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dana1981 at 07:27 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
"Indeed, it was featured prominently at WUWT.
Just pathetic that WUWT uncritically reposts this utter garbage, their readers eat it up with a spoon, and they expect us to consider them skeptics. I'd really love to know what TSI data Soon and Briggs used. ACRIM generally finds the biggest TSI increase in recent decades (still essentially zero). I downloaded the data (from here), and it shows essentially zero trend from 1979 to 2000. The Soon and Briggs plot on the other hand shows about a 1 W/m2 TSI increase over that period. It's nonsense. -
adrian smits at 07:10 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
The area north of 80 degress will never be ice free. It has actually cooled a bit in the last 50 years!Moderator Response:[DB] "It has actually cooled a bit in the last 50 years"
Simply making things up does not assign you any credibility. Unless you have a source for this unsupported assertion?
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John Hartz at 07:04 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
@GeoffChambers #142: Dang, you broke the code. You should seriously consider applying for a job with MI5. Then again, you may already work for MI5. -
Bob Lacatena at 07:01 AM on 9 September 2012A detailed look at climate sensitivity
Eric, You are very confused. If you insist on pursuing this course, I strongly suggest that you read a copy of K&H (link in the post above), and also find and read copies of each of the studies included in K&H, so that you will then know which studies did or did not use what sorts of models or observations, what their range of estimate was, what the certainties/error bars were, etc. [You are on the right track by noticing that there is no probability function in some of the estimates, because yes, they did not use models or have a broad sampling of statistical data, and so their estimate was as simple as a low and a high value with a best guess. But again, your propensity to then immediately gravitate to the low values and ignore the rest is indefensible. Denial, plain and simple.] -
Bob Lacatena at 06:53 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
MarkUS, Just my opinion, but I wouldn't think so. What is surprising about the cryosphere right now is the unexpected rate of change, but in the end what we care about is climate sensitivity. What we're seeing in the Arctic will almost certainly result in positive feedbacks happening sooner and boosting temperatures sooner, but those feedbacks are basically "already included" in the estimated 2 to 4.5C climate sensitivity. If you want to talk about an actual temperature projected for any specific year based on a model ensemble, then yes, they may need to be adjusted upwards because the models did not predict an Arctic collapse happening this fast. But the expected end result -- the warming from X CO2 -- should be about the same. -
Bob Lacatena at 06:46 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
Dirt Girl, Like I said, just look for Lief's comments. They're vary short, simple and to the point, a lone voice of reason in a rather wild jungle. And he almost always provides links to supporting data. Right from the start you can see that the Soon/Briggs TSI graph bears absolutely no resemblance to reality, and in fact its hard to figure out how they got it to be shaped so close to the temperatures in question (especially when those temps are only the special 2% of the Earth that is the USA). Then of course there's always the question of why, even on their graph, as TSI goes down in the last 20 years, temps keep going up. Lastly, for fun you can read all of the nutter comments from the WUWT regulars (particularly those aimed at Lief for having the temerity to try to point out the obvious problems with the article). -
Eric (skeptic) at 06:36 AM on 9 September 2012A detailed look at climate sensitivity
I just found an old reference ice age climate forcings and I am a little low in GHE forcing from G to IG, but probably not enough to matter much. -
Eric (skeptic) at 06:33 AM on 9 September 2012A detailed look at climate sensitivity
