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Comments 64301 to 64350:
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CO2 lags temperature
jzk - Feedbacks act as a scaling on whatever forcing changes occur, which is why they are feedbacks. At the peak of an interglacial the climate is in (relative) equilibrium, no thermal inertial to wait for, the climate is not changing (important point). Then the Milankovitch forcing changes downward. If there were no feedbacks whatsoever, such a change in energy will of course cause the climate to cool. With feedbacks (water vapor, CO2 after 500-800 years, albedo changes, etc.) the climate will cool to a larger (positive feedbacks) or smaller (negative feedbacks) extent than the direct forcing change alone would cause. Feedbacks are a response to forcing, not an independent entity. If forcing changes, the feedbacks will as well - they will not (independently) hold the climate energy stationary, or they would instead be independent forcings. Over geological time frames feedbacks are very fast - amplifiers of forcing changes. If you are speaking into a microphone, and drop your voice to a whisper, would you really expect the amplifier to keep the output volume unchanged? Or would you instead expect the output volume to change as per your input volume change times the amplification? -
jzk at 01:47 AM on 10 February 2012CO2 lags temperature
CB @336, I don't refer to the "accumulated warming" or "inertia" of the temperature rise. However, all of those gasses that are present at peak temperature contribute to warming just by being there. It is not as if they are a "fuel" that burns out, they warm by trapping radiation. Does not that warming need be overcome by the downward Milankovitch forcing in order for other positive cooling feedbacks to kick in? Of course as temperature lowers, CO2 is absorbed, and that contributes to cooling. But first it must start its descent despite the presence of these warming gasses. Again, thanks for helping me with this, any citation to the peer reviewed studies would be much appreciated. -
Steve Case at 01:41 AM on 10 February 2012Global Sea Level Rise: Pothole To Speed Bump?
#60 KR at 16:09 Yes, I read you post. -
CBDunkerson at 01:07 AM on 10 February 2012CO2 lags temperature
jzk wrote: "However, before that can happen, the cooling effect to prevent the melt via the top end Milankovitch factors must overcome the very powerful warming effect that the high level of CO2 has." No, this is an inaccurate view of the situation. Cooling from the 'negative Milankovitch forcing' does not have to 'overcome' the total accumulated warming from the 'positive Milankovitch forcing' and all feedbacks before cooling sets in. The transition is 'immediate' save for a very short (geologically) lag time. Once the Milankovitch forcing passes the 'warming peak' there is then progressively less of a warming forcing, which results in progressively less atmospheric water vapor (and thus lower water vapor feedback), more ice formation, oceans cool and absorb more CO2, et cetera. There is no (long term) 'inertia' to overcome... when the sign of the forcing changes all the feedbacks do as well. -
Dave123 at 00:40 AM on 10 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
If you want to see Mike Mann working as a scientist drop over to this thread on Real Climate Volanos, Trees, Bark Especially note the exchanges in the comments. The contrast to WUWT couldn't be clearer. -
muoncounter at 00:38 AM on 10 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Read the book? That's too much to expect. Some folks don't even want Mann to be able to speak in public at his own university. Coal group raps Mann, seeks halt to lecture These groups attract the same people who scream about their 'liberty' and fear their 'freedom' will be taken away. -
Tom Curtis at 00:24 AM on 10 February 2012CO2 lags temperature
jzk @333, the short answer is that after the passing of the peak Milankovitch NH Summer warming, the Earth cools very slowly over several thousand years. Because cooler water absorbs more CO2 than warm water, that cooling gradually reduces the CO2 level in the atmosphere. Studies have shown that a Milankovitch Minimum NH summer warming will initiate a new glacial only if CO2 levels are at around 240 ppmv (+/- 40 ppmv). The large range is due to the fact that there are a range of studies giving partly overlaping results in that interval, and also because the level of CO2 that will stop the initiation of a glaciation depends critically on the strength of the Milankovitch Cycle. Historically, at least on glacial commenced when CO2 levels where at around 280 ppmv, but most initiate with levels around 240 ppmv, and Berger and Loutre show that even in a weak cycle, glaciation will initiate with CO2 levels around 210 ppmv. -
Paul D at 00:07 AM on 10 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I like Manns work and the thousands like him that contribute to our knowledge about AGW. But I don't have the attention span these days to read peoples 'life' stories. I did start reading it (like I started reading Hansens book) but got bored. I wish these scientists would spend time to write popular science books or work on TV documentaries that get the science across to millions of people, instead of this sort of thing. That would be far more productive than these types of books. -
jzk at 00:00 AM on 10 February 2012Medieval Warm Period was warmer
