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Sensitive But Unclassified

The US federal government goes to quite a lot of effort to (mostly successfully) keep sensitive but unclassified (SBU) information (like personal data) out of the hands of people who would abuse it. But when it comes to the latest climate models, quite a few are SBU as well.

The results from climate models that are being run for CMIP6 have been talked about for a few months as the papers describing them have made it in to the literature, and the first assessments of the multi-model ensemble have been done. For those of you not familiar with the CMIP process, it is a periodic exercise for any climate model groups who want to have their results compared with other models and observations in a consistent manner. CMIP6 is the 5th iteration of this exercise (we skipped CMIP4 for reasons that remain a little obscure) that has been going since the 1990s.

The main focus has been on the climate sensitivity of these models – not necessarily because it’s the most important diagnostic, but it is an easily calculated short-hand to encapsulate the total feedbacks that occur as you increase CO2.

The first public hint of something strange going on, was at the Barcelona CMIP6 meeting in March earlier this year where this graphic showing Equilibrium Climate Sensitivity (ECS) for the models was prepared:

This showed that quite a few of the models were possibly coming in with sensitivities above 5ºC (grey bars were self-reported, green bars were calculated coherently from the archive). At about the same time, developers at the Hadley Centre and IPSL, wrote about their preliminary results. This was news because the previous IPCC report (and most assessments) have found the likely range of climate sensitivity is roughly 2 to 4.5ºC. For contrast the range in CMIP5 models was 2.1 to 4.6ºC.

As more models have been put into the database (all of which is publically available), more consistent estimates are possible, for instance:

So what should people make of this? Here are some options:

  • These new higher numbers might be correct. As cloud micro-physical understanding has improved and models better match the real climate, they will converge on a higher ECS.
  • These new numbers are not correct. There are however many ways in which this might have manifest:
    • The high ECS models have all included something new and wrong.
    • They have all neglected a key process that should have been included with the package they did implement.
    • There has been some overfitting to imperfect observations.
    • The experimental set-up from which the ECS numbers are calculated is flawed.

There are arguments pro and con for each of these possibilities, and it is premature to decide which of them are relevant. It isn’t even clear that there is one answer that will explain all the high values – it might all be a coincidence – a catalogue of unfortunate choices that give this emergent pattern. We probably won’t find out for a while – though many people are now looking at this.

Why might the numbers be correct? All the preliminary analyses I’ve seen with respect to matches to present day climatologies and variability indicate that the skill scores of the new models (collectively, not just the high ECS ones) are improved over the previous versions. This is discussed in Gettelman et al. (2019) (CESM2), Sellar et al (2019) (UKESM1) etc. Indeed, this is a generic pattern in model development. However, up until now, there has not been any clear relationship between overall skill and climate sensitivity. Whether this will now change is (as yet) unclear.

Why might these numbers be wrong? Well, the independent constraints from the historical changes since the 19th C, or from paleo-climate or from emergent constraints in the CMIP5 models collectively suggest lower numbers (classically 2 to 4.5ºC) and new assessments of these constraints are likely to confirm it. For all these constraints to be wrong, a lot of things have to fall out just right (forcings at the LGM would have to be wrong by a factor of two, asymmetries between cooling and warming might need to be larger than we think, pattern effects need to be very important etc.). That seems unlikely.

But if these numbers are wrong, what is the explanation? Discussions with multiple groups indicates that there isn’t one new thing that all of these groups have included (and the other groups have not) or vice versa. Neither is there some dataset to which they have all tuned their models to that is flawed. The closest might be the CERES TOA radiation, or perhaps CloudSAT/CALIPSO data, but there is no indication there are any fundamental issues with them.

There is some indication that for the models with higher ECS that the changes in the abrupt4xCO2 runs are changing so much (more than 10ºC warming) that the models might be exceeding the bounds for which some aspects are valid. Note these are the runs from which the ECS is calculated. What do I mean by this? Take the HadGEM3 model. The Hardiman et al. (2019) paper reports on an artifact in the standard runs related to the rising of the tropopause that ends up putting (fixed) high stratospheric ozone in the troposphere causing an incorrect warming of the tropopause and a massive change of stratospheric water vapor – leading to a positive (and erroneous) amplification of the warming (by about 0.6ºC). Are there other assumptions in these runs that are no longer valid at 10ºC warming? Almost certainly. Is that the explanation? Perhaps not – it turns out that most (though not all) high ECS models also have high transient climate responses (TCR) which happen at much smaller global mean changes (< 3ºC).

