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Dikran Marsupial at 03:19 AM on 21 April 2012Murry Salby finds CO2 rise is natural
@spherica estimating the sensitivity of natural changes in CO2 to changes in temperature is a worthwhile question, but the answer is only 8-9ppmv per degree centigrade. Salby is essentially making the same mistake as Spencer in noticing that there is a correlation between temperature and the annual change in atmospheric CO2. However if you differentiate a long term trend (to get the annual change) any linear increase becomes a constant, and the correllation only explains the variability around this offset, it doesn't explain the offset itself, and hence doesn't explain the long term increase in CO2. I really hope Prof. Salby withdraws the paper (I have sent him an email pointing out this error) his other work is apparently very good and it would be a pity for him to tarnish his reputation. -
Bob Lacatena at 02:47 AM on 21 April 2012Murry Salby finds CO2 rise is natural
Stephen, I think the single biggest nail in this whole coffin is that human emissions have extracted 337 Gt of carbon from the ground and turned it into CO2. So any "natural source" argument must both (a) come up with a comparable source of carbon (which would be utterly huge, and unheard of in the past 800,000 years where atmospheric levels have never topped 300 ppm) and (b) a sink to absorb and completely hide the human emissions. As well as some rationale which explains why the sink works on human emissions but not natural emissions, so that the atmospheric and ocean CO2 increases are "entirely natural" while human emissions magically disappear into thin air and have no effect on anything. This, to me is complete and total denial in a nutshell. To make this sort of twisted, impossible, Alice-in-Wonderland argument work requires such a Lewis-Carrollian pretzel that it clearly demonstrates a mind in utter and complete denial of reality. -
sidd at 02:43 AM on 21 April 2012Why Are We Sure We're Right? #1
1) What am I sure about? Simply put, I am sure that adding fossil CO2 to the atmosphere will warm the surface and I agree with the IPCC confidence limits on Charney sensitivity. 2) Why am I sure ? Because I have the math and physics background to understand the argument and the calculations. 3) What would it take to change my mind ? Some process would have to be discovered that masks the warming effect we expect from releasing fossil CO2, together with another process which causes the same amount of warming that we expect from releasing fossil CO2. I am reminded of "Through the Looking Glass" "But I was thinking of a plan to dye my whiskers green, And always use so large a fan, that they could not bee seen" 4) I am certain enough of 1) that I personally waste no time at all on trying to find mechanisms for 3) sidd -
Bob Lacatena at 02:42 AM on 21 April 2012Murry Salby finds CO2 rise is natural
Dikran, Actually I think he goes further wrong in the step before that, starting at 20:00. He says:… sensitivity… how much net emission of co2 is increased by an increase in temperature, or soil moisture. Because they are incoherent with human activity, they can only represent emission from natural sources. If you know that component from net emission, you can add it from one year, to the next year, and so forth. The total then represents the contribution to the observed CO2 from natural sources.
His flaw is that he sees that changes in temperature correlate well with changes in CO2, as we all know they do and thoroughly expect (due to changes in solubility of the oceans). But he then conflates that well understood and even quantifiable mechanism with the idea that therefore any other mechanism (human emissions) is mere noise, and that therefore the obvious, visible effect must be the cause of the net increase. Interestingly, this presumes some magical source of carbon that he not only fails to identify, but never even attempts to mention or address. This is exactly equivalent to noting that clear skies and clouds cause the largest daily changes in temperature, and therefore the net increase in temperature as the seasons change from winter to summer must be entirely a result of the cumulative, net change from cloud cover but not from the change in the angle of incidence of sunlight over many months (because that net daily increment is small, and "is not coherent" with daily temperature changes). I hope in his paper he takes the time to do some real science, i.e. to compute the changes in partial pressure and solubility in the ocean and atmosphere for each year, to compute the expected change in CO2 from these levels, and then to make some effort to identify the source of the discrepancy. Gee, I wonder what it could be? -
Stephen Baines at 02:40 AM on 21 April 2012Murry Salby finds CO2 rise is natural
Beside the mass balance and stable isotope arguments, there is the fact that ocean pH is decreasing and pCO2 in the ocean is increasing in the surface mixed layer. If increasing temperature were causing the observed atmospheric CO2 increase by outgassing, you would see the opposite. Faced with that, he should have been, at the very least, motivated to try to find an alternative intrepretation for his observations. ` -
Dikran Marsupial at 02:04 AM on 21 April 2012Murry Salby finds CO2 rise is natural