Sphaerica, yes, there is no other way I know of to obtain the curves that look like PDF's in the figure above. In some cases there is no curve (volcanic, LGM data, LGM models) which means there was one model run or no model runs (just an energy balance type of calculation for before and after the climate change and apportionment to CO2 and other forcings and feedbacks). Michael, you are correct in general that my estimate made dfrmo the low end of paleo data is lower than most experts in the field and I repeat from above that there are possible positive feedbacks that I am not considering when making that estimate since those are untested and unrepresented in the paleo data. But I would not combine the "PDF" evidence the way they did because I do not believe they are independent or PDF. The relevant numbers for estimating the range of sensitivity (S) are the CO2 rise from 190 to 280 with a corresponding temperature rise of 6C. The rise is a little under 1/2 of a doubling so that gives an upper bound of 12C for S. Looking raw forcing changes, albedo is 3.5 W/m2, dust is as much as 1 W/m2 and CO2 is 2 W/m2. Weather changes create energy balance changes too (although people here have argued otherwise), but for this argument we will assume that all weather changes that affect S for G to IG also apply to S from present to doubled CO2. From that evidence there is roughly 1C change per 1W/m2 of forcing. That would then imply 4C for S. But unlike glacial to interglacial, there is not a lot ice albedo change left in the current climate. Assuming there is none and no contribution from reduced dust, that cuts S to 2C. But uncertainty in glacial forcing will make that estimate lower. For example if stronger winds during the glacial period caused more net cooling (see the diagram in my post 94) then then S going forward will be lower unless average winds increase. Likewise S will be lower if factors like glacial dust were underestimated. -
Doug Bostrom at 06:29 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
Once again we find that a broken clock can occasionally tell us the truth without actually being a working clock. Geoff: Social scientists are making enormous hidden assumptions about the psychology of their respondents when they put their trust in this sort of exercise. Spot-on, Geoff, you're exactly correct. Social scientists employ methods invisible to and distrusted by you because you've not spent the time necessary to understand how social scientists work. Beg, borrow or steal a research methods syllabus from a PhD social sciences program, follow the readings therein, let the shades fall from your eyes. Who knows? Your intuitions might be correct but without getting your game on you'll never be able to do more than guess, let alone usefully articulate your thoughts. -
geoffchambers at 06:11 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
#138 John HartzTom Curtis: Recommend that you post a survey on this thread asking our readers if their eyes glaze over when they see yet another GeoffChambers post.
Call me a conspiracist, but that sounds like a coded warning to Tom not to fraternise with the enemy. Yes, I’ve read the deSmogasbord blog. Fair made my mouth water. -
Mark-US at 05:40 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
I'd like to repeat a question I asked last week in another thread..... does the unexpected early loss of albedo in the cryosphere mean the overall temperature projections for the various SRES scenarios in AR4 (2007) have to be adjusted upwards? The only response comment was the sweeping observation that AR4 is out of date. Well, that's obvious just from the much faster than expected ice loss, and its easy to just make an assumption that the projected temperature ranges have to go up since we are reflecting less solar energy. But let's not assume. Did the AR4 models have sufficient flexibility to accommodate the sudden loss of albedo? Or if we revise the models to match observations, do the models pump out different projected temperature ranges? -
chuck101 at 05:34 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Eric, Try opening your eyes. Arctic ice area extent is falling off a cliff. It has lost 45% of it's area in the past 30 years and more of it's volume. Why do you suppose that is happening? Or do you not accept that it is happening until your arbitrary conditions are met? If you have to wait a couple of decades for before you will acknowledge AGW where will the world be then? The loss of the arctic ice cap, which could occur in the next ten years, will have incalculable consequences, and you are still worried about low CS-inducing Arctic dust? As I said, you have it ass-backwards -
John Hartz at 05:34 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
Sphaerica: I figured if I posted a link to Readfern's article, GeoffChambers might not have time to post comments here. It's an obvious dilution tactic. On the other hand, Graham Readfearn may not be pleased. -
Bob Lacatena at 05:20 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
John! You showed them the secret sign! With the secret logo! Doing the secret hand wave! You're going to blow the whole conspiracy wide open! Quick, quick, delete that comment! -
Bob Lacatena at 05:18 AM on 9 September 2012A detailed look at climate sensitivity