What is clear is that (for the first time) the discord between the GCMs and the external constraints is going to cause a headache for the upcoming IPCC report. The deadline for papers to be submitted for consideration for the second order draft is in December 2019, and while there will be some papers on this topic submitted by then. I am not confident that the basic conundrums will be resolved. Thus the chapter on climate sensitivity is going to be contrasted strongly with the chapter on model projections. Model democracy (one model, one vote) is a obviously a terrible idea and if adopted in AR6, will be even more problematic. However, no other scheme has been demonstrated to work better.

Interesting times ahead.

References

  1. A. Gettelman, C. Hannay, J.T. Bacmeister, R.B. Neale, A.G. Pendergrass, G. Danabasoglu, J. Lamarque, J.T. Fasullo, D.A. Bailey, D.M. Lawrence, and M.J. Mills, "High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)", Geophysical Research Letters, vol. 46, pp. 8329-8337, 2019. http://dx.doi.org/10.1029/2019GL083978
  2. A.A. Sellar, C.G. Jones, J. Mulcahy, Y. Tang, A. Yool, A. Wiltshire, F.M. O'Connor, M. Stringer, R. Hill, J. Palmieri, S. Woodward, L. Mora, T. Kuhlbrodt, S. Rumbold, D.I. Kelley, R. Ellis, C.E. Johnson, J. Walton, N.L. Abraham, M.B. Andrews, T. Andrews, A.T. Archibald, S. Berthou, E. Burke, E. Blockley, K. Carslaw, M. Dalvi, J. Edwards, G.A. Folberth, N. Gedney, P.T. Griffiths, A.B. Harper, M.A. Hendry, A.J. Hewitt, B. Johnson, A. Jones, C.D. Jones, J. Keeble, S. Liddicoat, O. Morgenstern, R.J. Parker, V. Predoi, E. Robertson, A. Siahaan, R.S. Smith, R. Swaminathan, M.T. Woodhouse, G. Zeng, and M. Zerroukat, "UKESM1: Description and evaluation of the UK Earth System Model", Journal of Advances in Modeling Earth Systems, 2019. http://dx.doi.org/10.1029/2019MS001739
  3. S.C. Hardiman, M.B. Andrews, T. Andrews, A.C. Bushell, N.J. Dunstone, H. Dyson, G.S. Jones, J.R. Knight, E. Neininger, F.M. O'Connor, J.K. Ridley, M.A. Ringer, A.A. Scaife, C.A. Senior, and R.A. Wood, "The impact of prescribed ozone in climate projections run with HadGEM3‐GC3.1", Journal of Advances in Modeling Earth Systems, 2019. http://dx.doi.org/10.1029/2019MS001714

45 Responses to “Sensitive But Unclassified”

  1. 1
    Tim Osborn says:

    Alternative schemes to “one model, one vote” should ideally have a firm basis in the literature before being implemented for AR6 projections chapter(s). So the deadline of submission by 31 Dec 2019 is a constraint for that aspect as well as for better understanding the discord between GCMs and external constraints. The two things are related and aren’t the same. One is about why the problem exists (or if it exists), the other is about how to cope with the problem (assuming it exists, and your arguments suggest it does).

  2. 2
    Nemesis says:

    Why is it, that I can never get that “faster/higher/hotter” meme out of my head? I’m reminded of it when I read climate articles, when I watch TV (I don’t have any) and commercials, when I read the news, when I watch the sick car traffic all around me, when I watch the people out there, when I watch the overall ecological damage being done day in, day out, when I watch the stock market ect ect, that funny “faster/higher/hotter” meme permanently sticks in my head like a spell or something… Why is it? Doesn’t it pretty much look like it’s just systemic in the overall system?… Welcome to the Machine.

    ” Interesting times ahead.”

    Indeed, indeed.

  3. 3
    steven mosher says:

    nice overview. thx

  4. 4
    Killian says:

    I’ll say it again: There is no corollary to the present. Never before, save Chicxulub, has the entire planet been degraded as a change happened. The various systems that make up the planetary system, unless my logic is unsound – but I’ve yet to have a climate scientist say it is – have been more like dominoes falling than a concurrent collapse. This time, it is the opposite: Mostly all the dominoes falling at the same time.

    This seems like enough reason to push the sensitivity higher.