Tom @73, I have no problem drawing that conclusion from the Mann data, and of course I have noticed that. That is the kind of presentation that SkS should have. But picking a decade of our recent warmest data (+- 3 years) and comparing it to 300 years of previous data just so that one chart will be full of white and the other red does nothing other than to mislead people that don't actually look to see what is behind the chart. I use the word "mislead" as a description of the effect of the comparison, not the intent. I have no idea what the intent was. If the data are on your side of the initial premise anyway, why not just present it in the most fair way possible? -
Dikran Marsupial at 23:58 PM on 9 February 2012CO2 lags temperature
jzk The change in CO2 between glacial and interglacial conditions is only from 190 to 270 ppm, an as the fadiative forcing from CO2 only increases logarithmically it isn't necessarily "very strong" compared to the change in solar forcing due to Milankovic cycles. You would need to compute the numnbers to know whether your argument was valid, and I strongly suspect that the scientists did that before publishing their finings. Also the feedback from CO2 is self limiting in the sense that IIRC the outgassing of CO2 due to heating of the oceans is linear, so in the absence of external forcings it would rapidly (on geological timescales) reach a new equilibrium. Thus by the time Milankovic cyle went into a cooling phase CO2 would no longer be on the way up. -
jzk at 23:46 PM on 9 February 2012CO2 lags temperature
I am very interested in understanding how the Milankovich cycle at the top of the cycle reverses warming when the influence of CO2 is so strong and continuing to experience positive feedback (although perhaps diminishing). I understand that "Northern ice sheets melt less during summer and gradually grow over thousands of years. This increases the Earth's albedo which amplifies the cooling, spreading the ice sheets farther." However, before that can happen, the cooling effect to prevent the melt via the top end Milankovitch factors must overcome the very powerful warming effect that the high level of CO2 has. At this point, of course, CO2 is still rising and ought to be more powerful than any other time during the cycle. The Imbrie, et all papers don't deal with this that I can see. I realize that this issue isn't novel having been discussed on this forum before, but what peer reviewed authority engages this issue? Thanks!!! -
Bob Lacatena at 23:32 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Pirate and Dale, Your Wattsian views of the issue as a debate with sides, recruitment, demarcation lines, and most importantly "belief" all point to a perspective that this is all about personal choice. On the one hand, I'd tell either of you that your time would be much better spent reading something else that teaches you about the actual science. On the other had, given your rather chauvinistic-militaristic view of the issues, perhaps what you need is a better insight into the perspective of someone other than yourselves (like that of a scientist who is doing his job, coming up with data and analyses that other people don't like, and then being hounded and vilified for it). You two are exactly the sort of people who should read the book, but with an open mind and an eye towards learning something about how your fellow skeptics behave and the use of "tactics" as an approach to a field of science, rather than participation in the science itself. -
Bob Lacatena at 23:19 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
31, Bernard J. That's not at all a bad idea, and one that would be easily enforced. At a minimum, there should be a big icon next to a commenter's name showing who has or has not bought the book from Amazon. Comments should also be sorted in that order (people who bought it first, people who claim/pretend to have bought it second), and summarized that way ("Average rating for the people who bought the book from Amazon, 4.89, Average rating for all others, 1.32"). -
John Mason at 23:00 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
What is particularly interesting, in a behavioral way, is the swarming of the Amazon site. I'm still reading Mann's book, but the goings-on with all those negative reviews from people who must somehow be able to read dozens of pages a second (!!!) provide an absolutely classic example of the politics of the climate debate. Mann writes an account of it and a whole bunch of helpful dudes then come along to provide of working demonstration of what he describes! -
Dikran Marsupial at 22:29 PM on 9 February 2012Still Going Down the Up Escalator
RobertS (various posts) "Slope in a linear regression of either temperatures or GCM output, however, is still an unobservable parameter - it's not a measurable, identifiable feature of the data itself, but of your particular model - and cannot be verified" This is not true, as others have pointed out there the data has a unique linear least-squares fit, just as the difference between the temperature at the start point and end point is uniquely defined by the data (as I pointed out on Dr Brigg's blog). You can view linear regression as being a generative model of the data, however it also has a perfectly reasonable interpretation as a descriptive statistic. "but I believe Briggs overall point is that the frequentist interpretation of confidence intervals is not intuitive, which begets confusion." This is true, conidence intervals are counter-intuitive, however if that is Brigg's overall point he is making it rather indirectly, to say the least! "And that confidence/credible intervals of observables is