Eric, you seem to be playing with words. First you say the probabilities presented by K&H are dismissed because they "are not actually PDFs but model run density functions". When presented with this inaccuracy, that much of the data is not model based, you say "the data is depicted in distributions.... I do not see any way to arrive at a PDF... without a model". So the probabilities presented by K&H are dismissed because they are either model based or else because it must be model based, because you personally don't know how they could determine a range of probabilities in any other way. Is this correct? Is this your stance? So with one sweep of the hand you dismiss thirty years of climate sensitivity studies because, in your mind, it must have come from models and you don't trust the models. How can you not recognize that your own thought patterns are based 100% in total, irrational denial? -
Dirt Girl at 05:18 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
Thanks for the responses. I try to avoid WUWT since it tends to be filled with more rhetoric than science. I didn't want to accuse them of the highly unethical practice of fabricating data without a little background checking. I find it interesting that the crew at WUWT constantly accuse the scientist of constantly making data up. In the one incidence where this has happened in my experience, the person was fired immediately. I doubt many of the people commenting there have ever actually worked in the scientific field. Fake data does not fly. -
dhogaza at 05:15 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
"Unless the models can accurately predict all this evidence (to his own arbitrary standards), we can't be sure that it is happening. Or did I miss something?" As others have said - no. He provided a link to a thread at real climate posted six years ago, arguments he's repeated in every thread he's participated in here. Nothing will convince him that perhaps experts in climate modeling must might know more about the subject than he does. The attributes listed in the OP should include something regarding "a stubborn refusal to abandon a position in the face of all contrary evidence". -
michael sweet at 05:05 AM on 9 September 2012A detailed look at climate sensitivity
Eric, I note that the line in the graphic that says "combining different lines of evidence" shows the range 1.5-5.0 C. That means 1C is 1% or less. Your argument puts you strongly in the denier campp. Please show me again how you arrived with 1C as the most plausible result. 7C is at least as likely. -
dhogaza at 05:05 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
"That is where I do not believe the models have the fidelity to make an accurate projection." On the other hand, you're certain that *you* have the "fidelity" to claim a climate sensitivity on the order of 1C per CO2 doubling. This is an interesting asymmetry I see all the time in the denialsphere - everything claimed by climate science is far more uncertain than climate science claims. Yet the denialist is 100% certain that feedbacks are overwhelmingly negative (look at your latest, Eric - "Along with such severe weather I am interested in how much negative feedback is caused by that severe weather if in fact it increases on average" - the rest of us might first be interested in undertanding the *sign* of the feedback, and later the magnitude, rather than assume it's negative). And the denialist is therefore certain sensitivity to the doubling of CO2 lies far below the lower end of the accepted range (about 2C). -
Bob Lacatena at 05:05 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Let's get this discussion back on topic. If Eric wants to participate, he can try to explain how his reactions here differ from the "knee-jerk science rejection" that headlines John's original post. Eric, your position is at odds with all of the science. The details of what you disagree with and why are not relevant in this discussion. What is relevant is how your behavior closely fits the pattern of what John Cook describes. -
Dikran Marsupial at 04:55 AM on 9 September 2012A detailed look at climate sensitivity
Eric, Your reply to my point about perturbed physics experiments is pure evasion. Of course one could perform a perturbed physics experiment on just one variable, and indeed climatologists often do, but that is entirely missing the point, as I think you know perfectly well. Peturbed physics experiments can be performed to investigate the range of plausible parameter values, which is an answer to your previous question. Frankly you should be ashamed of yourself. Well all here have better things to do than respond to this sort of sophistry. You have made it clear that you are not interested in answers to your questions, so I for one will stop supplying them. -
John Hartz at 04:35 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
Here’s another take on the Lewandowsky survey and the consternation it has generated within Ostrichville. “Research Links Climate Science Denial To Conspiracy Theories, But Skeptics Smell A Conspiracy”.By Graham Readfearn, DeSmog Blog, Sep 5, 2012 This graphic is embedded in it.
