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Tristan at 03:58 AM on 1 October 2011Understanding climate denial
cRR: The ability to change your stance like that is the essence of skepticism. Above all, we must remain skeptical of ourselves :) Stephen: You're right. The anti-CAGW/right-wing blogosphere is not representative of typical 'denialism'. In reality most people on both sides aren't well informed and will tend to the default position of whichever political team they're on. This puts undue influence in the hands of political leaders. The politics should be about addressing the problem, not assessing whether there is one (I thought we'd set up an independent international body to do that). The point you made about being non-threatening is very important. Derision and accusations incline people to commit further to their opposing view, rather than relax and listen to yours. -
angliss at 03:47 AM on 1 October 2011Pielke Sr. and SkS Disagreements and Open Questions
One quick comment (still digesting this) - SkS and Pielke Sr may be talking past each other on the CO2 thing. I suspect he's thinking of CO2 vs. water vapor, while you're not. -
Bob Lacatena at 03:43 AM on 1 October 20112011 Sea Ice Minimum
40, Tom, 43, Dikran, I believe, however, that the "lower angle of incidence" theory presumes that incoming sunlight is a major factor in local warming/melt. I thought that it's been determined that the water temperature and not the sunlight itself was the main factor. Admittedly, the increase in local warming due to more exposed water due to more ice melt will still be lower (due to the lower angle of incidence), but if the main temperature of the water comes from heat being transported in from outside of the Arctic, then I would think that would low angle of incidence would be a minor factor. The bigger factor, in the end (I believe) will be flat out warmer water temperatures. Ten years from now, with the water that much warmer, everything will melt faster and more thoroughly, from start to finish. Eventually it will be so warm that it just overwhelms whatever ice is there. For that reason, I think that the end will come surprisingly quickly. [On the flip side, I do think the complete disappearance of the sun, dropping air temperatures to the point where things start to refreeze, is a major factor, and the fact is that the melt season is much shorter at the actual pole, so it may be a long time before the seas are warm enough to melt everything there before the sun sets.] -
John Russell at 03:41 AM on 1 October 2011Understanding climate denial
One thing we've not considered is the role of the sociopath in spreading denial. People with sociopathic tendencies apparently make up 4% of the population. I can't help think sometimes that some of the most vociferous of those in climate change denial would come out very clearly in this questionnaire as sociopaths. I'd mention one famous touring 'sceptic' by name but I guess he'd threaten to sue me. And if that doesn't give you a clue to whom I refer, I don't know what would! -
muoncounter at 03:40 AM on 1 October 2011Modern scientists, following in Galileo’s footsteps
John R#40: "Being persecuted does not make you right," Let's not give those in denial a pass on that. Persecution? Really? Giordano Bruno was persecuted. Having to publish a paper (of dubious value) in a minor journal rather than in Nature doesn't come close. "any more than agreeing with the majority somehow makes you wrong." And yet you often hear that on the denial blogs. To agree with the majority position is said to have 'drunk the Kool-aid' or to be somehow incapable of independent thought. As if it is impossible to independently review the evidence and conclude that the majority opinion is correct. Example: The FT is drinking climate KoolAid -- by none other than our friend RPJr. -
Modern scientists, following in Galileo’s footsteps
To be the "next Galileo", it is not sufficient that you be a maverick, that your theories are contradictory to the consensus, that you are laughed at. You must also be correct. That's a rather higher standard. -
OA not OK part 20: SUMMARY 2/2
My apologies, Bernard J. - in my previous post I was mistakenly responding to the "acidification" portion, not the (quite correct) variation of neutral point. More caffeine needed, I believe... -
Bernard J. at 03:01 AM on 1 October 20112011 Sea Ice Minimum
"Whether or not melting ice follows a Gomperts path, I suspect that it will follow one of the asymmetric sigmoids..."