  5. 5
    Jutta Paulus says:

    Could it be connected to the fact that most models don’t take the actual shape of the “grid” into account (as far as I know)?
    I have read somewhere that models use “cubes” in the atmosphere, but obviously, if you span a web of 50*50 km across the globe and look at effects up to a height of 10.000 m, the base on the ground has an area of 2500 km2, whereas the “upper” area is 0.3% (approx.) larger.
    Could you enlighten me whether this is correct?
    And may it play a role in model bias?

  6. 6
    Uli says:

    Gavin,

    I think a possible source for a too high sensitivity may be in the short wave infrared solar radiation transfer code. This may be explain perhaps a part of the increased sensitivity for some models.

    If the radiation code for the atmosphere is improved, using a higher spectral resolution or a newer HITRAN version for the water vapor lines, usually the lower atmospheric infrared absorption of solar radiation increases and so the SW feedback due to increased water vapor.

    If now the surface albedo is not calculated at the same higher spectral resolution as the atmospheric part, then this would give an unrealistic low surface albedo over wet surfaces (ocean and other).

    This is due to the following. The albedo over the ocean is very low due to strong absorption of water at many wave lengths, were between this absorption lines the albedo is much higher then averaged over large parts of the solar near infrared.

    But with more water vapor in the atmosphere, which absorbs the solar radiation at the same wave length than water, the spectrum of incoming solar radiation chances at the surface. Therefore only solar radiation which is mostly not absorbed by water and water vapor reaches the surface increasing the surface albedo compared to solar radiation spectrum without absorbed water vapor lines.
    If now the surface albedo is not calculated at the same spectral resolution as the atmospheric part, this increase in surface albedo is underestimated.

    Therefore this would increase the short wave water vapor feedback and the climate sensitivity to too high values.

    In the worst case, using only broadband surface albedo for the near infrared solar part of the radiation, this effect could be very large and increasing the climate sensitivity f.e. from 2.5 to 4 K/2xCO2 (crude estimation by me) or so.

    Do all models use the same spectral resolution as in atmosphere for calculating surface albedo, or may be some updated the atmospheric radiation code and/or water vapor lines without chancing the near infrared surface albedo code?

  7. 7
    tamino says:

    Gavin, you are a fine writer.

  8. 8

    Appreciate the update–particularly as we may confidently expect denialati to use this conflict to spread FUD, including conspiracy theories that modelers are intentionally ‘juicing’ models for political purposes.

  9. 9
    Dan DaSilva says:

    4 Killian
    “This seems like enough reason to push the sensitivity higher.”

    Good point and that is being done.

  10. 10
    Russell says:

    Uli, sea surface albedo is more easily averaged than mapped in real time at the scale of model pixels, and is complicated by some well known unknowns.

    It can vary locally in the first decimeal place with wind velocity, cholophyl concentration in the water column and plankton concentration, as can boundary layer and lower troposphere responses to such anthropogenic forcings as sea lane ship wqkes and cloud nucleation.

  11. 11

    Climate Sensitivity seems such an important concept. Amateur that I am, the definition seems to start at greatly simple and then moves directly to incomprehensibly complex.

  12. 12
    Dan DaSilva says:

    4 Killian’s rationale for higher ECS is a distillation of the current reasoning in climate science.

  13. 13
    Gareth S Jones says:

    Just wanted to clarify that the Hardiman et al paper also describes an approach that corrects for the prescribed ozone having inconsistencies with the tropopause in warming climate simulations.
    This approach was applied to the HadGEM3-GC31 standard forced experiments that are published in CMIP6.

    [Response: Thanks! – gavin]

  14. 14
    O. says:

    Sensitivity? Or already the feedback loop?
    Given a certain feedback loop, will sensitivity increase, when coming nearer to the tipping point? (I would guess so.)

  15. 15
    O. says:

    @Nemesis, #2: “faster/higher/hotter”

    Deichkind – Denken Sie Groß
    https://www.youtube.com/watch?v=cnEQja0jBXs

  16. 16
    mike says:

    What Killian said at 4: there is no corollary in history to match AGW except possibly, an impact event. A lot of the reluctance of the scientific community to estimate the speed and impact of events is rooted in the sound practice of understanding climate by looking back through the record through ice cores, etc. There will only be the occasional blip, like the younger dryas that can help us understand climate change at the rate that has been triggered by our pulse of CO2e into the atmosphere.

