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CMIP5 simulations

Filed under: — gavin @ 11 August 2011

Climate modeling groups all across the world are racing to add their contributions to the CMIP5 archive of coupled model simulations. This coordinated project, proposed, conceived and specified by the climate modeling community itself, will be an important resource for analysts and for the IPCC AR5 report (due in 2013), and beyond.

There have been previous incarnations of the CMIP projects going back to the 1990s, but I think it’s safe to say that it was only with CMIP3 (in 2004/2005) that the project gained a real maturity. The CMIP3 archive was heavily used in the IPCC AR4 report – so much so that people often describe those models and simulations as the ‘IPCC models’. That is a reasonable shorthand, but is not really an accurate description (the models were not chosen by IPCC, designed by IPCC, or run by IPCC) even though I’ve used it on occasion. Part of the success of CMIP3 was the relatively open data access policy which allowed many scientists and hobbyists alike to access the data – many of whom were dealing with GCM output for the first time. Some 600 papers have been written using data from this archive. We discussed some of this success (and some of the problems) back in 2008.

Now that CMIP5 is gearing up for a similar exercise, it is worth looking into what has changed – it terms of both the model specifications, the requested simulations and the data serving to the wider community. Many of these issues are being discussed in a the current CLIVAR newsletter (Exchanges no. 56). (The references below are all to articles in this pdf).

There are three main novelties this time around that I think are noteworthy: the use of more interactive Earth System models, a focus on initiallised decadal predictions, and the inclusion of key paleo-climate simulations as part of the suite of runs.

The term Earth System Model is a little ambiguous with some people reserving that for models that include a carbon cycle, and others (including me) using it more generally to denote models with more interactive components than used in more standard (AR4-style) GCMs (i.e. atmospheric chemistry, aerosols, ice sheets, dynamic vegetation etc.). Regardless of terminology, the 20th Century historical simulations in CMIP5 will use a much more diverse set of model types than did the similar simulations in CMIP3 (where all models were standard coupled GCMs). That both expands the range of possible evaluations of the models, but also increases the complexity of that evaluation.

The ‘decadal prediction’ simulations are mostly being run with standard GCMs (see the article by Doblas-Reyes et al, p8). The different groups are trying multiple methods to initialise their ocean circulations and heat content at specific points in the past and are then seeing if they are able to better predict the actual course of events. This is very different from standard climate modelling where no attempt is made to synchronise modes of internal variability with the real world. The hope is that one can reduce the initial condition uncertainty for predictions in some useful way, though this has yet to be demonstrated. Early attempts to do this have had mixed results, and from what I’ve seen of the preliminary results in the CMIP5 runs, significant problems remain. This is one area to watch carefully though.

Personally, I am far more interested in the inclusion of the paleo component in CMIP5 (see Braconnot et al, p15). Paleo-climate simulations with the same models that are being used for the future projections allow for the possibility that we can have true ‘out-of-sample’ testing of the models over periods with significant climate changes. Much of the previous work in evaluating the IPCC models has been based on modern period skill metrics (the climatology, seasonality, interannual variability, the response to Pinatubo etc.), but while useful, this doesn’t encompass changes of the same magnitude as the changes predicted for the 21st Century. Including tests with simulations of the last glacial maximum, the Mid-Holocene or the Last Millennium greatly expands the range of model evaluation (see Schmidt (2010) for more discussion).

The CLIVAR newsletter has a number of other interesting articles, on CFMIP (p20), the scenarios begin used (RCPs) (p12), the ESG data delivery system (p40), satellite comparisons (p46, and p47) and the carbon-cycle simulations (p27). Indeed, the range of issues covered I think presages the depth and interest that the CMIP5 archive will eventually generate.

There will be a WCRP meeting in October in Denver that will be very focused on the CMIP5 results, and it is likely that much of context for the AR5 report will be reflected there.

113 Responses to “CMIP5 simulations”

  1. 51
    Edward Greisch says:

    44 prokaryotes: “a climate sensitivity of 8oC” OH S***!

    I hope the CMIP5 simulations can answer questions like whether an 8 degree C climate sensitivity is real. If it is correct, we are in a whole lot more trouble than I thought, which was a lot.

    Same for 43 Aaron Lewis: “we need to think about our current GHG concentration as 500 CO2- eq in 2011.” Because a doubling of equivalent CO2 would be 560 equivalent ppm, which is too soon.

    Another question for the models: Has the methane from Arctic wetlands taken it out of our hands yet? Is there still any action strong enough to turn the situation around?

    Dream list for the model: Let it be an engine for a game that gamer type regular people can play in which they can act out the 2050s. Design a popular Sim-Earth game around CMIP5 and sell a lot of games at low prices. Make it run on many platforms and the web. But make it all-too-real. The gamer dies of starvation. Maybe this is how we communicate it to the world.

  2. 52
    prokaryotes says:

    Edward Greisch:”Let it be an engine for a game that gamer type regular people can play in which they can act out the 2050s. Design a popular Sim-Earth game around CMIP5 and sell a lot of games at low prices. Make it run on many platforms and the web. But make it all-too-real. The gamer dies of starvation. Maybe this is how we communicate it to the world.”