You can see Prof. Salby's talk here and I would strongly recommend anyone interested in the topic to watch it. The key error is introduced in the slide at 21:08; more or less every scientific point prior to that appears essentially correct, but completely uncontraversial. @Sascha Tavere, the uptake of CO2 by the oceans is dependent on temperature, but also by the difference in partial pressure between the surface ocean and the atmosphere. The equilibrium warming due to CO2 increases only logarithmically, but the pressure relationship is IIRC linear, and opposes the change. I suspect this is the feedback that Salby had in mind, but I don't know why he didin't just say so. -
Bob Lacatena at 01:57 AM on 21 April 2012Why Are We Sure We're Right? #1
Dana, See, that's my problem. The more strategically minded deniers seem to have adopted the strategy that they can take and dismiss one, single, ridiculous position that is supported only by the nut-jobs of the world (the slayers), i.e. that the GHG effect violates the laws of physics. By so doing, they try to imply that they are the center, the denial nut-jobs are on one fringe, and the entire rest of the professional climate science community represents the other fringe. But they also continue to accept other utterly simple and easily refuted arguments, specifically whether or not the globe is warming (Watts on BEST, Spencer with his recent UHI analysis, Curry with too short a trend) and also -- and this is really, really just downright laughable -- the source of increased carbon dioxide in the atmosphere. I mean, really... the CO2 arguments are just so basic and simplistic that anyone who tries to go there should have a giant D (let's be nice and say that's for "dunce") branded on their heads... particularly if they are "excellent" scientists like Salby or Curry. Even Singer refutes the "natural CO2" argument in "Climate Deniers Are Giving Us Skeptics a Bad Name." I think it's time for scientists who are literally embarrassing the field to be publicly embarrassed themselves. I mean, it's almost a little too easy for me to accept that I'm right when the most "professional" and "excellent" scientists that are in denial are putting forward insanely stupid arguments (Salby on the source of CO2, Curry on Salby revolutionizing climate science, Spencer on surface UHI when his own work demonstrates the opposite in the troposphere). Why are we sure we're right? Because the deniers invest so much energy into coming up with things that are laughably wrong. -
Dikran Marsupial at 01:30 AM on 21 April 2012Why Are We Sure We're Right? #1
Like Dana, I am disspointed to hear that he has not reconsidered. Sadly it seems he will be ruining an otherwise excellent academic career (see his publication record). Unfortunatly once someone has an incorrect idea in their heads it can be difficult for them to accept that they are wrong, counterintuitively especially of the proof happens to be very simple. I suspect being a genuine expert in one field makes one particularly prone to this (c.f. Dyson). If Salby's paper appears in a decent journal, there will be comments submitted, even if I have to do write it (again! ;o). I did post Salby a pre-print of my Energy and Fuels paper, but recieved no reply. -
Uncle Ben at 01:15 AM on 21 April 2012Roy Spencer finds negative feedback
DSL: " The point is that you can indeed calculate sensitivity in a complex system; you just can't calculate it with the precision of a closed mathematical system." I agree! In fact, Spencer has provided us a way to improve the estimate of sensitivity. By separating the trajectory of dH/dt vs dT into segments in which the effect of dH/dt and the non-radiative forcing that creates clouds in the absence of strong dH/dt, he has been able to estimate the slope of the regression of the latter. He finds that the slope is about 6 in the usual units, as opposed to 2.5 using the combined data. This yields a sensitivity low enough to show that the feedback from dH/dt causes is negative. Doubling CO2 then is seen to cause only 0.5 deg. C of warming. Not much calculation is needed, in fact. If you take the trouble to look at his plots, you will see that the straight-line segmenmts are numerous, parallel, and obvious. It is quite convincing. It is their slope which gives the sensitivity to dH/dt. The plots are so clear in showing the straight-line segments that the precision is much higher than that of the widely scattered estimates of sensitivity found by other means. We know now why they are widely scattered. A variable has hitherto been ignored. -
dana1981 at 01:06 AM on 21 April 2012Why Are We Sure We're Right? #1
Sphaerica @9 - to be fair, Watts has joined Singer and Spencer et al. in denouncing the 'sky dragon' hardcore deniers. That said, Watts seems to embrace virtually any other "it's not humans" argument on his blog, Salby's nonsense being the latest in an incrediby long line of ludicrous examples. But at least he did draw the line somewhere! Tom @14 - that's disappointing. After not hearing a word from Salby in 8 months I was hoping like Dikran @13 that he had come to his senses. Given his comments on Spencer and Braswell, clearly that's not going to happen. TOP @11 - I'm sure John would say the point of the handbook is that although we can't be certain, the scientific evidence does overwhelmingly support AGW, and that's what we need to communicate to people. -
Bob Lacatena at 00:59 AM on 21 April 2012Why Are We Sure We're Right? #1
13, Dikran,I gather he is an excellent scientist...
