of being able to predict short term modulations of the long term trend. That’s obvious isn’t it?

  45. 45
    Joel Shore says:

    Re #18: Nylo says “Gavin, you responded at #11 that emissions are rising at 3% per year while concentrations only rise at 0.5% per year. That is somewhat logical because there was already some concentration before we started any emissions.” Actually, you are trying to compare two numbers that have completely different meanings…It is an apples-to-oranges comparison. The 3% per year is the amount by which the emissions are increasing…and (assuming that the fraction of this that stays in the atmosphere is constant) this would then be essentially proportional to the second derivative of the concentration of CO2 in the atmosphere with respect to time. However, the 0.5% per year is the rate at which the concentration of CO2 in the atmosphere is increasing…i.e., it is essentially the first derivative of the concentration of CO2 in the atmosphere with respect to time.

    Thus, whether this 0.5% value is less than, greater than, or equal to the 3% value is irrelevant. It is sort of like trying to figure out if my weight in pounds is less than my height in centimeters and attaching some deep meaning to it.

  46. 46
    Jared says:

    #1

    “As I explain, the Nature study is consistent with the following statements:

    * The “coming decade” (2010 to 2020) is poised to be the warmest on record, globally.
    * The coming decade is poised to see faster temperature rise than any decade since the authors’ calculations began in 1960.
    * The fast warming would likely begin early in the next decade — similar to the 2007 prediction by the Hadley Center in Science”

    If 2005-2015 turns out to be cooler than 1995-2005, do you think that would be cause to question the projected warming for 2010 to 2020? What about longer projections? I guess my main question is: what projections of warming can be accurately assessed for their true accuracy in the short term (next ten years or so)?

  47. 47
    Jared says:

    #44

    “Everyone recognises that the Earth undergoes a warming response to enhanced greenhouse forcing.”

    But what is debatable is the degree of that warming response, and what amount of forcing correlates into how much warming. And how much of the warming seen in the past century is conclusively due to GHG.

  48. 48
    Hank Roberts says:

    > debatable

    Wrong concept, for scientific work.
    Try for publishable. It’s harder, but it’s useful.

  49. 49
    gmb says:

    Re: 27

    “Actually, the media lag far behind the scientists in terms of the level of consensus.”

    No doubt. Generally, the public forms views by what it sees in the media and internet (not peer-reviewed journals, academia, scientific conferences, or the consensus from the major science academies) and what I see in the general media a pretty even mix, with many outlets covering contrarians exclusively (such as the WSJ op-ed columns to name one of many). The result is that the same handful of contrarian names get constantly recycled to the point where they have long reached virtual celebrity status. It’s a little disconcerting.

    RC is an outstanding site and I’m amazed at the patience the scientists express here, but for every site of this quality there seem to be several junkscience.coms.

  50. 50
    Peter Johns says:

    Why did GISSTEMP for March fall from 0.81 deg to 0.68 deg?
    http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt
    This makes the first 4 months of 2008 the coolest since 2000.
    PJ


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