    NASA Launches New MMORPG Moonbase Alpha

    But since it has become very quiet about this project… sad.

  3. 53
    wili says:

    A humble request:

    Can we have a main post examining the validity or lack thereof of the Wasdell paper that prokaryotes has brought to our attention?

    If it is garbage, it should be pretty easy for the experts here to shoot down and point out where the holes are. If it is spot on, we need to rethink a number of assumptions, at least.

    [Response: I gave it a quick skim. He is very confused and adds in and removes feedbacks in a rather willy-nilly manner. His CS value is based solely on the the fact that the last ice age was ~5 deg C colder and had 180 ppmv CO2. This is no good for calculating the Charney Sensitivity (because you are neglecting all other forcing terms), and it is a poor estimate of the Earth System Sensitivity because of the difficult-to-deal-with seasonality of the orbital forcing for creating the ice sheets in the first place. I was trying to remember where the name Wasdell came up before, and it was with a terrible piece in New Scientist accusing IPCC of neglecting water vapour feedback etc. He was wrong then, and he is wrong now. – gavin]

  4. 54
    prokaryotes says:

    Climate Sensitivity with David Wasdell

    Climate Sensitivity is made up of two fundamental parts. The first is the effect of doubling the concentration of atmospheric carbon dioxide on its own, holding all other system parameters constant. The second is the amplification of the primary change by a range of other system variables, namely the dynamic feedback system.
    The effect of doubling CO2 concentration on its own is extremely accurately known from observation, theoretical calculation and laboratory testing.
    It stands at 1.2oC and is represented by the black line on the semi-log scale below. The forcing generated by such an intervention is also accurately known to be 4.0 wm-2.
    The relationship between the two figures is governed by the Stefan-Boltzmann law concerning the energy radiated to the cold spatial sink by a “black body” at a given temperature. The ‘black body’ value is adjusted to take account of the emissivity of the planet. The change in radiation from the earth generated by a change of 1oC in surface temperature is 3.3wm-2.

    In climate models, the value of the amplification factor depends on which feedback mechanisms are taken into account, and on the competence of the modelling of the various feedback mechanisms and their complex interactions.

    Temperature-Forcing ratio. This definition answers the question about the equilibrium temperature change required to balance the effect of any given CO2 forcing. It is presented in degrees per watt per square metre, oCw-1m-2. Since a doubling of atmospheric concentration of carbon dioxide delivers a forcing of 4wm-2, the temperature-forcing ratio is one quarter of the climate sensitivity.

    Concentration-temperature ratio. This final definition relates the number of parts per million (by volume) of the atmospheric concentration of CO2 required to generate a shift of one degree in equilibrium temperature. Measured in ppmoC-1, it is specific to a given level of concentration and changes in step with the logarithmic decay in efficiency of CO2 to act as a greenhouse gas as its concentration increases. For instance if the concentration-temperature ratio is 20 ppmoC-1 when the concentration is 280 ppm, then it will increase to 40 ppmoC-1 when the concentration is 560 ppm, and 80 ppmoC-1 for a concentration of 1120 ppm.
    With this set of definitions in mind we can now proceed to explore the four main approaches to determining the increase in equilibrium temperature consequent upon any given increase in the atmospheric concentration of carbon dioxide.
    This paper has therefore adopted a graphical presentation using a semi- logarithmic scale in which the curves of normal log functions display as straight lines. The device enables clarity of comparison between a variety of amplification factors applied to the logarithmic relationship between carbon-dioxide concentration and the compensatory change in equilibrium temperature as enhanced by correlative feedback dynamics.
    One completely unanticipated outcome of using the semi-log display is the almost perfect symmetry between the 180 ppm and the 440 ppm values with respect to the pre-industrial benchmark. Implications of this symmetry are drawn out later in the paper, for now we simply note that the change in CO2 concentration from 180 ppm to 280 ppm may be expected to have the same effect as the increase in CO2 concentration from 280 ppm to 440 ppm, namely a shift of 5oC in the average surface temperature of the planet rather than the 2oC currently predicted as the equilibrium response to a concentration of 440 ppm.
    The amplification factor (AF) differentiates between the role of the change in concentration of atmospheric CO2, and that of the feedback system. It is defined as the ratio by which the feedback system multiplies the contribution of the forcing from any given change in atmospheric concentration of CO2. Like climate sensitivity, its value is also constrained by the condition of dynamic thermal equilibrium. The value of climate sensitivity is obtained by multiplying the effect of doubling CO2 concentration (1.2oC) by the amplification factor representing the contribution of the interdependent set of feedbacks in the earth system dynamic. The relationship is represented by the equation:
    S = 1.2 AF oC

    I suggest RC puts up a blog post, dedicated to the Wasdell paper…

  5. 55
    CM says:

    > I suggest RC puts up a blog post, dedicated to the Wasdell paper…

    I suggest not.
    But this existing post might help clarify a few things:

  6. 56
    Hank Roberts says:

    Gavin, thanks for the inline reply above.

    Proc, belatedly looking the guy up“David+Wasdell”+climate
    Wasdell is a religious/psychology writer, blog-flogging a new book. I think you’ve been following a red herring on this one. If you must continue, would you persist at your own blog? Way off topic for here, now that Gavin’s pointed out the guy’s previous mistakes.