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Bob Loblaw at 04:25 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Eric@59 "the average conditions and dynamics are linked to each other ...yet you do not need to be able to predict every single drop of the ball on a roulette wheel in order to be able to predict how to set the odds so that your casino makes money. You are completely failing to recognize that long-term statistics of the system (either the real world, or a model of that world) are sensitive to different things within the system, compared to what the short-term patterns depend on. You desperately need to learn something more about systems. From what you have written, I do not think you understand what "initial value problem" and "boundary value problem" mean (from John's comment), and why the distinction is important. This seems to be a very common error that I see in people that come to climatology from a meteorology background (not that I'm saying this means anything about your background). -
John Hartz at 03:59 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
Tom Curtis: Recommend that you post a survey on this thread asking our readers if their eyes glaze over when they see yet another GeoffChambers post. I know that my eyes do. -
Eric (skeptic) at 03:44 AM on 9 September 2012A detailed look at climate sensitivity
Dikran, the perturbed physics experiments are interesting. One could do entire studies on just a single parameter, for example http://en.wikipedia.org/wiki/Entrainment_(meteorology) Michael, apart from paleo and volcanoes (similar to paleo), the data is depicted in distributions. When I read the methodology to turn observations into climate sensitivity estimates, for example, Wikipedia's description I do not see any way to arrive at a PDF (or something like it). If someone knows how to arrive at the PDF (or whatever) without a model, please let me know. -
Bob Lacatena at 03:37 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
3, Dirt Girl, You can get the core of your answers by reading the comments and following the links posted by Lief Svalgaard at WUWT. Short answer: Soon and Briggs manipulated/cherry-picked the data in a variety of ways to completely misrepresent things (using indefensible TSI data, using only US daytime high temperatures, etc.), and as partial evidence of this, note that their "submission" is merely an article published in the Washington Times, not a paper submitted to a journal, because it would get laughed out of just about every journal on Earth (except maybe E&E). Long answer: Look for the post. -
geoffchambers at 03:30 AM on 9 September 2012AGU Fall Meeting sessions on social media, misinformation and uncertainty
Tom Curtis #136 I agree absolutely that the probability is that the two outliers were attempts to game the survey, and that Lewandowsky should at least have indicated their existence in the paper. He should also have looked at the distribution of sceptics and conspiracy theorists by source blog - the most basic test of any organised attempt to cheat. I’ve been thinking further about the point I made at #130 about survey design and the legitimacy or not of various responses. Imagine the researcher (let’s call her Alice) doing a follow-up interview with a respondent whose questionnaire responses arouse suspicion (call him Humpty Dumpty) Alice: “I see you’ve ticked ‘Agree strongly’ to all the questions”. Humpty Dumpty: “That’s right. I always tick the left hand box when filling in an online survey.” Alice: “So these answers don’t represent your true beliefs?” Humpty Dumpty: “Yes they do. It’s my firm belief that I should always tick the left hand box.” Alice: “But you don’t really strongly agree...?” Humpty Dumpty:”Yes I do. I strongly agree with ticking the left hand box. If I didn’t , I’d tick the right hand box wouldn’t I? That’s logic.” ... and so on. The serious point is that an interview is an artificial construct which derives its legitimacy from its similarity to other experiences in our lives. If someone stops you in the street and asks you the way to the post office, you don’t think of lying, but answer to the best of your ability. If they added: “Do you think it’s to the left or to the right? You’re not allowed to say you don’t know” you’d probably feel seriously p*ssed off, and refuse to cooperate. Telephone interviews, and even more so online questionnaires, are more removed from the face-to-face situation where human beings normally interact, and feel the natural tendency to cooperate. Social scientists are making enormous hidden assumptions about the psychology of their respondents when they put their trust in this sort of exercise. -
Eric (skeptic) at 03:23 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Chuck101, the main reason for my focus is so there can be a discussion, although it's very difficult for me to avoid tangents into attribution, costs, mitigation, etc. The 97% includes models, but model treatments vary along with the result (Greenland melting versus Amazon drought versus storminess). chriskoz (and JohnMashey), the average conditions and dynamics are linked to each other. It's ok to put the average conditions from empirical data into a model parameter, but the conditions will change the dynamics downstream (time or location). For example we all agree that measurements show that CAPE is increasing on average and high CAPE will help sustain an MCS like the derecho that hit my area at the end of June. Along with such severe weather I am interested in how much negative feedback is caused by that severe weather if in fact it increases on average. That is where I do not believe the models have the fidelity to make an accurate projection. By fidelity I mean that the model need not predict anything correctly but must result in an accurate climatology that is an essential input to the energy balance calculation. -
Bob Lacatena at 03:14 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Eli, But we can't understand stuff from models because we don't understand enough stuff to build models that are good enough to help us understand stuff. Or so Eric seems to think. -
michael sweet at 03:09 AM on 9 September 2012A detailed look at climate sensitivity
Eric, Most of the data summarized in the table is observations, not models. There is a single line for models. Your claim "the apparent probability density functions are not actually PDFs but model run density functions" is simply incorrect and evidence of complete denial. Welcome to the 3%. The overwhelming majority of the data idicating a 3C sensitivity comes from direct observations, not models. If your claim to uncertainty is that observed data is modeled there is no room for discussion. -
Do we know when the Arctic will be sea ice-free?