I find this utterly impossible to accept. The concept that small variations can overwhelm a consistent but important underlying signal (i.e. natural variations paralleling global temperature swings versus regular, cumulative addition through human emissions) is literally the simplest thing in the world to grasp. No reputable scientist could possibly make that sort of mistake, and then trumpet it in public as an upcoming, landmark paper. At the same time, his failure to explain or even address where human emissions might have gone (if not into the atmosphere and ocean) as well as where the actual increase could come from (given that CO2 has never risen above 300 ppm in the past 800,000 years) is quite simply unacceptable. His argument amounts to the same denial argument with regard to temperature... an inability to distinguish a trend from the noise. This is basic, basic, basic. He demonstrates either willful ignorance or complete incompetence. In either case, "excellent" cannot come anywhere into this equation. -
Tom Curtis at 00:57 AM on 21 April 2012Why Are We Sure We're Right? #1
Dikran Marsupial @13, apparently this was Prof Salby's position on Feb 20th:"Dear Brian, Apologies for the belated reply; we’re on summer break here. The technical paper underpinning my presentation to the Sydney Institute has certainly not been withdrawn. The cycle of scientific publication is slow, typically about a year. For a subject as political as this one, it can be very slow. The fiasco surrounding Spencer and Braswell (2011), a thinly-veiled exercise in coercion, didn’t help. But, with patience, we will eventually get there. Upon formal release, a notice will be sent to the numerous interested parties. In the meantime, a couple of matters of possible interest: (1) About half of the material in the Sydney Institute presentation is developed in Physics of the Atmosphere & Climate, a peer-reviewed volume that is now out. Although developed for a technical audience, elements should be comprehensible to the non-specialist. Highlighted in the attached is material of relevance. (2) In the coming weeks, a video of the presentation will be made available through the Sydney Institute – inclusive of full graphics. Stay tuned. Murry Salby"
So apparently, no he has not seen reason. But any difficulty he has with publishing is purely to do with politics and nothing to do with any flaws in the paper /sarc -
dana1981 at 00:46 AM on 21 April 2012Global Surface Warming Since 1995
Sphaerica @9 is correct. If only considering temperature data, as with Santer and Jones in the first part of the inteview, the question is simply whether the average global temperature has increased. Attribution of that warming, while an important question of course (one which I've explored in many SkS posts), is a different subject which requires more information. -
Dikran Marsupial at 00:28 AM on 21 April 2012Why Are We Sure We're Right? #1
To be fair to Prof. Salby, I gather he is an excellent scientist, it is just that he has made a serious error on this particular point. I suspect that the journal paper that was mentioned at the time has been quietly withdrawn by Prof. Salby after having seen that the various counter-arguments following his presentation are entirly correct. -
Sascha Tavere at 00:19 AM on 21 April 2012Murry Salby finds CO2 rise is natural
@ Dikran Marsupial Re Q&A Audience question: "... more temperature -> more co2 -> more temperature? ..." (4'30") Murry Salby: "For reasons that I am not going to go into with this audience, there has to be a negative-feed back that bridles this positive feed-back and holds things in check." Oh yeah? Do tell more professor Salby! He didn't. There just "has to be". Am I offended because of the condescension? It might not be possible when speaking to lay people to explain everything in a short space of time, but it seems to be a crucial point that you can't hedge on if you're serieus. Pique or scepsis? -
DSL at 00:14 AM on 21 April 2012Roy Spencer finds negative feedback
Uncle Ben: "3. The little model demonstrates a mathematical fact, which is already obvious to students of statistics, namely that you cannot compute the sensitivity to one variable if another hidden variable is varying the output." Welcome to the geophysical sciences. I hope you had a nice stay in the math department. Every day, you manage to make decisions based on intuitive modeling where one or more variables are unknown. You've managed to live, so far. You've probably actually learned from this daily type of intuitive modeling. You've probably made important decisions based on weather forecasts, which use the same type of modeling. The point is that you can indeed calculate sensitivity in a complex system; you just can't calculate it with the precision of a closed mathematical system. Roy knows that. You should know it. And the unknown variable in this case is not all that unknown. I'll wager that you yourself won't accept certain values for it. -