  7. 57
    prokaryotes says:

    CM “I suggest not.”

    From the 2008 article: “…the conclusion that the Earth System sensitivity is greater than the Charney sensitivity is probably robust. And that is a concern for any policy based on a stabilization scenario significantly above where we are now.”

    The paper from Wasdell touches a lot new ground and basically brings up an entire new approach to quantify climate change, anthropocene climate change. Then does the article from 2008 leaves room for a lot of discussion, for example it does not even mention equilibrium. To reject a broader discussion of the Wasdell paper is a bit odd i think, unless you present a precise argument why that might not serve good. Especailly in light for policy implications.

    [Response: A good discussion of Earth System Sensitivity is found in Lunt et al (2010) (I’m a co-author) and I don’t think people disagree that the ESS is likely to be larger than the CS. That is not the issue. Nor is whether this is interesting or useful to calculate. My disagreement with what Wadsell has argued is all in how he has constructed his argument, not whether it is worth talking about. – gavin]

  8. 58
    prokaryotes says:

    Gavins response to wili: “in New Scientist accusing IPCC of neglecting water vapour feedback etc. He was wrong then, and he is wrong now.”

    I cannot read the entire article in the NS, but i wonder why a few years later then other climate scientist warn of the wv feedback… On the bottom line i would not reject a paper because he was proven wrong in the past. And i cannot find any ill advised motives here.

    Water Vapor Feedback Loop Will Cause Accelerated Global Warming, Professor Warns

    Gavin “This is no good for calculating the Charney Sensitivity (because you are neglecting all other forcing terms),”

    I don’t think so, because he uses a amplification factor and a logarythmic scale, also he notes briefly that his CS estimate is also underestimating the feedback cycle, because of other GHG.

  9. 59
    M says:

    1) From your sciencedaily link: ““Everything shows that the climate models are probably getting the water vapor feedback right,”

    That means that Dessler et al. were _confirming_ that models were already doing the right thing.

    2) “for now we simply note that the change in CO2 concentration from 180 ppm to 280 ppm may be expected to have the same effect as the increase in CO2 concentration from 280 ppm to 440 ppm”

    This assumes that there were no forcings on the Earth system other than CO2 in the historical era. We know, however, that that is wrong: changes in orbital dynamics led to ice sheet retreat, which, by itself, contributed close to half of the total temperature change. Because we don’t have those orbital changes or those ice sheets today, we wouldn’t expect as large a response.

    [Response: All other things being equal, the forcing from 180 to 280 ppm is 5.35*ln(280/180) = 2.4 W/m2, and from 280 to 440, it is 5.35*ln(440/280) = 2.4 W/m2 as well. So to that extent the statement is correct. What is wrong is associating a temperature change of 5 deg C to the former on the basis of the ice age/interglacial difference. This assumes that everything that changed between those two periods was because of the CO2 – it wasn’t. – gavin]

  10. 60
    Martin Vermeer says:

    Implications of this symmetry are drawn out later in the paper, for now we simply note that the change in CO2 concentration from 180 ppm to 280 ppm may be expected to have the same effect as the increase in CO2 concentration from 280 ppm to 440 ppm, namely a shift of 5oC in the average surface temperature of the planet rather than the 2oC currently predicted as the equilibrium response to a concentration of 440 ppm.

    …and that’s where Wasdell already goes off the rails. A large chunk of the 5oC temperature shift from glacial to interglacial was due to albedo loss — hey, huge ice sheets at low-ish latitudes were melting away — which will not be repeated in the same way from 280 to 440 ppm. And this is anyway a longer time scale thing.

  11. 61
    wili says:

    Thanks for the responses.

    Martin’s comment points up to me that whenever you compare two specific warming periods you end up getting into the specifics of what helped drive that particular warming. If the vast albedo shift of a heavily glaciated Northern Hemisphere turning into mostly open land and water is not a factor we have to worry about so much this time, what other particular events could potentially come into play in the next few decades?

    I had noticed that Wasdell had published something earlier that you disagreed with. I tried not to assume that one perhaps ill-thought-through article condemned all his future articles to be similarly ill-conceived.

    In light of your response above to prokaryote at #57:

    “A good discussion of Earth System Sensitivity is found in Lunt et al (2010) (I’m a co-author) and I don’t think people disagree that the ESS is likely to be larger than the CS. That is not the issue. Nor is whether this is interesting or useful to calculate. My disagreement with what Wadsell has argued is all in how he has constructed his argument, not whether it is worth talking about.”

    let me amend my humble request–could we have a main post that looks at ways one might come up with a reasonable approximation of how much larger ESS is likely to be than the CS?

    Thanks again.
    –wili/John Harkness

    (reCaptcha: icepatie cordata,)

  12. 62
    Hank Roberts says:

    > … disagreement … in how he has constructed his argument

    He’s no doubt a very nice man.
    But so are many people far out in various political directions.
    They all need help getting the science right, including him.
    You can see that just from the titles of his work.