...for the sort of reason that Dikran Marsupial mentions in the first paragraph of #38. -
OA not OK part 20: SUMMARY 2/2
The last time I ran into the semantic issues with "acidification", I simply noted that: If you stand at the South Pole, then walk 100 meters in any direction, you are still in the Southern hemisphere. But, you have indisputably moved 'northward'. And 'acidification' is the term used for a chemical mixture moving towards acidity. -
Bernard J. at 02:55 AM on 1 October 20112011 Sea Ice Minimum
Logistic curves are nice and easy, but they're symmetrical about the point of inflection, which is often quite an artifical assumption about natural processes. Of course, this is not to say that the shape of a Gompertz is not itself an artifical fit to certain sets of data (usually it is), but in various ecological contexts at least I've found Gompertz nearly always seems to better describe the nature of trajectories than do logistics, von B's, or other of the stable of sigmoids. Whether or not melting ice follows a Gomperts path, I suspect that it will follow one of the asymmetric sigmoids... -
Tom Curtis at 02:54 AM on 1 October 2011Modern scientists, following in Galileo’s footsteps
Tom Smerling @38, while I cannot speak for Einstein or Hawking, it is absolutely true that Galileo invented modern science with his detailed observations of bodies in motion. That, far more than his astronomical observations and writings marked a break with past practice and dependence on authority rather than observation as arbiter of knowledge. -
John Russell at 02:45 AM on 1 October 2011Modern scientists, following in Galileo’s footsteps
Tom, les, The 'Galileo was persecuted, but right' meme should be paired with the 'just because it's the consensus doesn't make it correct' meme. They both spring from the same cherry-picking of history and both are very popular with those in denial. Being persecuted does not make you right, any more than agreeing with the majority somehow makes you wrong. And, by definition, once you've been proved right and everyone suddenly agrees with you, you're in the consensus; and then it's those that don't agree with the new consensus that suddenly become the mavericks. What makes someone either a 'Galileo' or a part of the consensus, is just where you choose to draw a line for the start and end dates. The arbitrary nature of which shows up exactly why these memes are so utterly flawed! Galileo was Galileo and trying to make serious comparisons in support of any take on climate science is just plain bonkers. -
Philippe Chantreau at 02:41 AM on 1 October 2011Modern scientists, following in Galileo’s footsteps
Tom makes an excellent point. Someone, maverick or not, may very well be right about a subject and at odd with accepted ideas on that subject. However, it takes more than the correct insight to convince others, it takes sufficient evidence. Science is not a game of "I told you so 20 years ago." If the evidence supports accepted ideas better than new ones, they will remain in place until more evidence is acquired. It is possible that some true skeptics are right about the role of CO2 in climate, but they have so far furnished no evidence near sufficient enough to overturn the current, painstakingly acquired model of Earth climate. -
Dikran Marsupial at 02:38 AM on 1 October 20112011 Sea Ice Minimum
Tom Curtis Thanks for that, being wrong is always an effective way of learning! The models in the Stroeve et al. paper (thanks muon) have a sigmoidal shape, which is strong support for that kind of model. -
Tom Curtis at 02:36 AM on 1 October 20112011 Sea Ice Minimum
No shame for an out of work philosopher to be scooped by Bob Grumbine on Arctic ice. -
Stephen Baines at 02:35 AM on 1 October 2011Understanding climate denial
Tristan, I agree that it will be hard to turn any of the big names. Afterall, it is their uniquely active intransigence that has made them "big names" in the first place and which has put them in the position where reversal will lead to public humiliation. If they hadn't sold themselves down the river intellectually, they would have been convinced by the evidence years ago. But for the same reason I think we should be careful not to paint too broad a canvass from their unusual example. That way leads to nihilism. In my experience, many people who "deny" climate change do so on a much more passive/indirect basis. (Note, I do not consider people who post on internet blogs a random sample of these people!) They are either going along with others they relate too, against others they don't relate to, or they are challenged by the idea that the effect of humans could compare to the power of nature. With all the noise surrounding communication about climate science, those indirect associations take over. But I do not believe they are not as committed personally to that position as the public faces of denial. They will listen to evidence when presented by a non-threatening source. In every major environmental debate on which the science spoke clearly, the science has won in the end, despite enormous efforts to derail it. That is not a call to complacency - it took effort. But you have to think that most people can be convinced by the evidence, else we might as well just give up and colonize Mars. -
muoncounter at 02:33 AM on 1 October 20112011 Sea Ice Minimum
Tom C: Bob Grumbine scooped you with a logistic curve fit: By my estimation method, there's about a 50% chance (54%) that 2035 or some year before that will show zero ice extent for September. It's only 6% that we'd see zero ice in 2029 (or before). And rises to 96% that we'll see zero ice (for the month) in 2042 or before. The 'or before' is important. Similar shaped graphics from model runs in Stroeve et al 2007, although the earliest ice free point in that paper was 2050. -