preferable to confidence intervals of model parameters." This is non-sense, which is preferable depends on the purpose of the analysis. "I don't have a problem with a global mean surface temperature. The issue comes with how uncertainty in this value is calculated and viewed, and how a change in GMST is determined." Are your concerns answered then, by my analysis which shows that using Bayesian methods, the uncertainty in the estimates of GSMST have almost no effect on either the expected regression or the credible interval? You might want to ask yourself why Briggs hasn't already performed this analysis before making a fuss about it on his blog. BTW, not all statistics should be "predictive", they should be chosen to suit the purpose of the analysis. If you are aiming to predict something, then obviously predictive statistics are likely to be most appropriate. If the purpose is to describe the data, then descriptive statistics are appropriate, if you are exploring the data, then exploratory statistics. Ideally a statistician should have all of these tools in his/her toolbox and be able to chose the appropriate tool for the job at hand. -
dorlomin at 22:12 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I for one am dissapointed the spoilers are getting removed. Perhaps someone can get in touch with Mann and see if he can get Amazon to keep them up. They are pretty much evidence of the books argument. -
Dikran Marsupial at 22:09 PM on 9 February 2012Still Going Down the Up Escalator
Steve L The Bayesian analysis doesn't take autocorellation into acount (unlike Tamino I am no expert in time-series analysis - yet ;o). However the main aim was to determine whether the effect of the uncertainty of the estimates of GMST had much of an effect on the width of the credible interval. It doesn't which suggests that Dr Briggs is making a bit of a mountain out of a molehill (if not a worm cast), in my opinion. BTW, if you are interested in Bayesian statistics then a good place to start is Jim Alberts book "Bayesian Computation with R", which as a package for the R programming environment called "LearnBayes" that implements Bayesian linear regression (which I used to generate the plots). -
John Russell at 22:03 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I've just checked and can report that Amazon appears to have removed the short, 1-star, deliberate 'spoilers'. Actually the reviews now left seem to illustrate well the polarity of the discussion and, if anything, will encourage the casual viewer to read the book. So shall we call this 'bookgate'? -
dorlomin at 21:56 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Other than Craig Loehle, none of those opposed to Mann have done their own reconstructions. This one of the salient points, they dont have a credible alternative to offer. -
Sascha Tavere at 21:43 PM on 9 February 2012Global Sea Level Rise: Pothole To Speed Bump?
Skywatcher/KR Understood ... collaps means exactly that. Nothing gently timeconsumig about it. (I got waylaid by language, like: economic collapse) Thank you for clearinng the head. It isn't a story easily told to Monckton enthousiasts though (there are still a few left). -
owl905 at 20:52 PM on 9 February 2012Volcanic Influence on the Little Ice Age
@Klaus 20 - Scaddenp quotes the best reconstruction. Add to that a Swedish study that highlights the disjoint between past northern and southern hemisphere trends. http://www.physorg.com/news/2011-10-simultaneous-northern-southern-hemispheres-result.html It's noteworthy for the current warming that the effect is ubiquitous. That's very different from the reconstructions that show both regional and hemisphere differences driven by natural variations. -
Bernard J. at 20:41 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
The denialist carpet bombing shows a serious flaw in Amaon's comment system. It is being hijacked for political purposes - something about which the Amazon management should be excedingly concerned. Frankly, reviews for topical material books such as this one is should only be accepted from people who have purchased it from Amazon. Similarly, comments should only be accepted from folk who have a minimum purchase history with Amazon. It's not only in Amazon's interests as an ethical trader, but as a successful one, that they weed out politically-motivated nonsense. -
Tom Curtis at 20:07 PM on 9 February 2012Still Going Down the Up Escalator
RobertS, the data of the temperature series is a set of pairs of numbers. The linear regression of such a set has a unique solution. Therefore it is a property of that set of numbers. So, to answer the question, it is a property of the data set, not of our mathematical manipulation. We could employ the same form of verbal tricks you do in making your case with regard to measurements. Consider a simple mercury thermometer placed in a pot of water. The length of the mercury column in the evacuated tube depends critically on the diameter of that tube. Does that make the temperature a property of the evacuated tube, of the the manipulation of glass in creating the tube? By your logic we must conclude it is a property of the glass blowers manipulation. Perhaps that is to simple for you. Suppose instead of a mercury thermometer we measure temperature with an IR thermometer. The IR thermometer records the intensity of IR radiation across a range of frequencies. Using the laws of black body radiation, a computer chip then calculates the temperature of the body emitting the radiation. So, is the temperature a property of the pot of water, or