vrooomie - Indeed, it was featured prominently at WUWT. -
vrooomie at 02:52 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
And though Dana and Daniel are correct, in their dismissing the findings of Soon and Briggs, I'll wager that, *as I type*, the denialiti are furiously posting their findings all over the Intertoobs. -
Do we know when the Arctic will be sea ice-free?
Dirt Girl - I for one am quite curious about the Soon and Briggs TSI - it isn't supported by any of the information I am aware of. They state the temperature data is from BEST, but do not source their TSI data. If you look at either the sunspot numbers or direct TSI measurements (averaged over the 11-year solar cycle for clarity) versus temperatures (as in this plot), you see that insolation is dropping while temperatures are rising over the last 40 years or so. S&B's claims are contradicted by the evidence. [ And yes, the Washington Times is a hyperconservative low-circulation paper, owned by the late Sun Myung Moon, not known for any balance in their views. I would not consider it a reliable source. S&B are welcome to try to publish their column in a peer-reviewed journal - it might give the editors a good laugh while getting rejected. ] -
vrooomie at 02:50 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
While reading the article, here's the point at which I fell off'a my chair, laughing... "...there has been relatively little work investigating the solar-climate connection." Riiiight. As for the rest of the article, and considering not only the source of the 'data,' but who published and printed it, I agree w/Dana@4 -
Daniel Bailey at 02:44 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
From a superficial scan of the article & graphic: - No baseline indicated -Data appears visually to end at 2005 (hey, BEST goes through 2010, doesn't it?)- The US is only a minute fraction of the world - BEST is land-only The only reason to not extend the TSI & temperature data later in the decade (using all the land data), and to ignore more than a century of OHC data, is that plotting such data would be inconvenient to reaching their predetermined narrative. The graphic is a crap exercise in curve-fitting, IMHO. -
dana1981 at 02:39 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
Dirt Girl @3 - we weren't planning on it. The Washington Times is a right-wing rag, and Soon and Briggs are not worth taking seriously. Note the graphic in question claims the temperature data are from BEST but does not provide a reference for the solar data. As you note, TSI data have been essentially flat since 1979, decreasing if anything. Basically the Soon op-ed is a joke and IMO not even worth debunking. -
EliRabett at 02:33 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
As important, if not more, is the ability of models to help us understand stuff. -
Dirt Girl at 02:22 AM on 9 September 2012Do we know when the Arctic will be sea ice-free?