Tom Curtis at 02:16 AM on 1 October 20112011 Sea Ice Minimum
Dikran @38, as the sea ice area decreases, its limit comes closer to the pole. Consequently the angle of the incoming sunlight to the horizon decreases, and less energy per square meter is recieved. Hence a lower ice albedo feedback. As the minimum sea ice extent is in September when the sun is already low, that may well be enough to justify a Gompertz model. Not that I would in anyway dispute Larry Hamilton's final sentence. -
Bernard J. at 02:10 AM on 1 October 20112011 Sea Ice Minimum
TomCurtis. Dang. You just took the wind from my sails. Being an ecologist and all, Gompertz is one of my favourite sigmoids. I was about to plug the data in, and whaddaya know, I refresh and discover that you've pipped me! Pretty cool trajectory though... -
Dikran Marsupial at 02:05 AM on 1 October 20112011 Sea Ice Minimum
Tom Curtis, the Gompertz model, that takes me back a bit! Is there any reason to assume that the ice loss will slow as it reaches zero rather than speed up? I would have thought that it would continue accelerating due to the albedo feedback thing. It would be nice to use a method that handles the fact you can't have a negative extent properly (in the credible/confidence interval as well as in the projection). It might be a nice application for Beta regression (where the Gaussian noise assumption is replaced with a Beta distribution with the lower limit at zero and the upper limit learned from the data (or set to the surface area of the globe). Shame the GPML toolbox doesn't support it (yet). -
cRR Kampen at 02:05 AM on 1 October 2011Understanding climate denial
Very well, Tristan, I will confess. I was certain of GW by the year 1989. And until 2004 I thought it had to be the sun. In the end I got convinced by the facts I'm pushing forward nowadays like someone who quit smoking attacks everything and all in sight to with tobacco :) What have I gained? Actually some insight into denialism, particularly AGW-denialism. But a look over this thread will give same insight :) -
Bernard J. at 02:04 AM on 1 October 2011OA not OK part 20: SUMMARY 2/2
Harking back to Part 4 of the series, it's instructive, if apparently semantic, to note that pH 7 is not actually often the point of "neutrality", in terms of hydronium and OH- equivalence. Further, the pH of "neutrality" is temperature-dependent, and in the 'real world' it can wander half a pH unit or more from 7. As I said, it's largely semantic, but when arguing with acidification deniers it can be quite pertinent... -
Dikran Marsupial at 02:00 AM on 1 October 20112011 Sea Ice Minimum
dana1981 ;o) Do feel free to include the 2010-2012 predictions, the model assumptions are not too unreasonable for short term predictions, but do also include the ones from #34 to show how sensitive projections can be to the assumptions on which they are based, which is a useful lesson. -
Tom Smerling at 01:56 AM on 1 October 2011Modern scientists, following in Galileo’s footsteps
#34 John Russell -- Your point about mavericks is well taken. I wish we could quantify it somehow. E.g. Even for a short time period estimate the percentage of maverick ideas that are proven right, vs. those that end up in the dust bin. No doubt, it's tiny. However, I'm not sure there's a way to fit that argument fits in this particular rebuttal. The main point is not that the majority is usually right. In fact, climate is an example where some early mavericks were, in fact, proven largely correct. I think it is worth pointing out that mavericks proven right is a rare exception, though it gets complicate to try to shoehorn that into this particular rebuttal. But the larger point is not "are mavericks usually wrong, or right?" but "what is the basis of, and merit to, their position?" What do they bring to the table? Are they bringing fresh data, a new discovery, observation, new or analysis that withstands scrutiny? Or are they just coming with cherry-picked data and rhetorical ploys to try to sway opinion? As Weart stresses, the scientific establishment was correct in rejecting Arrenhius and Callendar, not because they are mavericks, but because their evidence just wasn't strong enough...yet. #37 les There are indeed different views about Galileo's contribution. Certainly his defiant, a bit in-your-face style -- not just his view of Copernicanism -- provoked the Pope, and it the dramatic trial elevated him to mythic status. And you're right that modern science -- increasingly a collaborative, rather than individualistic enterprise -- is far closer to the quiet, methodical style of Kepler et al than the "Hero Scientist" myth. However, few science historians -- even those who adamantly reject the hero myth -- would go so far as to dismiss Galileo as nothing more than a "fine instrument maker with a great imagination for measurement." His proto-scientific methodology, while not wholly unique, was a clear break with the traditional reference to classical texts. Who knows. Perhaps I've succumbed to the "Biographer's Syndrome" of overly identifying with their subjects. But I suspect that Galileo's methodology -- more than his semi-martyrdom -- is what prompted A. Einstein to dub Galileo "the father of modern physics—indeed of modern science altogether," and Stephen Hawking to state, "Galileo, perhaps more than any other single person, was responsible for the birth of modern science." -
NewYorkJ at 01:55 AM on 1 October 2011Climate Change Could be Expensive for Canada