the mathematical manipulation that derived the temperature from the IR radiation. For consistency, you need to say the later. But then you are committed to the claim that Planck's law has a temperature of x degrees, where x is the result of the measurement. Going back to your example, the formula for the linear regression of a time series does not have a slope of 0.175 C/decade (+/- 0.012°C/decade). Neither does the computer, or the pages of paper on which the calculation was performed. That slope is the property of the NCDC temperature data. In other words, it is simply incoherent to say the linear regression is a property of the mathematical manipulation rather than the data. It is absurd on the same level as saying "The green dreams slept furiously together". And the reason you are generating such incoherent notions is because you are trying to reify a purely pragmatic distinction. The question you need to be asking is not whether the linear regression is a property of the data set or the mathematical manipulation (trivially it is a property of the data set). What you need to ask is, is it a useful property to know. And, as with any question of usefulness, that depends critically on the use intended. -
RobertS at 19:14 PM on 9 February 2012Still Going Down the Up Escalator
Tom @125 "I don't know if that is Briggs main point..." It's probably not his main point - I misspoke. He's primarily arguing for the use of predictive statistics, which is not standard in most fields. And because frequentist interpretations are counterintuitive and often unrealistic, he prefers Bayesian predictive techniques. Eli @129, I don't have a problem with a global mean surface temperature. The issue comes with how uncertainty in this value is calculated and viewed, and how a change in GMST is determined. -
EliRabett at 18:48 PM on 9 February 2012Still Going Down the Up Escalator
Robert S is simply Essex and McKitrick dresses in fancy statistical pants. http://www.realclimate.org/wiki/index.php?title=C._Essex_and_R._McKitrick Been there, done thatModerator Response: [Dikran Marsupial] Link activated -
Bern at 18:47 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I should clarify: I meant "actual contents", as opposed to "imagined contents" - a couple of reviews seemed to be based on the latter. Oddly enough, the reviews I rated unhelpful were all 1-star, and those I rated helpful were all 5-star. Hmm... coincidence? -
Bern at 18:46 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I had a look at the Amazon reviews, and rated them as to how helpful I thought they were. The ones that didn't actually describe the content of the book, but were full of vitriol (some of which constituted little more than a couple of insults), were rated as 'unhelpful', while the ones that described & commented on the actual contents of the book were rated as 'helpful'. -
RobertS at 18:22 PM on 9 February 2012Still Going Down the Up Escalator
Tom Curtis @125,126 You're being silly now. Practically, and perhaps physically, we could never measure temperature perfectly. So we can never truly observe "temperature" You're right. From a statistics standpoint, however, the distinction is different. Let's say we have these devices which we'll call "thermometers" that measure, for the sake of simplicity, some quantity called "temperature" (though we both agreed that they don't actually measure temperature). Say we want to measure the temperature of the entire planet. It would be simply unfeasible - or even impossible in practice - to measure every single point on the entire planet, so we place a few of these devices at choice points around the planet, and with the magic of statistics, from these measurements we construct an "average" and an "uncertainty" using some or other method. This "average temperature" isn't an actual temperature which we've measured and neither is the uncertainty; they arise from the method in which we combined our sample. Is our method the true and correct method? Probably not, but we can't say that with absolute certainty. Whether it's a reasonable method is another question. Say we then compute these average temperatures in regular time intervals to find an "average monthly temperature", and we want to see what these average monthly temperatures are doing over some specified time period. So we look up some kind of statistical model, compute it for our average monthly temperatures, and out pops some parameter of that model which we'll call "slope". Is slope a feature of the data itself, or the way in which we manipulated the data to create our model? Is our model the true and correct model? Probably not, but we can't say that with absolute certainty. KR @127 "However: Are you asserting that a trend line cannot be determined (as a statistical evaluation, within stated and computed limits of uncertainty) from the data?" No, of course a trend line can be determined from the data. I might question the value or interpretation of such a metric, but not that one can be calculated. For what it's worth, it's clear that Tamino knows his stats, and he has that rare quality of being able to explain esoteric statistical methods easily to laymen, but his latest post again misses Briggs' point. -
Still Going Down the Up Escalator
RobertS - Fair enough, I have perhaps not been sufficiently clear on the terminology. However: Are you asserting that a trend line cannot be determined (as a statistical evaluation, within stated and computed limits of uncertainty) from the data? I ask because that is the apparent direction of your recent comments. And if this is not what you are asserting - then what is your issue with such statistical analyses? Quite frankly, I'm finding difficult to ascertain your point... -