Sorry, this is O/T but I was wondering if Skeptical Science will be posting a rebuttal to the Soon and Briggs Op Ed in the Washington Times yesterday. I am curious as to how the graph in the article shows and increase in TSI after 1970. Looking at the TSI from satellites or sun spot proxy data this does not seem possible. The graphs I've seen both show a decrease during this time period. - Thanks -
Wadard at 02:09 AM on 9 September 2012A vivid demonstration of knee-jerk science rejection
Shorter Eric: Humanity's saviour is low CS-inducing Arctic dust. Until that's all modelled I don't credit a thing. -
A detailed look at climate sensitivity
Eric (skeptic) - " I don't think "1°C is reasonable" but it is plausible." "plausible - Seeming reasonable or probable." You keep using that word. I do not think it means what you think it means. Given under the evidence the 90% probability of a sensitivity between 1°C and 5°C (and yes, that range does indeed represent the error bars on our knowledge), 1°C sensitivity to doubling of CO2 represents only a 5% chance - equally probable as a 5°C sensitivity. A 1°C sensitivity given our current knowledge is not plausible, it is possible but unlikely. You are claiming that a 1/20 chance is "probable", and that's just not supportable. Given the evidence, 1°C is not a good bet. -
Bob Lacatena at 01:24 AM on 9 September 2012A detailed look at climate sensitivity
Eric, Sorry, I don't see any further point to discussing this with you, as you seemed to be totally and completely trapped in the mind set that 1) The models are inadequate 2) Everything is based on the models 3) Therefore any conclusions are inadequate As long as you are trapped in this mindset discussion hopeless, and your perception of and opinion on anything will remain too narrowly constrained to allow for any reasonable progress in the conversation. Sorry, but I just don't see the point in discussing this with someone who turns every single discussion, no matter what the details, back to "the models are inadequate." -
Dikran Marsupial at 00:45 AM on 9 September 2012A detailed look at climate sensitivity
Eric: "The category of "very likely" (90%) encompasses the range from 1C to well over 5C in most cases, so it doesn't help much." This comment strongly suggests that you don't understand the probabilistic arguments. A 90% credible interval is the error bars. The fact that they range from 1C to 5C tells us that there is a large uncertainty in our knowledge of the correct value. This is exactly the reason that it is unreasonable to assume it lies as the low end, as that is pretending we are more certain than we actually have evidence to support. -
Dikran Marsupial at 00:40 AM on 9 September 2012A detailed look at climate sensitivity
Eric (skeptic) You are merely changing the subject. In a Bayesian analysis you start of with a prior state of knowledge (the ranges of the parameters) which you then combine with observations (in this case the model runs) which gives you the posterior state of knowledge. Thus the range of parameters is merely the prior state of knowledge, so it is hardly surprising that it is included in the analysis. The reason for specifying a plausible range is exactly because we don't know the correct value with high certainty. P.S. You might also want to investigate the purpose of "perturbed physics experiments". -
Eric (skeptic) at 00:36 AM on 9 September 2012A detailed look at climate sensitivity
Sphaerica, here are no error bars in the depiction above. All the depictions with a model run density functions are from models, the others are volcanoes and paleo-derived. Both have forcings other than CO2 and may not be applicable. The category of "very likely" (90%) encompasses the range from 1C to well over 5C in most cases, so it doesn't help much. The weaker "likely" category is mostly 2C and above. As for dangerous, I noted here that stronger storms are cooling (although I made a mistake, subsidence is cooling on average, not warming, so if there are fewer but stronger hurricanes on average, that means negative feedback). I don't think current sea level rise is dangerous other than model projections. Dikran, how can we say that a critical parameter (say convection) is reasonable or not? A sensitivity of 2C might be realistic, given a number of simplifying assumptions, see here But the required calculations from physics or empirical data to model parameter values are difficult to determine in any case. -
Dikran Marsupial at 00:04 AM on 9 September 2012A detailed look at climate sensitivity
Eric (skeptic) The "model run density functions" are probability density functions, and have a perfectly reasonable interpretation within a Bayesian framework. "The choice of ranges of parameters to mimic natural variation determines the shape of the distribution." Well of course they do, the "model run density function" is an indication of the relative plausibilities of different outcomes, given what we know, so naturally this would involve using realistic parameters rather than unrealistic ones! -
Bob Lacatena at 23:24 PM on 8 September 2012A detailed look at climate sensitivity