    How are we doing on CO2? If you look at the keeling curve, we have precisely nothing to change the trajectory so far. I know that lots of us have done lots and many of have done something, but the numbers are plain:

    Oct. 27 – Nov. 2, 2019 409.32 ppm
    Oct. 27 – Nov. 2, 2018 406.43 ppm
    Oct. 27 – Nov. 2, 2009 385.06 ppm

    We better hope we come up with a cheap way to suck a lot of CO2e out of thin air and sequester it. We should do that soon, like yesterday.

    Warm regards

    Mike

  17. 17
    nigelj says:

    Dan DaSilva @9 &12, do you have any evidence to back up your lies that climate sensitivity is being decided on issues around system collapse? Of course not. You never provide evidence of anything. And your attempt to water down your obvious lie @9 to a lesser lie @12 doesn’t escape me.

    While Killian’s idea goes too far, hes right we are seeing some signs of multiple systems collapses. It’s almost like we need a measure of the level of ecological sensitivity to warming, and as a starting guess I would say its rather high.

  18. 18
    Karsten V. Johansen says:

    Killian of course is right that there are no really comparable earlier examples of the rapid development of climatic forcings, that we are experiencing with the industrialization based on rapidly/exponentially growing burning of fossil energy resources during the last couple of centuries. It has been shown by paleoclimatic research that the current growth rate of CO2 in the troposphere is around fifteen times higher than was the case even in the late Permian mass extinction (252 ma BP), when the rise of an enormous mantle plume underneath what is now Siberia east of Ural created massive volcanism whith magmatic eruptions burning through huge layers of hydrocarbons. We know no previous examples of any comparable amount of external radiative forcing being applied nearly so extremely rapid to the global climate system as our ongoing. And yet what we know from a wide range of slowly developing natural forcings both in the near and more distant past https://www.nature.com/articles/ncomms14845#f4 , does definitely *not* point us towards the still overwhelmingly practiced belief in business as extremely usual among 95 pct. of the ruling elites and at least nearly 50 pct. of the populations – all the sleepwalkers.

    Darkness at noon is our bleak political reality: https://i0.wp.com/runelikvern.online/wp-content/uploads/2018/06/fig-1-world-energy-consumption-1800-to-2017-vs-world-gdp-1980-to-2017-e1528939247704.png?ssl=1 The wordings from all the usual suspects only point to their bottomless cynicism and stupidity.

    Our paleoclimatic knowledge one would expect to cause big uncertainties about our ongoing and more and more risky global and fullscale climate experiment (russian roulette rather), and also extreme caution with the calibration and use of the climate models. They are all extremely simplificated compared to the real thing, which we only know from paleoclimatology and modern instrumental measurements. It seems to me that just as is the case with economic modellers, most climate modellers are all too much in love with their mathematics, and know and especially: care too little about paleoclimatology and modern, especially recent, measurements of trends, which are our only reality checks after all.

    James Hansen fortunately is a very important exception from this rule, and interestingly his results definitely point towards the higher end of climate sensitivity. It is also obvious that the IPCC, contrary to the established mainstream media mythology, in a number of cases rather systematically have been *underestimating* and not overestimating the speed of the developing global climate crisis. Noone who has read “Amusing ourselves to death” (Neil Postman, 1985) and/or has just a normal amount of real life outdoors and practical experience plus some historical knowledge can be surprised by that. Already the swedish author August Strindberg around 1900 denounced the media in his times as “the public lie”, and his norwegian contemporary Henrik Ibsen wrote the play “An enemy of the people”, where the truth about local seawater pollution is being suppressed by the local newspaper for reasons of profit (it was also Ibsen who created the expression “life-lie” to characterize the modern bourgeois/liberalistic view on society and the socalled law of progress).

    As has been said about the IPCCs “summaries for politicians” (which are the only pages from the IPCC being read by journalists, it’s of course therefore they are being made): they constitute a kind of carefully worded cover-ups heavily influenced/censored by the fossil fuel etc. corporations through their US, saudi, EU etc. political proponents (which are in fact nearly all powerful politicians from the Clintons to the Trumps and from the European Commission to the House of Saud, the chinese central commitee, the russian, brazilian… oligarchs , indian moguls etc.) They should rightly be called summaries by the ruling elites and their clandestinely (and among themselves more openly) denialist politicians. As has been said by Greta Thunberg: the climate don’t need all their empty words. These politicians and their handlers only believe in money, they only pretend to listen to the science, and logically more and more often not even that: Trumpism is the logic outcome of reaganomics/monetarism = the old Manchester liberalism anno 1820.