Phila at 17:12 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Pirate: "Ultimately, any reviews of books on AGW (whether from the skeptic viewpoint or the believer viewpoint) are going to be heavily biased." Oh, absolutely. Some reviewers will say that the peer-reviewed consensus science is very likely to be correct, and that it mandates an intelligent response from reasonable people. And others will say that Michael Mann is a lying communist stooge who was sent by George Soros to destroy capitalism, depopulate the world by 80 percent and leave a handful of cave-dwelling survivors to gnaw twigs by the light of phosphorescent lichen. So yeah, these views are equally biased and we can write 'em both off. That's just common sense, right? -
Phila at 17:04 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Dale, But since the book looks to be more about Mann's sob story than any real science, I wouldn't have read it regardless. So you don't know what the book is actually like, and you're not at all interested in finding out. Very illuminating. Thanks for sharing. -
Tom Curtis at 16:55 PM on 9 February 2012Still Going Down the Up Escalator
RobertS @124, tell me the last time you saw a temperature. Indeed, we cannot even detect temperatures with our sense of touch. What we detect is the rate of heat transfer through the skin, and that in non-quantifiable terms. -
Tom Curtis at 16:52 PM on 9 February 2012Still Going Down the Up Escalator
RobertS @121:"I believe Briggs overall point is that the frequentist interpretation of confidence intervals is not intuitive, which begets confusion.
I don't know if that is Briggs main point, but if it is, well yes (obviously), but they do not introduce anywhere near the confusion Briggs has with his comments. And speaking of which:"And that confidence/credible intervals of observables is preferable to confidence intervals of model parameters.
The distinction being made here is arbitrary, and without any justification in epistemology. As Briggs (and you) are using the distinction, the temperature at a specific time and location is an observable, but the GMST (Briggs) and the linear regression of the GMST over a period (you) are not. However, respectively, the GMST is determinable by an (in principle) simple calculation. It is rendered difficult not by any fundamental issue, but by limitations in the available observational data set. And once you have a time series of the GMST, determining the linear trend is an even simpler calculation with no in principle difficulties. Your distinction appears to be, therefore, a distinction between data obtained by "direct" observation, and data derived by mathematical manipulation of data obtained by direct observation. But as has been noted previously, there are no direct observations of temperature. Rather, we directly observe the length of a column of mercury or alcohol. Or we directly observed the degree of bending of a bi-metal strip. Or we directly observe the current in a circuit (by observing the position of a needle). Converting any of these "direct" observations into temperature data involves calculations just as much as determining the linear regression of a time series. At the most fundamental level, all that is actually observed (visually) is progression of patterns in colours on a two dimensional field. If you are going to make a distinction between observing temperatures, and observing slopes, there is no in principle distinction that will keep you from limiting "direct observation" to that simple descriptions of that visual field (and good luck developing any physics on that basis). In practice we do not make the distinction between what we observe, and what we can know from what we observe except pragmatically (and because pragmatically, based on the needs of particular situations). Briggs appears not to recognize that, and wishes to reify a pragmatic distinction. To which the only appropriate response is, more fool him. -
RobertS at 16:48 PM on 9 February 2012Still Going Down the Up Escalator
KR @122 Model parameters like slope are, by definition, unobservable. That is, they cannot be measured, observed, detected, identified, and thus, verified in the real world. -
RobertS at 16:34 PM on 9 February 2012Still Going Down the Up Escalator
In case you haven't seen, Briggs had previously attempted to quantify the credible interval on the observables for the BEST record here, with the result being greatly increased uncertainty in temperature estimates. -
Still Going Down the Up Escalator
RobertS - "Slope in a linear regression of either temperatures or GCM output, however, is still an unobservable parameter" What, in the vast world, are you talking about? That's complete nonsense. Slopes are a completely observable quantifiable (including uncertainties) value (see Tamino on this very topic). you're sounding as bad as Rumsfeld with his "unknown unknowns"... Spatial correlations of temperatures ("a place on the Earth where we haven't sampled") are extremely well established (Hansen et al 1987), and Briggs is simply arguing semantics, not numbers. You have most certainly not presented evidence to the contrary. I look forward to Brigg's further posts. Although, based upon what I've read so far, I don't expect anything beyond a confirmation of his biases, poorly supported excuses, and misinterpretations... -
Global Sea Level Rise: Pothole To Speed Bump?