    (space in URL added to get past the overeager spam filter)

  13. 63
    prokaryotes says:

    Martin Vermeer:”A large chunk of the 5oC temperature shift from glacial to interglacial was due to albedo loss…”

    I think to look at the periodically albedo loss of the earth is a good indicator to assess/project the fast advancing artificial albedo loss today, which is projected to advance in parts quiet rapidly (year to decade timescales). Still it is not clear to me why his approach is not further considered because of the historical temperature mark of 5C he uses. I find that makes a lot of sense to use the natural cycle as a basis.

    Wasdell:”“If the Charney sensitivity, supported by our modern computer models, projects that a doubling of the concentration of atmospheric carbon-dioxide leads to a temperature rise of 3oC at equilibrium, then why, in the empirically measured behaviour of the planetary system, does an increase of only 56% in CO2 concentration (from 180 ppm to 280 ppm) lead to a 5oC change in temperature?”
    If we take into account the non-linear relationship between the variables as expressed in the semi-log (base 2) presentation, the 56% increase in absolute value of the CO2 concentration across this particular range, equates to only 63.4% of the effect of doubling, i.e. a forcing of 2.54 wm-2. Applying the Charney Sensitivity to this proportion yields an increase of only 2oC for the change from coldest point of the ice-age to the pre-industrial benchmark. Historical data tells us that the shift should be 5oC. It just does not compute. The inescapable conclusion is that the computer modelling ensemble, together with the Charney sensitivity and supported by Hansen’s “empirical sensitivity” are all omitting something fundamental.
    They are grossly under-representing the contribution of the complex feedback system to the amplification of the effects of change in CO2 concentration.”

    And reading now..

    Earth system sensitivity inferred from Pliocene modelling and data

  14. 64
    Hank Roberts says:

    Oh, by the way, Wasdell cites Engelbeem at RC here:

    (space added to get around the spam filter)

    The pointer is meant to take readers to:

    Eric replied inline to that, pointing out where it’s wrong — but I doubt many readers get far enough to read that; Wasdell clearly did not bother to mention the response.

    I suspect Tamino would have a bit to say about his curve-fitting

  15. 65
    prokaryotes says:

    Hank Roberts if you look at other data with David Wasdell make sure to watch his latest interview too (at my block).

    What i start to understand now is that the issues surrounding climate sensitivity are nothing new and acknowledged by leading climate scientist. And in this regards it would be nice to see a blog dedicated to the latest science.

  16. 66
    Dr Nick Bone says:

    Wasdell’s paper seems pretty simplistic for the reasons Gavin mentions… you can’t assume that all the temperature difference between LGM and Holocene was due just to the CO2 difference.

    Even under the Earth System Sensitivity approach, with albedo changes treated as a slow feedback to greenhouse gas changes, CO2 is not the only GHG to consider: methane and NO2 also increased from LGM to Holocene. This is why Hansen et al got an ESS of 6°C for doubled CO2 rather than 7.8°C.

    But even then it’s not clear that Hansen et al have treated the orbital variations properly. Consider two thought experiments:

    1. Back during the LGM there is a huge series of volcanic eruptions, which increase the CO2 level, but of course leave the orbital forcings unchanged. Allow a couple of thousand years for albedo feedbacks and other slow feedbacks to complete. At the new equilibriun, CO2 level is now doubled at 360ppm, but no other changes in GHGs. What is the Earth’s new temperature?

    2. Opposite thought experiment. Orbital variations from LGM to Holocene are as for real history, but now the carbon cycle feedbacks are switched off. CO2 remains at 180ppm and other GHGs remain at LGM levels. Albedo feedbacks on the orbital forcings still happen. What is the Earth’s new temperature?

    If ESS is 6 degrees then the answer to question 1 is “Holocene maximum or a bit warmer” ie the CO2 change without orbital change has ended the ice age prematurely. Whereas the answer to question 2 is “Not very different from LGM” ie the orbital changes without CO2 changes have not had much effect at all, even allowing for albedo feedbacks. Those might be the right answers, but I don’t think we know that, and it seems rather an extreme attrribution of the changes between LGM and Holocene.

    So 6 degrees is probably close to an upper bound on ESS rather than a lower bound. I had a look at the other literature on ESS based on Pliocene temperatures and CO2 including Lunt et al, Pagani et al and Tripati et al. Most of those produce an ESS in the range of 4-6 degrees; certainly higher than Charney, but not 2.5 times higher.

  17. 67
    wili says:

    “So 6 degrees is probably close to an upper bound on ESS rather than a lower bound.”

    Not sure I follow you there. It seems to me that there are too many unknowns (and doubtless even more unknown unknowns) to be able to put a firm upper bound on ESS at this point, especially as it relates to our current situation where we are spewing CO2 into the atmosphere at a rate a couple of orders of magnitude faster than has ever happened in the paleo-record.

  18. 68
    Hank Roberts says:

    This is the blog you’ve been wishing for.

    They’re not doing high drama. Wasdell (and others *cough* Romm *cough*) believe high drama is necessary.

    Public reaction appears to be proving them right (dammit).
    But drama often includes oversimplification, and sometimes flat errors.
    You want to blog Wasdell? Point out that he’s got the right idea but made some mistakes in details as pointed out above — rather than echoing errors.