    It is (has for quite a while now been) time for the climate scientists to tell the truth. We know more than enough to act, we have known that for at least twenty years now.

    https://news.mongabay.com/2013/05/last-time-co2-hit-400-ppm-temperature-was-8c-warmer-seas-40m-higher-than-today/

    “The time for procrastination is over” (Churchill 1936). “None are more hopelessly enslaved, than those who falsely believe themselves to be free” (Goethe).

  19. 19
    Al Bundy says:

    DDS: 4 Killian’s rationale for higher ECS is a distillation of the current reasoning in climate science.

    AB: Yes. When results don’t match expectations climate scientists look for possible explanations to test. Killian’s right. Nemesis is right, too. Lots of ways to look at it. For example, biological systems build up diversity over time. Bottlenecks tear down diversity. So, hypothesis: Gaia’s balancing act is seriously degraded by three or four bottlenecks occurring without enough time for diversity to rebuild between them (geologically simultaneous dominoes). The resulting extinctions and near-extinctions can alter climate. Plan: ponder, test, ponder, test, and ponder again until the results are explained.

    In contrast to scientists, DDS retreats to his mantra, “Reality MUST bend to my pre-conceived-with-zero-expertise beliefs”.

  20. 20
    AIC says:

    “…We probably won’t find out for a while…”
    To state the obvious, we are running the experiment.
    So if (or when, shudder) our planet gets to 2x CO2, we will know which model is closest to reality.

    Heard at a conference today: “All models are wrong, but some models are useful.” (I’m sure many of you are already familiar with it, but decided to repeat it.)

  21. 21
    Dan DaSilva says:

    “It is worse than we expected.” At some point years ago, this became a repeating pattern. What glitch in the system caused this? Many people know the answer.

  22. 22
    Dan DaSilva says:

    17 nigelj
    nigeli, I have been watering down a lot with Gavin as the moderator. Could you please explain how reply 12 is a lesser lie than 9. Not that either is a lie, I just want to understand your perspective. I need this information in the battle to defend the sanctity of logic over emotion in science.

    20 AIC
    “All models are wrong, but some models are useful.”
    The key is useful by who and in what way.

  23. 23
    Dan DaSilva says:

    19 Al Bundy
    Al, I know I promised not to respond to your replies but it looks like you have made an honest attempt at what passes as logical thinking for a person of your capabilities. Let me assure you that Gaia will survive after the next large meteor hit, nuclear winter, or total extinction of human life for whatever reason. You seem to think that will be caused by CO2. That is possible but let us not corrupt science in an attempted to save humanity.
    I am giving you the benefit of the doubt and I am assuming that your motivation is pure and is not a post-modern Marxist fantasy of the ideologically captured mind.

  24. 24

    DDS, #21–

    “It is worse than we expected.” At some point years ago, this became a repeating pattern. What glitch in the system caused this? Many people know the answer.

    Many people certainly think they know the answer.

  25. 25
    nigelj says:

    Dan DaSilva @22

    My perspective is really straight forward. You provide some evidence to back up your assertions about the climate sensitivity issue, and I will then explain why I think your second lie is slightly smaller than your first lie. This is a science website, so the least we should expect is people back up their assertions with evidence and your record is pretty dismal.

  26. 26
    Clyde Spencer says:

    Uli @ 6 said, “The albedo over the ocean is very low due to strong absorption of water at many wave lengths,…”

    It is more complicated than that. Smooth water has an ‘albedo’ that varies with the angle of incidence. Further, the reflectance approaches the spectrum of the source (sun) as the angle of incidence approaches 90 deg. That means the depth of the absorption features decrease and approach a limit of zero at a glancing angle.

    https://wattsupwiththat.com/2016/09/12/why-albedo-is-the-wrong-measure-of-reflectivity-for-modeling-climate/

    Strictly speaking, the reflectance as calculated with Fresnel’s Equation is a function of the complex refractive index, which is related to the absorption at specific wavelengths.

  27. 27
    Dan DaSilva says:

    20 AIC says:
    “So if (or when, shudder) our planet gets to 2x CO2, we will know which model is closest to reality.”

    Not quite, if we reach 2X CO2 and everything remains stable (which is impossible) and we wait until the earth’s temperature is stable we will have a guess at what model is closest. Note: This assumes we have some idea what percentage of the earth’s warming is caused by CO2 (which we do not).