Jonathan, The report cites this peer-reviewed study, which shows negligible change in winter mortality in 3 Canadian cities assessed. On "reduced energy demand", note that the report also doesn't quantify increased energy demand due to increased use of air conditioning, so it's quite a stretch to classify that shortcoming as one-sided. I haven't read the whole report and can't comment on the other potential benefits you mention. It's always preferrable, in my view, for these sorts of studies to be published in peer-reviewed journals, as that process can tighten them up. Mainstream economic studies (example: U.S. EPA, DoE) tend to not include in assessment of benefits reduced climate change and pollution, and reduced military costs. I wouldn't conclude that economists look "foolish", although I'll note that such studies often get cited as evidence of a net negative economic impact. -
Albatross at 01:53 AM on 1 October 2011Climate Change Could be Expensive for Canada
Jonathon @2, "Overall, the report focused almost exclusively on the cons, while omitting the pros." You are missing some key points. This report forms part of an ongoing "Climate Prosperity series" series, each report deals with specifc aspects of AGW and how it will likely affect Canada. So the report featured here has to be viewed in context. The report under discussion here was written because: "Little attention had been paid to the costs of inaction on global climate change and what this could mean to Canada economically as greenhouse gas emissions rise and climate change plays out. No nationally-focused economic study existed, until now. We found that climate change has a real and growing price tag to Canada and it could be expensive." Earlier this year NRT produced a report titled "Degrees of Change: Climate Warming and the Stakes for Canada". The purpose of that report was to document, "how Canada will be affected in a climate-changing world. The earth is warming and Canada is already experiencing this change at an even faster rate than other nations. Climate change promises to be both pervasive and pernicious. What will it mean to Canada? How will it impact us? What can we expect?" In that report more focus was placed on the pros and opportunities. The NRT has looked at this very closely and at the end of the day the pros are probably going to outweigh the cons, and adaptation and mitigation will be costly, and doing nothing will cost us even more. One of their primary conclusions is that: "The highest costs result from a refusal to acknowledge these costs and adjust through adaptation." -
Eric (skeptic) at 01:51 AM on 1 October 2011Are you a genuine skeptic or a climate denier?
Tom, when you have a chance, please address my paleo argument in that thread My contention is that the quantified sensitivity estimates rest solely on models, there is no other way to convert the large paleo temperature change to the smaller one for the doubling of CO2. I agree with your economic assessment, that it is a huge task. Rather than carbon offset purchases I would favor a tax and rebate like that proposed by Hansen to include a CO2-based tariff on imports. It makes it rather easy to step on the brake lightly to see unpredictable economic impacts and make adjustments. One thing you have left out of your analogy is technological progress that makes it easier to brake. That is being funded and studied currently using biology, technology, genetic engineering, etc. Combined with a long timeline, this will be a viable solution, but obviously that requires essentially the same degree of non-denial that you are looking for. -
dana1981 at 01:51 AM on 1 October 20112011 Sea Ice Minimum
Dikran, I can include your 2010 and 2011 predictions from #25 in the soon-to-be published 'lessons' post on Arctic sea ice, if you'd like :-) -
Tom Curtis at 01:42 AM on 1 October 20112011 Sea Ice Minimum
Seeing we're showing pretty pictures, I'ld like to add this one to the photo album:The graph is by Larry Hamilton, who explains it thus:
"It's just curve-fitting, but with a slight difference. Others tend to use linear, quadratic, exponential or logistic curves. Quadratics actually rise in the early years, then later crash below zero. Logistics have the more plausible property of approaching zero at a slowing rate, but the deceleration and acceleration phases must have the same rate. What this graph shows is a Gompertz curve, still relatively simple but yielding an assymetrical S. It looks similar to a quadratic but the differences are improvements: no rise in the early years, no crash below zero. The Gompertz predicts a slightly lower value than the quadratic for 2011: 4.4 instead of 4.6. It crosses the 1.0 line a few years sooner, but after that approaches 0 asymptotically. NOT that such curve fitting is more than a what-if exercise!"
Graph and quote from Neven's blog. With the gompertz model, it should be noted that once the average sea ice extent falls below about 0.5 million km^2, the Arctic will be ice free on some summers (but not all) due to variations in weather, so on this estimate the first zero ice minimum should be around 2030 even though there will be minimums with above zero ice for several years, even a few decades later. -
Tristan at 01:28 AM on 1 October 2011Understanding climate denial
Given this, It's going to be pretty hard to 'turn' any of the big names in the CAGW rejecting community. Just think how hard it'd be for them to 'turn' you! You might argue that logic/science is on your side (note: that's what they think too) so it's not a fair comparison but that's actually almost irrelevant. Cognitive dissonance alone isn't weighty enough to counteract all the other forces at play. -
Tom Curtis at 01:22 AM on 1 October 2011Are you a genuine skeptic or a climate denier?