    Opportunity: doing the suggested reading; see what’s being done.
    Schmidt, G.A, 2010: Enhancing the relevance of palaeoclimate model/data comparisons for assessments of future climate change.

    —-excerpt from the opening of the topic—–

    …. Some 600 papers …. We discussed some … back in 2008.
    Now that CMIP5 is gearing up for a similar exercise, it is worth looking into what has changed – it terms of both the model specifications, the requested simulations and the data serving to the wider community. Many of these issues are being discussed … CLIVAR newsletter (Exchanges no. 56).

    Got that? (right click and “save as”)

  19. 69
    CM says:

    Re: Earth System Sensitivity, some reading: the Lunt et al. paper Gavin mentioned above is freely available here:

    And the discussion in the NAS Climate Stabilization Targets report looks helpful:

  20. 70
    Dr Nick Bone says:

    Re 67: “Not sure I follow you there. It seems to me that there are too many unknowns (and doubtless even more unknown unknowns) to be able to put a firm upper bound on ESS at this point”

    The logic is that if ESS is MORE than 6 degrees, then the temperature difference between LGM and Holocene would be bigger than what we observe/ reconstruct. (Even if the orbital variations themselves have minimal/no effect – see my thought experiment 2.)

    You can push the bound a bit by assuming a slightly higher temperature difference between LGM and Holocene (say 6 degrees rather than 5 degrees) and a slightly lower range of CO2 / other GHG variation (say 185ppm to
    275ppm CO2 rather than 180ppm to 280ppm). But that still doesn’t take ESS up to 8 degrees.

    Incidentally, I think Wasdell might me right but for the wrong reason, because the ESS is not the whole story. We need to look at carbon cycle feedbacks as well (i.e. the fact that Nature will respond to higher temperature by spitting out its own CO2 and methane into the atmosphere, adding to the CO2 we’ve already dumped their ourselves). Once you add those feedbacks in, we probably are up to about 8 degrees rise in response to us doubling CO2.

    See some of my previous postings here:

  21. 71
    prokaryotes says:

    Soil respiration & Denitrification Feedbacks and modeling
    What i did not read anywhere yet is how we quantify feedbacks from soil respiration(Co2) and denitrification(No2). When i read about the bio-geochemical feedback this might be covered there but so far i did not read any specific assessments.

    How does the modeling of these feedbacks work? Also under special circumstances there are other phenomena

    Soil carbon and climate change: from the Jenkinson effect to the compost-bomb instability
    More recently there has been a suggestion that the release of heat associated with soil decomposition, which is neglected in the vast majority of large-scale models, may be critically important under certain circumstances. Models with and without the extra self-heating from microbial respiration have been shown to yield significantly different results. The present paper presents a mathematical analysis of a tipping point or runaway feedback that can arise when the heat from microbial respiration is generated more rapidly than it can escape from the soil to the atmosphere.

    New study focuses on nitrogen in waterways as cause of nitrous oxide in the atmosphere
    The new study reports that streams and river networks are the source of at least 10 percent of human-caused nitrous oxide emission to the atmosphere worldwide, which is three times the amount estimated by an earlier report from the Intergovernmental Panel on Climate Change (IPCC).

    Denitrification takes place under special conditions in both terrestrial and marine ecosystems. In general, it occurs where oxygen, a more energetically favourable electron acceptor, is depleted, and bacteria respire nitrate as a substitute terminal electron acceptor.

    Ocean’s Harmful Low-Oxygen Zones Growing, Are Sensitive to Small Changes in Climate’s-carbon-dioxide-uptake-and-accelerates-hypoxia-states/

  22. 72

    Referring people to a new poster “The Software Architecture of Global Climate Models Key to Diagrams” from Kaitlin Alexander, Steve Easterbrook

  23. 73
    Hank Roberts says:

    > Dr. Nick Bone … previous postings
    Good pointer, thank you for the reminder.

    Carbon cycle feedbacks were in models at least as early as CMIP3, right? I know the marine biologists have been worrying about plankton changes for a long while, though I rarely see those discussed by modelers.

    Just poking around, I found this paper, originally out in 2008 for AR4, revised in 2011:

    Atmos. Chem. Phys., 11, 1417–1456, 2011

    Emulating coupled atmosphere-ocean and carbon cycle models with
    a simpler model, MAGICC6 – Part 1: Model description and

    “… This study presents the most comprehensive AOGCM and carbon cycle model emulation exercise to date. We use an updated version of the MAGICC model, which was originally developed by Wigley and Raper (1987, 1992) and which has been updated continuously since then (see e.g. Raper et al., 1996; Wigley and Raper, 2001; Wigley et al., 2009).

    Several amendments to MAGICC have been spurred by new results presented in the IPCC AR4 as well as by the increased availability of comprehensive AOGCM and carbon cycle model datasets. For example, land/ocean temperature evolutions for both hemispheres were calculated for each AOGCM allowing for a more in-depth analysis of optimal heat exchange parameterizations in MAGICC.

    Emulations with a simple model like MAGICC6 can by no means replace research into more sophisticated carbon cycle and general circulation models. Rather, what MAGICC6 offers primarily is a method to extend the knowledge created with AOGCMs and carbon cycle model runs in order to provide estimates of their joint responses and to extrapolate their key characteristics to a range of other scenarios….”