Bob Lacatena at 00:12 AM on 21 April 2012Global Surface Warming Since 1995
7, Slioch, No. Santer is only discussing whether or not it has warmed, but from the frame of reference that if there were anthropogenic warming then you would have to have 17 years to see any warming (natural or anthropogenic). Santer is not discussing attribution of that warming, and neither is Phil Jones with his "statistically significant" response, and neither is this post. If you wish to discuss it, please do so on the "It's not us" thread here. Your inclusion of Phil Jones' answer to a later question about attribution and your (mis)interpretation of Foster and Rahmstorf (2011) inappropriately steer the discussion in that direction. No one is saying that it's not an interesting or important question. Only that this isn't the place to discuss it. This thread is about Santer and whether or not the earth has warmed in the past X years. -
Global Surface Warming Since 1995
Slioch - "For example, any period of a few years leading up to the great El Nino of 1998 would show warming, and that warming would be statistically significant in the terms that you have used..." That would be incorrect, considering that the question is not "is it warming/cooling" (think summers versus winters, definite temperature changes), but "whether average temperatures are warming/cooling", a long term (climate) trend over and above normal variations such as ENSO. Such a trend identification requires a fair bit of data - enough that the uncertainties induced by variation and measurement errors are low enough for a "no trend" line to fall outside the generally accepted 2 standard deviation range (95%) range. Second to that is attribution, where we have to look at our available data on possible forcings (insolation, aerosols, albedo, greenhouse gases - anything changing) to see which of those is changing, and how, and for purposes of our own deciding whether to change the forcings under our control. As to your examples, I would have to agree with Jones - complete confidence that the climate is warming, extremely strong evidence that the major part of it in the last half century is due to us. But F&R did not address any attribution issues, they simply looked at better identification of the trend outside identifiable variations. And Santer et al were also looking at trend identification, not attribution. These are different questions. -
DSL at 00:04 AM on 21 April 2012Why Are We Sure We're Right? #1
Eric - the focuses are tied together in a dynamic relationship. The stronger the evidence becomes for current estimates of sensitivity, the stronger the need to counter the bull**** with . . . well, a strong response. TOP - "certainty," for me, is that level of confidence that allows action to take place in good conscience. I make decisions every day that are based on less than certainty, and I worry about those decisions, but I am forced to act. The level of confidence I have in current mainstream estimates of sensitivity allows me to currently act toward mitigation in good conscience. How someone can, after having looked at the thousands of studies available and the history of the science, come to the confident conclusion that climate science is a hoax baffles me. If John is willing to publicly commit to the idea that "AGW is occurring and that is the absolute, unalterable Truth" then I'll buy a hat and eat it. I suspect he would rather say, "The overwhelming amount of work done by scientists suggests that AGW is occurring, and the suggestion is so strong that I can act as if it is the truth, even if I am still open to the idea that the science may be overturned." Show me a person who claims to have found absolute truth, and I will show you a person who is demonstrably wrong on a regular basis. -
TOP at 23:43 PM on 20 April 2012Why Are We Sure We're Right? #1
You have touched upon a major point in John Cook's book, "the Debunking handbook" that has always troubled me. The point of view that John took in the book was that one party was absolutely right and trying to convince the unconvinced to the truth of what that right notion was. Then I see Dikran Marsupial starting off with, "I don't think that we are sure that we are right, as science is never completely settled; we can be confident we are right because the available evidence very strongly supports our position*;" followed by Ari Jokimäki stating, "But in any case, I don't try to be right about anything.". These are positions close to my own and just don't jive with taking a position like John took in his book which seems to require absolute certainty. Glenn Tamblyn's position is much closer to John's IIRC. -
Eric (skeptic) at 23:41 PM on 20 April 2012Why Are We Sure We're Right? #1