skywatcher - Agreed; Greenland is a prime candidate for steady increases in ice loss/sea level rise, while Antarctica is a risk for jumps in sea level due to grounded glaciers cutting loose. Either way, folks (are you listening, Steve Case?) rises on the order of 1mm/day are entirely possible, given that warming is something like an order of magnitude faster than anything in the paleo record. And hence, so are the possibilities of sea rise rates. Personally, I'm not encouraging coastal real estate investments for anyone I know... -
RobertS at 16:02 PM on 9 February 2012Still Going Down the Up Escalator
Muoncounter @107 "In this case there are physical models and they predict a slope that is verified by the observables." When I say "slope", I mean the b quantity in a simple linear regression model y=a+b*x+e. If you want to argue that climate models skillfully predict actual temperature - something your source doesn't attempt to show - or that the slope in a linear regression of temperatures is insignificantly different from that of climate models, that is one thing (exactly what the latter means I can't say for certain). Slope in a linear regression of either temperatures or GCM output, however, is still an unobservable parameter - it's not a measurable, identifiable feature of the data itself, but of your particular model - and cannot be verified. Unobserved observables are quantities which can be measured, but haven't been. So that could be the temperature measured at a particular station some time in the future, or simply a place on the Earth where we haven't sampled. Tom Curtis @108 I agree that a "classical predictive interval" would be similarly wide as a Bayesian interval, and Dikran has indeed shown the credible interval of the regression to be comparable to the classical interval, but I believe Briggs overall point is that the frequentist interpretation of confidence intervals is not intuitive, which begets confusion. And that confidence/credible intervals of observables is preferable to confidence intervals of model parameters. Briggs is part-way through a new series of posts about time series analysis, model selection, and how to treat uncertainty. Maybe it will help clear up some confusion about his position. -
skywatcher at 15:27 PM on 9 February 2012Global Sea Level Rise: Pothole To Speed Bump?
#58: West Antarctica is buttressed by two great ice shelves, the Ross and the Ronne-Filchner. As we have already seen on the Antarctic Peninsula, ice shelves can spectacularly collapse in very short spaces of time, leading to great armadas of icebergs (Larsen A & B, Wilkins - video). If the main ice shelves go, sea levels will suddenly rise much more quickly as the grounded glaciers that are buttressed by the ice shelves accelerate. An interesting paper on a past example driven by warming seas. Ultimately, gradual acceleration is most likely with Greenland (and is observed), while West Antarctica has the potential for more sudden acceleration, but isn't presently losing mass so fast. -
Tom Smerling at 15:12 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Thanks for writing this, John. Mike M. is a true science hero, and deserves support. -
muoncounter at 15:09 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
pirate#18: "Books of this nature are not going to sway the other side, but may recruit lukewarmers." Consider these January 2012 US poll results: A new Rasmussen Reports national telephone survey of Likely Voters finds that 64% say global warming is at least a somewhat serious problem, including 30% who say it’s Very Serious. That suggests that 34% are in the 'somewhat serious' camp; you might call them 'lukewarmers.' If that large a population might be reached by Mann's book, it is very worthwhile effort. It is also a worthwhile effort to publicize the vile tactics in use by the deniers. "nothing on this issue will be resolved by any amount of posts here. It is an exercise in futility." I am sure there are quite a few folks who have learned a lot from posts here. Is education an exercise in futility? If so, why are you a teacher? -
caerbannog at 14:57 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Just wanted to post another reminder to those folks who will be in Southern California next week -- Dr. Mann will be speaking at the Aquarium of the Pacific in Long Beach (in the greater LA area) on Feb 15. Details here General public admission is only five US bucks. That means that you will have plenty of money left over to buy a copy of "The Hockey Stick and the Climate Wars" for Dr. Mann to sign. Just think of it -- your very own signed copy of "The Hockey Stick and the Climate Wars".... occupying prime real-estate on your coffee table, just waiting for your favorite denier in-law to see it. Then when your denier relative starts ranting about Mann's "hockey-stick fraud", you can open the book and say to him, "Look at this: It's even signed by the author." Then grab a bag of popcorn and watch the show!Response: [JC] converted your URL into a hyperlink, it was stretching out my web design. -