    [extra paragraph breaks added for online readability –hr]

  24. 74
    Didactylos says:

    “A line count of source code is a good proxy for complexity.” No. No, it’s not. It’s just one of the few measures we have, and we have to make do.

    It fails to distinguish between needed complexity and byzantine snarl-ups. Between the complexity of what the code does, and the code itself.

  25. 75
    Pete Dunkelberg says:

    Thank Heaven for Joe Romm and Climate Progress! Hank (# 68) we have a great problem. The problem at first looks like fossil fuels and increasing CO2, but why aren’t we solving this problem? Because of fossil fueled politics. Not because of the cost of renewable energy. Fossil fuel appears economical because significant costs of its use are not attributed to it. Solar energy for example could be ubiquitous. It could be on most rooftops and car tops. From the rooftops it could fuel cars and send power to the smart grid we could have.

    Who but Joe Romm at Climate Progress puts it all together – science, political lunacy and alternative energy – every single day and does a very good job of putting two and two together and getting four time after time despite the complexity of all the intertwined problems he deals with? And which commenters at which blog (*cough*) can’t decide within a factor of two what their favorite number is? :)

    Why can’t we (humans overall and especially the US) respond rationally to the great problems facing us? The whole business of deny, delay and make personal attacks on scientists is well crystallized by Juan Cole.

    And so our national debate is stunted and distorted. Instead of arguing over the best ways of dealing with our most pressing problems, we are reduced to disputing about whether a problem even exists. The latter is a rhetorical device of wealthy special interests designed to derail the ordinary workings of democracy.

    Instead of working on solutions to clear problems, public discourse has been forcibly dumbed down to the level of debating whether the problems even exist. So, Hank, the great need is to get the message out, and the message is “For crying out loud Virginia we really do have a serious problem.” Anything humanly beneficial requires a two thirds majority in 21st century democracy, so the message must get out to far more people than those who currently get it.

    Real Climate makes a valuable contribution to public knowledge of science. It is benefit to its readers, to all the other science blogs, thence to the world wide online community, thence to all the teaming human billions. Ditto for Climate Progress, and the latter addresses human as well as scientific matters. Climate Progress integrates things that people can actually do something about. We can’t do anything about climate sensitivity. It simply is what it is. And, Hank, …

    The exact value of sensitivity is not what matters in human terms. This is because corporate powers are determined to keep on burning carbon until they cook the last dollar out of us, no matter how much carbon it takes. What might stop them? Climate disruption might make business as usual impossible before we are totally cooked. Expect casualties. Lots of casualties. Or, humankind might rise up and make the obvious changes. What will motivate more people to constructive action sooner? Discussion of the exact value of sensitivity, or pounding away at fossil fueled politics day after day?

    Please, no more uncalled for remarks about Wasdell. He’s a religious spokesperson. You can’t expect him to use differential equations. He is concerned about human suffering and looming danger, as one would hope all religious spokespersons would be. Alas, too many have converted to the Holy Rightwing Church where greed is a sacrament not a sin. As a religious spokesperson he can reach people who tune science out. His audience is not going to take up atmospheric physics, but they need to understand that suffering will come if we persist in burning carbon as usual. There is a great human need to get beyond the numbed debate about whether there even is a problem. Let a hundred Wasdells bloom! If you want to be constructive, write to him privately about how to better express some tech details.

    So, Hank the crucial need is to get the message out that there really is a problem, and that it has aspects (politics, not sensitivity) that we can do something about if we will. Focus on that, and

    Thank Heaven for Climate Progress!

  26. 76
    prokaryotes says:

    Pete Dunkelberg, no it is absolutely irrelevant if Wasdell also used to be what you call a religious spokesperson. There are many scientist who also can be considered religious spokesperson. So i really don’t understand your argument.

    I look at Wasdell’s message and data and what he has to say. He does a great job with messaging, he says things easy to understand and points to risks. At least to me it was not obvious that climate sensitivity is so far considered, to be underestimated, which is crucial for decision making. In this regards Wasdell helped to bring awareness to this topic. Because i believe i follow the development of climate science closely i wonder how many people beside me are still not aware that we deal with an assessment which is not realistically. This in light of the media which in the past painted a picture of overestimation.

    Besides arguments from gavin about flaws of Wasdell’s draft i cannot understand why his figures are so fast skipped. I don’t think he was considering all GHG with his numbers as i pointed out above.

    Because of what i learned during the discussion here at RC i will shift my focus to other people when it comes to the work of climate sensitivity, namely pagani, lunt, tripati, gavin’s work and hansen ofc. But also will read future Wasdell releases. On the bottom line i fear that even when i cannot understand why Wasdell is so fast disregarded, most decision maker cannot either. In this sense i ask again for a better analysis of his work. And because his motives are not ill advised either. Maybe debunking denial has become to much of a concern and better messaging of the science at hand and where it lacks must be improved.

    What is more? In his latest interview he calls the denial what it is “A crime against humanity”. We need this kind of messaging to bring better awareness to the topic. Scientist must foster a stronger message to buckle up the public, based on their findings. And that does mean also better messaging when it comes to underestimation of work which is used as the basis for policy making!