    Of course, by that time there will be many newer models with many different estimates and nobody will care about CMIP6 (which is the correct assessment).

  28. 28
    Al Bundy says:

    DDS,
    Only a moron would decouple humanity’s future from the decision-making process. Yep, slime will survive AGW. To crow about that is evidence that you’re sl***.

    And please stop pretending that you fathom anything about my capabilities. Self made morons deliberately avoid comprehension. Preconceived gotchas drive their psyches. Seriously, have you ever created or even said anything original?

    Time to double down. Explicitly say that as long as bacteria survive you don’t care about multicellular life, let alone sentient life…

    Hmmm, that makes sense. Why would the adamantly anti-sentient care about humanity?

  29. 29
    Dan DaSilva says:

    Al, sorry for the mild insults and rough treatment but they were required to get to the truth.
    You are very very close but not quite there yet. The statement I am looking for is more like:

    Only a moron would decouple humanity’s future from the scientific process.

    I think you are very smart and well-read. You are probably as intelligent, well informed. passionate as climate scientists. In this case, I believe your motivation and reasoning are the same. Which solves the mystery (of reply 21) as to why every climate finding is “worst than expected”. The answer is: the narrative must be pushed.

    The motivation may be post-modern Marxist theory but I will assume the more chartable option of saving humanity.

  30. 30
    Robbie says:

    re: Mike #16

    I recently read the book Smart Solutions to Climate Change and there’s good news in there.

    For a worst case scenario it looks like there are a couple of easily apprehendable backstop techs. In fact they really don’t have to be backstops but we can consider them that way for the time being – not only because they have a political downside as climate engineering solutions but also because from what I’ve read warming will be an overall positive at least until 1.5 degrees. (a ~2010 average of cost/benefit estimates had the tipping point at 2 degrees, estimates of costs have risen since then)

    We know stratospheric aerosols would work and the book’s climate engineering chapter estimated the cost benefit ratio of an aerosol project to be around 30-1. The best non CE option in the book had an 15 – 1 benefit to cost ratio estimate. Probably better than that would be Marine Cloud Whitening, not as proven but likely vastly cheaper resulting in estimates of around a 7000 to 1 benefit cost ratio. That didn’t take into account potential negative side effects but it also didn’t account for positive side effects. For instance cloud whitening would have a local effect allowing for north pole and/or tropics specific targeting. Because warming may already be a net negative for the tropics cloud whitening could be used immediately – but it may reduce rainfall so it may still not be a good option for the tropics at least until higher temp levels were reached.

    The non CE solution that stood out in the near term was research and development of energy technology. This was rated at a 15-1 benefit to cost ratio. The other ideas ranged from negative benefits to around a 4-1 BCR. In the long run climate economists seem to be unanimous in recommending a carbon tax but that has two problems. First it’s not a very effective near term solution, because warming costs mostly happen in the last half of the century so carbon taxes seem to be recommended to start quite low. In terms of the next few decades a carbon tax represents what may be a difficult political fight without much punch. Secondly for it to be effective long term it has to be applied basically evenly worldwide so it’s an uncertain policy.

    R&D would have a much more direct and immediate impact on future carbon emissions trajectories and any single country or small group of them could work on it. Where I don’t see a developing world carbon tax happening any time soon, richer nations could foot the entire bill for an R&D program. The recommended spending level is up to 100 billion a year. That compares to the Paris Accord which is unlikely to be followed, and if it did would cost 1 – 2 trillion a year worldwide with far less total benefits than would be likely from R&D.

    R&D has another strong point in that there’s really no reason to oppose some level of it even for a climate skeptic who expects an ECS of closer to 1 degree. The payoff in reduced fuel costs vs. carbon fuel sources of some new technology could pay for the R&D costs in itself and potentially displacing coal power would be an unquestionable benefit.

    So if anyone’s still reading this, quick takeaway – the best immediate climate policy is energy R&D of up to 100 billion a year worldwide, around 30 billion for the US. More research into Marine Cloud Brightening and climate engineering would in theory be even better than that and definitely good to test out.