Eric, Your position is utter nonsense. First... you don't see error bars? Second... all you see is models? Third... so if the range is 1C to 5C, and anything from 2C up is dangerous (the higher the more dangerous), and it is possible, based on current events, that 1.5C is dangerous... ...then tell me again how you wind up at "let's be patient, because climate sensitivity is probably 1C"? Tell me again, too, how you can look at the K&H chart, with a marginal probability of a climate sensitivity below 2C, and see 1C as a shining beacon? Oh, that's right, they are "not actually PDFs" and you can't seem to see the bars and lines and words like "likely" and "very likely." And they're all models... including the "Instrumental Period" and the "Current Mean Climate State" and the "Last Millenium" and the "Volcanic Eruptions" and the "Last Glacial Maximum" and "Millions of Years Ago" and... -
Eric (skeptic) at 22:51 PM on 8 September 2012A detailed look at climate sensitivity
Michael, thanks for the challenge. I don't think "1C is reasonable" but it is plausible. As I explained here and previously, the apparent probability density functions are not actually PDFs but model run density functions. The choice of ranges of parameters to mimic natural variation determines the shape of the distribution. So I don't think it is reasonable to point to the center of "model density distribution functions" and claim that 3C is reasonable. The fundamental problem is sub-grid scale physical parameterizations which determine the density function, not reality or even simulated reality. More apropos to my previous post is that the paleo bars do not have any density function because there is really no way to know the distribution due to a lot of measurement error, localized measurements (ice cores) rather than global, changes in geography with large unknown effects, etc. One way to deal with some of the unknowns is by using models (e.g. feeding changed geography into the models). The full chart from Knutti and Hegerl is reproduced in post 72 above. It shows that the paleo estimates do not have a similar base state (far left red square in 3b) and do not have similar feedbacks and timescales (next red square). Those two red squares make the model estimates inapplicable to today's climate. To make them applicable, one must remove the uncertainties due to difficult-to-measure feedbacks. The result, at least in K&H08, is that the estimates of sensitivity from paleo data do not have a distribution, they could be uniform or more likely skewed left since other feedbacks also amplified the warming from glacial to current interglacial along with CO2. Today those other feedbacks are missing (e.g. dust, large weather changes, etc) As I said in the other thread there may be new positive feedbacks that were not in play in the glacial transition so that adds uncertainty on the high side. -
chuck101 at 22:43 PM on 8 September 2012A vivid demonstration of knee-jerk science rejection
Thanks for the in depth explanation chriskoz, though I think there is a simpler underlying psychological process going on here. Eric views himself as a rational skeptic, and would be embarrassed to get lumped in with the standard denialist crowd. Hence, he claims that he accepts the 97% scientific consensus. EXCEPT. Except that he won't until some arbitrary milepost of his own specification is met, which it wont be, at least for a decade or two. This allows him to present himself as rational, sane and objective, while still denying the consensus for the next 10 to 20 years. A denier in denial. Nice Work! Self contradiction appears also to be necessary for an accomplished denialist: http://www.skepticalscience.com/plimervsplimer.php -
Bob Lacatena at 22:24 PM on 8 September 2012A vivid demonstration of knee-jerk science rejection
52, chuck101. You didn't miss anything. It's "focused denial" dressed up as rational skepticism. -
chriskoz at 22:11 PM on 8 September 2012A vivid demonstration of knee-jerk science rejection
chuck101@52 You got it essentially right. Furthermore, if you follow the link in JohnMashey@43, you better understand the differences between the problems answered by weather vs. climate simulations. The problems of climate (the changes in the average state of chaotic processes) prediction is not limitted by model accuracy in representing the chaotic processes. What is important is getting the roundings correct (e.g. to have constant mass and energy balance) and the model stability within given boundaries in accordance with observations. Accurate representation of the dynamics of the chaos is less important. As an example, Eric wants the models to calculate dynamic convections to have faith that cloud feedback is well represented. I argue that such calculations, apart from increasing the complexity and be source of potential bugs, may not increase models' reliability more than simple parametrisation tuned with observations would do. Eric displays a typical skeptisism of a weatherman: lack of confidence in simple science about average conditions, because he's an acclaimed expert in underlying dynmical models. A simplified analogy would be: to figure out the average properties of some gas in a container, an expert weatherman might ponder about (or even calculate) the resulting fluid motions, but I don't want to go into such details: simple laws of thermodynamics are enough.
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