    There are already enough extremes which can be used as examples to warn the public. In this regards Bill McKibben is great in messaging.

    To contact Wasdell is not easy because he has no contact on his website and emails from the draft paper do not work. Finally i found his email, but why should i contact him, that should be done by people with better insight on the flaws of his work. He is asking for contribution to the paper.

    So at last i point again to the interview with Wasdell from July, where he talks about his friend Lovelock and calls the denial what it is…

  27. 77
    prokaryotes says:

    Correction: The 8 part interview with Wasdell from July can be found here

  28. 78

    “[extra paragraph breaks added for online readability –hr]”

    Blessings upon you and your house forever for that!

  29. 79
    Brian Dodge says:

    “Climate disruption might make business as usual impossible before we are totally cooked.”

    At which point anthropogenic GHG emissions move from being a forcing (independent of the state of the climate) to a feedback(responding to the state of the climate); in this case, a negative feedback – as the climate gets warmer and less conducive to civilized BAU, fossil fuel consumption will fall, and eventually natural processes will start removing CO2 faster than we can put it into the atmosphere. I call this the Dodge Iris effect, which will act to stabilize the climate – at some new unit root equilibrium, which may allow survival of the remaining humans.

  30. 80
    wili says:

    @# 70 “I think Wasdell might me right but for the wrong reason”

    I suspect the same.

  31. 81
    Martin Vermeer says:

    prokaryotes, it should be possible to criticize the “good guys” when they get it wrong. Wasdell is undoubtedly well-intentioned, but in science that’s just not good enough. In its own way this is just as damaging as the “scientific denialists” like Spencer talking sensitivity down. An embarrassment and a liability to competent climatology.

  32. 82
    prokaryotes says:

    Oh come on Martin, he is not a climate scientist and if you read the first page, he is trying everything to make this a community afford. To compare him with Spencer is not very nice.

    I suggest every scientist should handle such work in a more constructive way, to show the public a) that climatology really is that complicated and b) to use this situation to bring attention to the topic. Overall isn’t this why RC exists in the first place? Everything else is not constructive and rather seems a bit arrogant.

    Now people say he was reasonable, and right (even for the wrong reason?!). Nevertheless i see your point but then again, there was no real coverage of climate sensitivity and underestimation, since a few years! At least not in the media i follow, Why? Just use this draft as an opportunity, to roll out the “real” science about CS.

  33. 83

    In the case of Wasdell — we perhaps see mistaken calculations that point to a resulting state which is not yet proven – but is never-the-less both possible and plausible – namely, runaway tipping points of no return.

    In the case of denialists like Spencer, Lindzen, et. al – we have mistaken calculations describing conditions more widely declared to be impossible and implausible – namely, global cooling or warming without an industrial CO2 influence.

    [Response: Both cases are implausible. It doesn’t matter whether Wasdell is rightly concerned about the issue, or whether Spencer and Lindzen are not. Only the logic and actual support for the claims are important in deciding whether they have merit. – gavin]

  34. 84
    wili says:

    Brian Dodge @#79: I think it is important to consider possible human actions as feedbacks, but it is even more difficult in this case to know what to expect. The main feedback from hotter temps in much of the world that can afford them would be increased use of air conditioning, mostly run on coal-powered electricity. If recent history is any indication, even very low EROEI sources of very dirty ff like tar sands are going to be used up. An immediate and total collapse of all world civilization may have the effect you claim, but that does not seem to be in the cards, as far as I can see. Meanwhile, desperate people do more and more desperate things–cutting down forests to burn to stay warm; hunting down every last wild animal to stay fed…

    It looks quite plausible and quite likely at this point that we will extract and burn nearly every ounce of fossil fuel that is recoverable. Energy is power. And power does not yield easily to persuasion. Wars are fought over the kinds of resources that we are asking people to walk away from voluntarily. We must keep asking and trying to persuade, but we can’t be too surprised that powerful forces are actively working against us and will continue to be.

  35. 85
    Dr. Skip T. Teck says:

    How’s that whole “polar amplification” thing holding up for you these days? BWAHAHAHAHAHAHAHAHHAHAAHA

    Absolutely loving watching your world implode in slow motion!!!! And there’s not a damn thing you can do about it.

  36. 86

    #83 Gavin: – agreed that deciding merit must rule science… but can I ask you to reconsider the importance of plausibility and risk in selecting areas of study?

    In 2006 you posted a fine essay on runaway tipping points of no return, in which you concluded:

    “Much of the discussion about tipping points, like the discussion about ‘dangerous interference’ with climate often implicitly assumes that there is just ‘a’ point at which things tip and become ‘dangerous’. This can lead to two seemingly opposite, and erroneous, conclusions – that nothing will happen until we reach the ‘point’ and conversely, that once we’ve reached it, there will be nothing that can be done about it. i.e. it promotes both a cavalier and fatalistic outlook. However, it seems more appropriate to view the system as having multiple tipping points and thresholds that range in importance and scale from the smallest ecosystem to the size of the planet. As the system is forced into new configurations more and more of those points are likely to be passed, but some of those points are more globally serious than others. An appreciation of that subtlety may be useful when reading some of the worst coverage on the topic.”