pbjamm at 14:55 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
apiratelooksat50@18 "Ultimately, any reviews of books on AGW (whether from the skeptic viewpoint or the believer viewpoint) are going to be heavily biased." Belief is not required when evidence exists. True Skeptics draw their conclusions from available evidence. True Believers dont require facts to base their beliefs on. in other news... I wish I had time to read the book before I go and see him speak at the Long Beach (California) Aquarium next Wednesday. Any other locals planning to attend? -
Tom Curtis at 14:48 PM on 9 February 2012Skepticism About Lower Atmosphere Temperature Data
Fred Staples @30, are you suggesting that the Hadley Center did not use the data in constructing the graph? Regardless you are using a very simplistic analysis. By eye, the weighting function above 10 Km of the TMT channel represents approximately one quarter of the channel weight. I will use 0.2 to be conservative. From 1979-2002 the positive trend over the altitude range of 0-10 Km has been 0.1 C per decade according to HADAT. Over the same period, the average over the range 10-20 Km has been around -0.5 C per decade. The effect is then that over the whole channel the trend is (-0.5 x 0.2) + (0.1 x 0.8) = -0.1 + 0.08 = -0.02. These figures are of course very inexact. They merely serve to show that looking solely at the relative area of the weighting function to determine the effect on the trend is a gross distortion. It may require 22 years to find statistically significant cooling at 15.75 Kms, but it is still a cooling trend, and a larger cooling trend than the warming trend in the troposphere. Therefore it significantly distorts the TMT channel as a measure of tropospheric temperature trends. Pretending otherwise is nothing but wishful thinking. -
scaddenp at 14:41 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
"In the end, nothing on this issue will be resolved by any amount of posts here. It is an exercise in futility. Energies could be better focused elsewhere. " If "by this issue" you mean "is the book any good?", then I agree. If you mean "is our theory of climate valid", then posts here help those who want to find out what the science says. It wont help those who have made up there minds on an issue from ideological or other biases that are immune to data. -
Daniel J. Andrews at 14:37 PM on 9 February 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
Glad there's a Kindle version. I'll be able to read it while away. John, I did find your review helpful so indicated that on Amazon after I bought the book. -
Sascha Tavere at 14:22 PM on 9 February 2012Global Sea Level Rise: Pothole To Speed Bump?
Skywatcher #55, thanks Mean annual rate of ice mass loss Greenland: 200-300 Gt Mean annual rate of ice mass loss Antarctica: 70-210 Gt Permafrost warming: 0.5°C to 2° Freshening of part of the Arctic Ocean: 2006–08 increase 8400 ± 2000 km3 http://www.aoml.noaa.gov/phod/docs/Goni_etal_2011.pdf I am prepared to worry about either or both but I still don't quite see why Antarctica should be favoured eventhough the WAIS is indeed perhaps more prone to melt at its base. Is there evidence (yet)? In favour of "Artic worries" might be the the permafrost melt run-offs draining into Arctic waters. Am I being obtuse? -
KBow at 14:16 PM on 9 February 2012Debunking Economic Myths from the Climate Hearing
Working link. Comparing the Cost -
KBow at 14:14 PM on 9 February 2012Debunking Economic Myths from the Climate Hearing
This is the best place I found for this. In the Resources>climate graphics http://www.skepticalscience.com/graphics.php?g=11 the link to Watkiss et al (2005) link does not work on the graphics page. It does work on the graph on this page. Please delete this.Response:[DB] The correct link is:
http://ec.europa.eu/clima/policies/package/docs/final_report2_en.pdf
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Steve L at 14:11 PM on 9 February 2012Still Going Down the Up Escalator
Hi Dikran Marsupial -- does your Bayesian analysis correct for autocorrelation? What you've done is really cool, and is something I should learn how to do! But I wonder if autocorrelation in the series would widen your credible interval.
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