muoncounter, no doubt there is a lot of stubborn refusal to accept the possibility that we could warm into unknown and dangerous territory with doubled (or more) CO2. But your list is the "noise". The "signal" is how high sensitivity "stands with basic physics" (or not). You have no choice but to counter the noise as it lands in the media or on your doorstep, but it should not be the main focus. -
Bob Lacatena at 23:19 PM on 20 April 2012Why Are We Sure We're Right? #1
Contrast this with the WUWT post submitted by caerbannog. I mean, really... is Anthony Watts still attempting to promote as dead an argument as the idea that the source of CO2 increases in the atmosphere is natural? Really? He either truly doesn't get that simple, irrefutable fact (in which case the Comments Policy forbids me from saying more on that subject) or else he does know it, and is posting an argument like that any way (in which case the Comments Policy forbids me from saying more on that subject). In recent months we've seen a number of moderated "yeah, well, maybe, but..." comments from the likes of Spencer, Singer, Pielke Sr. and others. Each of them is trying to to some degree distance themselves from the indefensible, wing-nut, denial claims that make them all look silly (like arguing that the source of the added CO2 in the atmosphere is somehow natural in origin). They've tried to paint themselves as reasonable moderates in the center of the debate, while certain other factions at the edges are deniers (but no, not them!) or "alarmists." That by itself is silly, but... The wing-nut element is still there, and they still cling to it when they like, such as Anthony's latest post on CO2 levels, where he has the unmitigated gall to say:He elegantly shows that there is a solid correlation between natural climate factors (global temperature and soil moisture content) and the net gain (or loss) in global atmospheric content when the latter is averaged over a two year period. The hanging question remains, if natural factors drive more than 90% of the growth in CO2 how significant is the contribution of human generated emissions. The answer is simple… not very.
I know why I trust my understanding of the science (which is different from knowing that I'm right), but the question that really intrigues me is... How do I know they're wrong? Because those in denial of anthropogenically triggered climate change are themselves inconsistent, or rather, they consistently argue the same thoroughly debunked topics. I know they're wrong because they try to score points and engage in propaganda rather than discussing the actual science. -
Uncle Ben at 23:19 PM on 20 April 2012Roy Spencer finds negative feedback
@Moderator 1. The reason I say that some clouds cause, not global warming and not ENSO nor PDO, but inaccurate measurement of sensitivity, is that they vary the temperature anomaly in time and are not caused by the current energy imbalance. In this way they reduce the regression slope, and thus corrupt its interpretation. 2. Nevertheless, what is of interest in this question is the idea that a rise in temperature reduces cloud cover and further increases temperature. Climate science does find this crucial for water-vapor feedback. 3. The little model demonstrates a mathematical fact, which is already obvious to students of statistics, namely that you cannot compute the sensitivity to one variable if another hidden variable is varying the output. @skywatcher - Data from the past includes, as you say, forcings of unknown and perhaps numerous sources. As we cannot measure these forcings now. That means that we cannot remove their effects for the purpose of estimating feedback. That is why it is so valuable to have satellite data, which gives us the forcings as well as the anomaly. Consider how data were adjusted to compensate for the eruption of Mt. Pinatubo. We can't do that for ancient data. Failure to correct for forcings other than the energy imbalance always affects the sensitivity in the same direction: it lowers the slope and raises the sensitivity. Also, science is not a horse race. Let us not try to handicap the jockey.Moderator Response: TC: Uncle Ben, if you do not stop double posting, I will start double deleting. -
muoncounter at 22:51 PM on 20 April 2012Why Are We Sure We're Right? #1
I particularly like Glenn's list. Compare it to a short list for 'the other side' to see how things 'balance' out: 1. No, its not. 2. Even if it is, it's not our fault. 3. Even if it is our fault, you can't 'prove' it. 4. Why? Because we know it's not. So there is overwhelming weight of evidence, logical consistency and thought on one side vs. very little beyond stubborn refusal on the other. Unlike Eric#6, I believe that certainty about basic physics is paramount and must be the focus of the real debate. Our argument stands with basic physics; theirs does not. Uncertainty about details is the stuff for the 'back room debate'; unfortunately, that is what gets dragged out in public every time there's another spring snowstorm or half-baked idea. -