Eric (skeptic) @486, the estimate of climate sensitivity is largely independent of the estimate of its individual components. This is partly because, in models, uncertainties tend to be coupled, so that if one factor is not as positive a feedback as expected, some other related factor will not be as strong a negative feedback so that the net effect on climate sensitivity is small. This is the case, for example, with the water vapour/lapse rate feed back. It is also partly because for factors where the uncertainties are independent, the final values will likely show not bias. So, for example, evidence is currently showing the ice/snow albedo feedback to be much more positive than is found in models. I do not conclude from that that climate sensitivity will be higher than expected because, odds are that some other factor (or group of factors) will show a lower sensitivity. Perhaps that factor will be climate sensitivity. We can hope that the coupled Global Circulation Models are all biased in favour of high climate sensitivities, but assuming that they are is neither scientific nor skeptical. Consequently resting your expectation of low climate sensitivity on just one factor is selective reasoning. More importantly, climate sensitivity is not just estimated from models. Estimates of climate sensitivity from paleo data, by definition, do not underestimate or overestimate any feedback. As paleo data consistently suggests climate sensitivities around 3 degrees per doubling of CO2, it is a very reasonable assumption that particular errors in estimating particular factors in coupled GCMs will cancel out. Given that, although you may think the evidence favours a low climate sensitivity, acting as though there is not a high probability that you are wrong is foolish. Turning to the other side of the equation, assuming 2.5 < the climate sensitivity < 3.5, the US and Australia need to eliminate all CO2 emissions by 2020, either by direct reduction or by purchase of overseas carbon credits, if we are to not face massive ecosystem failures. If the climate sensitivity is greater than 3.5 degrees C per doubling, those eco-system failures are probably already locked in. As a simple fact of economics, decarbonizing the economy in 20 years is a huge economic task. Doing so in 10 years or less will destroy the economy. So, suppose we act on your assumption that climate sensitivity is between 1.5 and 2.5 degrees per doubling of CO2, but that in 10 years we find out the IPCC central estimate was more accurate. By not acting now we have committed ourselves to destroying the economy by decarbonizing, of of having it destroyed by massive ecosystem collapse within a generation or so. In contrast, suppose we act on the supposition that the IPCC is correct, but in 10 years we find out that you were correct. Well, then we are ahead of the game, and can slacken of the effort. We have lost very little in the process. We are like drivers setting ourselves up for a turn. We know we have to turn sometime. By breaking later, if we make the turn, we will gain an advantage in terms of economic growth (which is not to be sneezed at). But by breaking later we significantly increase the risk of not making the corner. As it happens, our navigator is telling us "Brake, brake, brake" and has his fingers firmly grasping the dashboard with white knuckles. In the meantime we are pushing a little harder on the throttle and saying, "Not yet!" Of course, economies and ecosystems do not steer like rally cars. Rather, they steer like super tankers. You can see why I don't want your putative congressman at the wheel. Like most elected politicians, s/he's all about the short term electoral cycle, with no thought to the long term consequences. -
Tristan at 01:19 AM on 1 October 2011Understanding climate denial
People become attached to their opinions. Opinions represent who we are, and accepting that an opinion of ours is wrong comes at a substantial personal cost. The cost rises when your opinion is also the basis for your job/hobby/friendship circle/fame. People can go to amazing lengths to retain their opinions. A bit of cognitive dissonance is easy enough to maintain. Consider Monckton's plight. If he changes his mind about AGW he has to face two nasty thoughts. A) He isn't as clever as he thought he was and needs to do some serious grovelling and B) He aided and abetted a system that imperils the life and prosperity of the planet. If anyone wants a shining historical example take a look at Millerism. -
robert way at 01:16 AM on 1 October 2011Climate Change Could be Expensive for Canada
Jonathon, Increased wintertime temperatures may lead to more deaths rather than less. You have to recognize two things, first that warmer temperatures will result in greater extreme precipitation events in Canada and greater variance; and secondly (most importantly) a lot of Canadians travel on ice in the North. I've already first hand seen (I'm from Northern Canada and of Inuit descent) the increase in people going through the ice on skidoo and getting into dangerous situations because of dangerous ice conditions due to increase wintertime warmth. We are far better suited up here to deal with cold than we are with heat. -