  31. 31
    Dan DaSilva says:

    Al, Quote “Time to double down. Explicitly say that as long as bacteria survive you don’t care about multicellular life, let alone sentient life”

    I respect most all life and love humanity and therefore I would save humanity by coupling (not decoupling) humanity’s future to the scientific process and damage that process as much as I felt was required.
    Do scientists love human life as much as I do? I think they do.

  32. 32
    JPC Lindstrom says:

    So why can´t the model INMCM5 join and play with the others? To me it seems to do extremely well and without using rather unrealistic (high) ECS values. Perhaps because of its inherent treatment of ocean oscillations (it doesn´t need CO2 to explain everything).

    https://www.earth-syst-dynam.net/9/1235/2018/esd-9-1235-2018.pdf

  33. 33

    DDS 27: This assumes we have some idea what percentage of the earth’s warming is caused by CO2 (which we do not).

    BPL: When I regress temperature on carbon dioxide for 1850-2018, I get about 82% of variance accounted for. I would guess it’s nearly 100% of the trend.

  34. 34
    Al Bundy says:

    DDS,

    First you crow about how the planet will exist even if you guys kill youselves off and then you wax on about your love of humanity. Uh, which is it?

    And then you pretend to value science-based policies! Dude, “denier” ain’t a badge showing impartiality. You actually said that the fact that the data consistently shows that the consensus has yet again underestimated the problem shows that it’s all a hoax, or goop or whatever.

    Dude, the data that would support your claim would be data that consistently shows that things aren’t as bad as we think. I’m betting that you’ve received close to zero evidence for your smear.

  35. 35
    nigelj says:

    DDS @29 says “I think you (AB) are very smart and well-read. You are probably as intelligent, well informed. passionate as climate scientists. In this case, I believe your motivation and reasoning are the same. Which solves the mystery (of reply 21) as to why every climate finding is “worst than expected”. The answer is: the narrative must be pushed.”

    AB is smart, but your conclusions are illogical and unfounded. You have provided no real evidence of any narrative being pushed, just sophistry. There’s a far more obvious and simpler explanation for things being worse than expected. Not every climate finding is worse than expected, but those that are worse are most probably worse because models are not 100% perfect. Modelling is good, but looks a bit too conservative, the complete opposite of what the deniers allege. This is the simplest and most logical explanation, and in this case Occams Razor would be right.

    ———————–

    Dan DaSilva @9

    “This seems like enough reason to push the sensitivity higher (we are experiencing simultaneous significant systems change)”

    “Good point and that is being done.”

    I repeat you have provided no evidence “it is being done”.

    Imho climate sensitivity is not calculated and cannot be calculated on the basis of considering systems change in the biosphere etcetera or a jump in melting rates of glaciers etc. I’m not an expert on any of this by a long way, but I know climate sensitivity tells us about temperatures for a doubling of CO2, and is a function of radiative forcing, so its about the physics of that especially feedbacks. Systems change does not provide reliable information on where to set climate sensitivity. This is because you could in theory have considerable system change for quite LOW or MEDIUM climate sensitivity. Systems change just tells us a certain level of warming has certain implications, and it looks like even 1 degree of warming has more serious implications than has been thought, but I detect that you know all this.

    However climate sensitivity could be high, and a lot of the latest modelling suggests it is high. Modelling improves over time like anything else.

  36. 36
    nigelj says:

    Robbie @30, don’t take the book “Smart Solutions to Climate Change” by Bjorn Lomberg as gospel truth. I suggest you read his bio on wikipedia to discover why we should be sceptical about anything he says, saves me repeating it. But note he is a political scientist and statistician, not a physicist, climate expert, economist, or engineer.

    Sucking C02 out of the air works, but is expensive and would require enormous areas of underground storage and absolute bucketloads of technology. It would need unprecedented international cooperation, although so does renewable energy.

    Geoengineering with aerosols has known and unknown side effects. It would be an untried experiment on the whole planet and could go horribly wrong. Local trials of this technology would only tell us so much. So yes by all means people should research these things, but imho they are no substitute for cutting emissions.

  37. 37
    Mr. Know It All says:

    “The US federal government goes to quite a lot of effort to (mostly successfully) keep sensitive but unclassified (SBU) information (like personal data) out of the hands of people who would abuse it.”

    Two comments:

    1 – If you’ve ever applied to a federal gubmint job, you probably got a notice in the mail about their website being hacked, with an offer to pay for your Lifelock membership.