    Of course, toss out meritless studies, but shouldn’t there be a type of scientific triage where studies of plausible, high risk scenarios receive the corrective attention they deserve?

  37. 87


    Also, watch that IPP.

  38. 88
    Hank Roberts says:

    Richard, Wasdell doesn’t have a study.
    He doesn’t know what’s already been studied.
    He doesn’t talk about what’s in CMIP5 to be studied.
    He claims stuff isn’t being done that is being done.
    Digression avoids discussing reality.

    Look at the CMIP5 article, please.


    That’s the topic here — the studies being done for the next IPCC.

    Those are the studies being done.

    They do cover the range of concern.

    Talk about what’s really happening, not about unreliable accusations.

  39. 89
    Edward Greisch says:

    Reply to Hank Roberts, CM, prokaryotes, wili and others: I just finished reading “Delusional Democracy” by joel S. Hirschhorn. This book has a great deal to say about the way climate science is being treated, but not directly. Namely, we live in a plutocracy, and we had better save democracy quick. Science requires democracy.

    I started reading “Global Warming and Political Intimidation” by Raymond S. Bradley today. Bradley was one of the authors on the Hockey Stick paper with Michael Mann. Same problem: The plutocracy is against excessive truth, as all non-democratic governments are. The problem is systemic to the decay of democracy. It is not Climate Science alone that is in trouble, although it may seem that way.

    Wasdell’s sensitivity may not be the real issue. Sensitivity is clearly an important issue, but as I read this whole page, it seems to me that Wasdell’s sensitivity could be a symbol for something deeper. That something deeper would be the Political Intimidation that we all know is going on. The high end of the climate sensitivity distribution does need to be checked out carefully.

    Dodge Iris effect: Roger that. If the iris is open, somebody survives.

    86 richard pauli: Yes, those high risk scenarios and tipping points deserve our attention.

  40. 90
    Hank Roberts says:
    Wish: some science topics people can join only after doing the reading?

  41. 91
    prokaryotes says:

    Edward Greisch i agree, something larger seems at work. The weather in my region i can only describe as super strange, but the denial keeps on. Then look at the news and imagine how climate change might act on the world.

    What if?
    What if we already face an evolving disastrous situation and governments decide to preparing with building arks. Of course not everybody has the chance to join, that’s why you keep the denial up.

    At this point it is either keep denial up and start praying or worldwide combined large scale affords to reduce emissions.

    Read the Wasdell paper again, he is underestimating (Yes, yes he comes to the right conclusion but is technically wrong) …

  42. 92
    dhogaza says:

    How’s that whole “polar amplification” thing holding up for you these days? BWAHAHAHAHAHAHAHAHHAHAAHA

    The joke is on the troll, of course …

  43. 93
    Edward Greisch says:

    CMIP5 archive: “poorly understood feedbacks” and “develop additional experiments that might build on and augment the experiments described here.”

    91 prokaryotes: “right conclusion but is technically wrong” Confusion is settled one way: additional experiments.

    How can a retired robotic weapons engineer come out of retirement and help with the experiments that will help CMIP5 nail down the sensitivity?

    Or rather the sensitivity function generating mathematics, since sensitivity depends on time, the condition of the planet, and other stuff.

  44. 94

    #92–Oh, yes, indeed it is.

    By the way, I got an anonymous email response to an RC comment, awhile back, that sounded quite a bit like this one.

    Gutsy, that anonymous thing–nothing like having the courage of your convictions, I always say.

  45. 95
    Truthseeker says:

    For those that think that climate models are worth the effort, try this;

    [Response: What’s the logic here? Because some physicists/models have been wrong because of incorrect assumptions, it is therefore not worth doing any calculations? Strange. – gavin]

  46. 96
    Didactylos says:

    Truthseeker: this is why is is vitally important to validate models. And you know what? Scientists do validate models! Isn’t that amazing?

    It’s like they know that models are only a simplified version of the world, and that they contain all the assumptions we hold!

  47. 97
    spyder says:

    Just to put a bit more stress on the modeling, here is another relatively compendium analysis of several long term research studies:

  48. 98

    How vill the simulations take Peak Oil, Peak Gas and Peak Coal into acount. From what I have heard from Uppsala, are many models using IEA most optimistic. There is not that much oil and coal. IEA is not an expert on these matters, it is political organisation working for OECD. When they say “Fields yet to be found” in there WEO 2010, they cant get the numbers to add up.

  49. 99
    Hank Roberts says:

    Anyone know where the discussion of Salby’s ozone paper is? All I have is the Science reference I gave above that mentions some think something omitted:

    “a group of researchers claims they can already see the ozone hole slowly recovering. Many others, however, say the paper, now in press in Geophysical Research Letters, leaves out critical information needed to clinch the case.”

  50. 100
    Hank Roberts says:

    This refers to CMIP3 models:


    Are there two types of La Nina?
    Key Points
    La Nina events in the central and eastern Pacific SST are highly correlated
    There is a strong asymmetric character between El Nino and La Nina events
    CMIP3 models simulate the two types of El Nino more independently than La Nina