Composer99 at 01:06 AM on 1 October 2011Climate Change Could be Expensive for Canada
Jonathon: With regards to: Likewise, the increased deaths due to warmer summertime temperatures were included, but not the decreased deaths due to warmer wintertime temperatures. In a country where cold is a bigger issue than warmth, I would think this would be rather relevant. I would not be too sure of this. While one would have to go to Statistics Canada or a similar source to get a full picture, I have found these links to some major cold- and heat-related weather events on Environment Canada's website. The events at the bottom of the pages are, I am led to understand, the biggest in the database. There is a single heat wave event (to be fair, in the midst of the Depression) with 1,186 recorded fatalities; a number two orders of magnitude greater than that of any of the cold snap events with fatalities themselves. Perhaps I shall look into this more on the weekend. At any rate, even if Canada were to find that, at the national level, the benefits of global warming outweighed the costs, these benefits would not be evenly distributed regionally within Canada, and of course they would pale in comparison to the costs of low-lying, sub-tropical and tropical regions (e.g. Louisiana, Texas, Florida, the Netherlands, Bangladesh, &c, &c). -
cRR Kampen at 01:00 AM on 1 October 2011Understanding climate denial
#128, Well yes Albatros, I sometimes do prefer 'graphic' for clarity - then quite often have a good laugh at the response or total lack of it... I wonder how any taboo could be illustrated by non-graphic examples of it. Anyway, the argument made there is rather subtle, or let's say 'philosophical'; I think the message was clear at least for those interested. 'Facts are taboo' describes a typical denier's reaction to facts. Reactions like: flying into a rage, or running away, or censoring - the works. -
DSL at 00:59 AM on 1 October 2011Review of Rough Winds: Extreme Weather and Climate Change by James Powell
Norman: "Two other meteorologists do not share Jeff Masters Expert Opinion. One is Anthony Watts and the other Joe Bastardi. Both of them are meteorologists that have been in the field for many years. They would see similar data that Jeff Masters is exposed to. Why don't they see this same extreme year?" You've asked the right question, Norman, but for the wrong reason. -
Dikran Marsupial at 00:55 AM on 1 October 20112011 Sea Ice Minimum
This is what you get if you use a quadratic covariance function, giving a Bayesian alternative to Tamino's model (well closeish anyway)
This gives rather poor predictions for the last two years:
prediction for 2010 = 5.414904 (+/- 1.124377)
prediction for 2011 = 5.338500 (+/- 1.130803)
prediction for 2012 = 5.262056 (+/- 1.137584)
However Tamino's model had more data to work with, so it is possible that with more data the model will decide that there is more curvature and less noise in the data than at present.
I still think Tamino's method is better; I suspect the problem here is that the model has a couple of hyper-parameters that have been optimised, whereas a proper Bayesian would integrate them out. It may be there are two ways of explain it the data, high curvature/low noise and low curvature/high noise and the optimisation approach only finds the latter, whereas the simpler frequentist approach finds the former.
Self-skepticism is vital in statistical analysis, which is why I greatly prefer a physical model over a purely statistical one.
-
Albatross at 00:48 AM on 1 October 2011Understanding climate denial
cRR@126, Actually, I did understand, they were good examples, the content though was not really consistent with that we prefer to use here at SkS..that is all. You are welcome to try again using less graphic terms. -
Dikran Marsupial at 00:45 AM on 1 October 20112011 Sea Ice Minimum
Tom Curtis yes, the further away you extrapolate the less reliable the projection gets, just on statistical grounds, whether you use Tamino's method or mine. If you look at the credible interval for the ice free Arctic, the model is basically saying it doesn't really have any idea of how soon it will happen, other than it is unlikely to be before 2027 (the upper limit is effectively at infinity). I don't mind saying what the model says about when the Arctic will be ice free in Summer, but I wouldn't make a serious prediction about it. -
Tom Curtis at 00:40 AM on 1 October 20112011 Sea Ice Minimum
Dikran @29, you may prefer Tamino's quadratic model, but he specifically disavows trusting its indicated trend except in the short term and, last time I looked, refuses to make a prediction about how soon until a zero ice minimum in the Arctic. -
John Hartz at 00:40 AM on 1 October 2011Understanding climate denial
@rcglinsk #114: If the majority of the American public are not convinced that manmade climate change will severely impact the Earth's ability to sustain life as we know it, our elected representatives will never implement mitigation and adaption actions commensurate with the magnitude of the problem. -
Tom Curtis at 00:37 AM on 1 October 2011Sea level rise due to floating ice?