    2 – Maybe classified data is safer if stored on a personal unsecured server in a closet? What kind of idiot would do that! ;)

  38. 38
    Al Bundy says:

    DDS,
    “Love” requires the absence of compartmentalization. So, no, you do not love humanity because you limit said love via compartmentalization.

    Me? As a follower of the most famous and beloved psychopath in fiction, Star Trek’s Mr Spock, I couldn’t care less about your species’ future, but my calculations as driven by the defined goal result in a sort of artificial love.

    Perhaps that will change if and when I achieve first intimate contact with full humans.

  39. 39
    anonymous says:

    Hello, if it turns out that CMIP6 is a false alarm, this is a wonderful news. The verification must be objective but just imagine if you had to announce in 2021 that we are facing +7C in 2100! Hope in the meantime that some are doing progress in stratospheric seeding because simply considering +4C in 2100 could signify +6C in 2200 if we do not try anything…

  40. 40

    DDS, #27–

    “This assumes we have some idea what percentage of the earth’s warming is caused by CO2 (which we do not).”

    We don’t know precisely. But we do certainly have ‘some idea’.

    It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in GHG concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period (Figure SPM.3).

    (Which last is also close to what BPL came up with for a longer period in #33, interestingly enough.)

    https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf

  41. 41
    Jai Mitchell says:

    Caldwell’s emerging constraints paper showed that of the satellite observable trends in tropical water vapor that could be confirmed with direct observation (there were 4 out of 9 total) the models that correctly reproduced these systems had ECS values typically greater than 4 and some as high as 5.3K. https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-17-0631.1

    The main issue is whether or not the historic trend in aerosol impacts have been accurately reproduced in the models, this is especially true for the period between 1920 and 1990 but also may be for prior to WWI. There is indication from innovative satellite observation work that the negative forcing from aerosols is much, much higher which would also indicate a much higher ECS/TCR.
    see: https://www.sciencedaily.com/releases/2019/01/190122104611.htm

    What I find more interesting at the moment is that the higher ECS models seem to have a higher TCR/ECS value than previous ones that were about 0.45. For example the UKESM1 TCR/ECS looks to be closer to 0.55 This would portend a similar climate response to the 95th percentile runs from Shindell & Smith (2019) paper from about 2 months ago that showed we had a committed warming of about 2.5C today under reasonable mitigation scenarios.

  42. 42
    Jai Mitchell says:

    For what it is worth,

    We are currently at 41 ppm CO2
    The oceans reveal an energy imbalance of ~1 watt per meter squared over the entire surface of the planet
    we know that aerosols from human activity are shielding the planet from a significant amount of energy between 0.5 watts per meter squared and as high as 1.5 watts per meter squared.

    There is a significant lag in the near term climate equilibrium so we have significant warming still in the system, at current levels of forcing from greenhouse gasses.

    we are currently at 1.2 degrees centigrade above pre-industrial levels.

    we know that at 2C above pre-industrial, we will start to experience ice free arctic conditions in the Arctic summer that will further amplify this warming.

    At this point any ESM that reproduces an ECS that is less than 3.0K must be thrown out of the mix simply due to conflict with direct observations.

    Even if Entimann shortwave forcing of CH4 is taken into account in the SLCP mitigation analysis.

  43. 43
    Dan DaSilva says:

    Barton, remember that correlation is not causation.
    One way to verify your findings would be to get a time machine then go back to 1850 and drop off Greta Thronbeg (She would browbeat everyone so bad that all C02 production would stop for good.). Then go forward to the present and see what the global temperature reading is.

  44. 44
    Dan DaSilva says:

    25 nigelj Quote: “My perspective is really straight forward. You provide some evidence to back up your assertions about the climate sensitivity is”

    The variations in the “climate sensitivity” of climate models are my evidence and I never assert what the actual climate sensitivity is. Please read my responses if you want to give me a more constructive form of input. However, what you are doing is fine also.

  45. 45
    Dan DaSilva says:

    24 Kevin McKinney
    What is your best guess? I think I have stated mine. It is the same reason as:

    * the reason models overpredict temperature
    * the reason adjustments lower past temperatures
    * the reason polar bears are dying off but they are not
    * the reason more CO2 is bad for plants but it is good
    * the reason ocean records are modified to show more sea-level rise
    * and the reason every new finding is “worse than expected”

    I will stop there because the moderation is unstable and I do not wish to spend a lot of effort just to be placed in the borehole.

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