Jonathon, Jose, my understanding is that Forster was involved in the decisions of the IPCC, and that he disagrees with the interpretation in the cited article. In fact he states:"Firstly, Thanks for the interest in our paper and much useful discussion. I think the blog analysis is roughly correct, but I disagree completely with its interpretation. I disagree strongly that the IPCC authors were at fault for changing the priors and I disagree strongly that the uniform feedback prior is the best choice. Thirdly I disagree on the significance of all of this. I’ll deal with each in turn 1) I was fully aware about the use of our data and the choice of priors by the ipcc. However, my paper was published so I didn’t need to approve of it’s use by IPCC, as it was is the public domain. In fact to keep the chapter as objective as possible I did not get involved in the assessment of my own paper and was happy to let my expert colleagues decide on it’s merit or otherwise. I also believe that the work put into assessing our paper by the IPCC authors is in fact a great testament of their professionalism. Rather than take our published numbers at face value, they looked very carefully at our paper and took the deliberative step, using their statistical and climate expertise, to modify our results to a uniform prior in sensitivity. They plainly state this in the report and are not trying to hide this. They also did this for sound science reasons based on the current literature at the time and acknowledge the problem of choosing the right prior in the chapter. Like Nic, I personally really like Non-GCM ways of estimating sensitivity, but I quite understand why IPCC didnt give it any more weight than any other study. The major problems with FG06 are the short time period of observations, regression errors and satellite data errors. This was again a perfectly sound example of expert assessment. 2) Nic keeps mentioning OLS regression as the physics- based correct method, and that using this means that one should choose a uniform prior in feedback. If you read FG06 we infact spend a lot of time worrying about the choice of regression model. In the end we went for OLS, but this choice is not clearcut in complex systems where everything is interacting and isolating cause and effect becomes hard. All this means is that, as Annan Points out in his climatic change paper, the choice of prior isn’t an easy call and is very subjective. There is no one right answer for the best prior choice. 3)My third point is that in the meantime, just as Fred Moolten points out above, the science moves on. The work by James Annan shows clearly the effects of different prior choices and that there is not one “correct” answer. Gregory and Forster 2008 and other papers show how high sensitivities don’t really make any difference to current climate change rate, as high sensitivities slow down the system response. Finally, we have repeated FG06 with updated observations from ERBE and CERES in Murphy et al. (2010), JGR D17107 and got a median climate sensitivity estimate much higher, around 3. 0 C. Note that the murphy paper quotes a feedback value of 1.25 watts per square metre per K. We deliberately did not invert for sensitivity as we are unclear how representative these values are for the longer term climate response."
Clearly there is no issue here. What is an issue it your desire to pursue off topic comments in violation of the comments policy. Where I a moderator I would have simply deleted Jose's original comment in total. If you are so discourteous as to deliberately flout comments policy rules, you are owed zero extra effort by the moderators to ensure that your on topic comments stand. Is it really too much to ask that you seek out an appropriate thread for the discussion rather than try and divert discussion where it is not relevant? As it stands, I think it is certainly appropriate for the moderator to even now snip your original post and all responses (including this one). -
Dikran Marsupial at 00:34 AM on 1 October 20112011 Sea Ice Minimum
Bernard J. it would be interesting to look at that as well. You are right though that my earlier post was just a game. The thing I am really interested in is how the credible interval changes with the amount of data avalable. The problem with a Bayesian approach is that the outcome can be heavily dependent on the prior assumptions. The model I gave earlier gives nice looking projections, but the prior assumptions are not really supportable (it assume a-priori that sea ice extent will fall to zero at some point, which I suppose is supportable by the physics of the enhanced greenhouse effect). Tamino's analysis makes fewer, more supportable assumptions, so it is more trustworthy. -
Bernard J. at 00:23 AM on 1 October 20112011 Sea Ice Minimum
Dikran Marsupial. Interesting game. What happens when you plug in the sea ice volume values? -
Dikran Marsupial at 00:15 AM on 1 October 20112011 Sea Ice Minimum
Tom Curtis The error bars are so broad that I wouldn't want to infer anything from just two points. If I can make a model that I have a bit more confidence in it may be worth looking at in more detail. I have more faith in Tamino's quadratic model. -
Tom Curtis at 00:08 AM on 1 October 20112011 Sea Ice Minimum
Dikran Marsupial @25, a very pretty graph. Am I correct in my estimate that the last data point is 2009? If so, given that 2010 and 2011 are both below your trend (red) line, doesn't that suggest that a model which does not go from a trend of accelerating loss to a near linear loss is more likely than the one that you show? Does it not follow that, on current data your 2041 "prediction" for ice free summers is optimistic? I hope Dana will be kind to you ;) -
Jonathon at 00:07 AM on 1 October 2011Sea level rise due to floating ice?
Jose, We are getting off topic, and the moderator is likely to step in and discontinue this discussion. Scientifically, a normal distribution is considered most probably unless a constraint is placed on one end (such as counts cannot be negative or exceed 100% of the population). Reading the report, I can see no reason why a normal distribution would not be acceptable. The article does indicate that the IPCC showed bias (actually the article was not that polite) in displaying a non-Gaussian distribution. A better reference would be something like based on- or derived from- the data... In your super dense liquid scenario, if we assume that the ice covers the entire surface area of the liquid, then the melting of the ice would raise the liquid level to same height as the liquid + solid starting height. -
Dikran Marsupial at 00:01 AM on 1 October 20112011 Sea Ice Minimum
muoncounter you do have a point, as Einstein said, "there are only two things that are infinite, the universe and human stupidity - but I'm not sure about the universe". I suspect Einstein foresaw the blogsphere! ;o) As my predictions are more accurate that the WUWT committee projection, it would be a poor reflection on them indeed if the skeptics say we are using a chimps'n'buckets approach! -
Review of Rough Winds: Extreme Weather and Climate Change by James Powell
Norman - I'm going to rejoin those various bullets, as I believe the whole is greater than the parts. It's my opinion that you have indeed made a number of claims in this (and related) threads: * Extreme weather has not increased. I may have overstated this - what you are actually asserting is that it's impossible to prove that extreme weather has increased. That seems to be a firmly held opinion, and I believe is leading you into confirmation bias, shaping what evidence you find acceptable. * Records of disasters are biased by population shifts/changes, and no actual event changes have occurred. Hence the insurance information and FEMA disaster records are inaccurate. This postion is based upon the research of Pielke. Disaster as a proxy for extreme weather events is questionable. This is an extremely strong statement, claiming that a particular dataset is invalid support. References? If it's based upon research, please point to the references involved. As you may be aware, there has been considerable discussion of Pielke's preference for regional climate over global indicators, to the extent that some (and I include myself) consider it a distraction from the global issues. I do not recall anything from Pielke stating that regional events have not changed recently. You have not (IMO) justified the "Disaster as a proxy for extreme weather events is questionable" statement. Money talks, and I would consider the Munich RE data extremely informative as a result. Perhaps the data is biased by economic events - if so, how, by how much, and how might that data be corrected? Those are reasonable questions if the evidence indicates error/bias in the data. You haven't taken that first step. * Earthquake numbers are underestimated due to better building codes. * Reporting codes (for weather only, not earthquake, a peculiar distinction) have changed to increase disaster reports. Here is what my post said. "I have one possible explanation. Not necessarily a good one, maybe you won't accept it. Here goes." Lacking evidence, this is a "Just So Story", not science. See also Wishful Thinking. --- and finally, the nail in this particular coffin: What I am doing is not cherry picking, it is random picking. It would be like reaching blindfolded into a basket and pulling out cherries at random and presenting this. I go to the NOAA site looking for past examples of severe weather events. I just picked a date a random that was far away from recent times and presented it to demonstrate that extreme weather takes place maybe more often than a randomized statistical approach would allow. (emphasis added) In other words, you searched for extreme events at other times, ignoring statistical indications and trends, in order to present possible counter examples. This is classic cherry-picking, Norman. It's (from the definition, "a kind of fallacy of selective attention"), hunting for the subset of data that supports your hypothesis and ignoring the mass of evidence that might contradict you. You've done this with (as I recall) just Dallas weather rather than Texas, just days >105 rather than mean temperatures, selected dates from history rather than trends, on and on and on as others have called you on your data selections. At this point, with cherry-picking firmly established as a core of your arguments, I'll have to take this as evidence that the Extreme weather has increased hypothesis is rather strongly supported by your inability to disprove it. -
Modern scientists, following in Galileo’s footsteps
34 - John Russell I think you are right - there's a great deal of selection bias going on. I personally don't like either this posts attitude to Galileo, nor the Galileo 'movement's etc. For starters, if Galileo hadn't been so bloody minded and therefore become a semi-martyr, he'd have gone down in history as a fine instrument maker with a great imagination for measurement. In a more moderate (less hero-oriented) history Kepler is the one with a slightly idealistic theoretical bent, but who was prepared to the the hard slog on Tycho Brahe's data to set up the phenomenology for Newtons theories. Kepler stood up to just as many religious barriers - only not Catholic ones; and, lets face it, the Vatican is the ultimate symbol of power to stand upto... these days we see the Protestants as a push-over even though they where a pretty blood-thirsty lot in Galileo's time. The whole Galileo story being scrapped over here is just a 'mythology' we use to ground modern - enlightenment based science. I'm all for that; but it must be seen for what it is. If anyone should be compared to any of the 'heroes' of the past... it's those folks who spend 10s of years up to their back-sides in snow or mud gathering data, or designing better satellites, or sweating over the last 0.00x% systematic error in some small, new measurement which fits into the whole corpus of knowledge. A few, very few, people have the breadth to put together the big picture, a few more contribute to communicating that picture - the rest is sophistry.
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