Daniel Bailey at 22:34 PM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
I would note in passing that Mr. Haas has yet to fully articulate his position WRT the OP and has yet to attempt an answer to questions put to him over the past several days (other than to restate in muddled fashion his understandings...which run counter to the science). Given the elapsed time and his continued posting in this thread (which reveal an unchanged level of understanding of the science not in accord at all with the science), the inescapable conclusion one must draw is that we must move beyond the possibility of Mr. Haas simply misunderstanding the OP to the point of Mr. Haas prosecuting an agenda of dissembling. -
Cornelius Breadbasket at 21:35 PM on 20 April 2012Why Are We Sure We're Right? #1
What an excellent topic - and fastinating to see such varied responses from Dikran, Glenn and Ari. I would very much like to see a WUWT response to Glenn... -
Eric (skeptic) at 19:45 PM on 20 April 2012Why Are We Sure We're Right? #1
By far the biggest problem with sites like WUWT, which sometimes leaks over here, is that uneducated people look at a "debate" about basic physics and assume that this is somehow a mainstream scientific controversy. I would suggest rather than argue against bad physics why not show why the deep ocean "won't save us" or weather (increased water cycle) won't save us or simple thermal inertia in the big ice sheets or permafrost areas is insufficient to prevent melting within the next 100 years? I suppose part of the reason is that the bad physics people come here to argue their case and someone has to correct them. But claiming certainty about basic physics is not an answer to arguments that point out the uncertainties in climate science. For example, has anyone ever explained why models predicted a stronger polar vortex (less meridional flow) due to lower sea ice, now the models apparently predict a weaker polar jet and more meridional flow (due to lower sea ice). There are plenty of good threads on all of the issues that I have thought about here. That's where the real debate is, everything else is a "smokey back room" debate that does not belong in public. -
shoyemore at 19:00 PM on 20 April 2012Why Are We Sure We're Right? #1
caerbannog #1, Salby gave a public talk last year that was greeted with almost complete derision by scientists in the field. Since then he dropped out of sight. I do not think his musings have made it past peer review. It is not clear if he has even tried. There is a thread about his views here: Murry Salby confused about the carbon cycle The Irish comic writer Flann O'Brien has a scientist called de Selby in some of his books. Among de Selby's theories is one that night is caused by a gathering of atmospheric dust. I see a definite relationship. -
Doug Hutcheson at 18:10 PM on 20 April 2012Why Are We Sure We're Right? #1
caerbannog @1, I followed your link and my head exploded. The comments are delightful, though, so I copied a couple for the entertainment of SkSers:Smokey says: April 19, 2012 at 4:22 pm The central point should be that, obviously, the rise in CO2 is entirely beneficial. The biosphere is starved of CO2. More is better. I know that will make some folks’ heads explode, but that’s what happens when their cognitive dissonance meets reality. trevor says: April 19, 2012 at 4:25 pm I think this is one of the best posts of WUW I’ve seen. Good scientists present the data and let the audience make their own conclusions – exactly as Salby does in this lecture.
Good scientists present the data and let the audience make their own conclusions? When did that start happening? I thought good scientists publish their conclusions based on their data. Funny how wrong I was ... Good to know the estimable Salby is attracting friends at WUWT, as that is a good inverse-ratio indicator of the veracity of his claims. -
Slioch at 18:05 PM on 20 April 2012Global Surface Warming Since 1995
#4 dana1981 "the question here is whether it's warming, not the causes of that warming." Hmmm, no I don't think that is correct, but would welcome views on this issue. There are two questions, when examining a segment of a temperatures/time series of global surface temperatures such as HADCRUT or GISS (or lower troposphere UAH or RSS). The first is whether, taking into account the errors in the measurements, one is justified in saying that there has been a warming trend in the data over a particular period. For example, any period of a few years leading up to the great El Nino of 1998 would show warming, and that warming would be statistically significant in the terms that you have used: ie even taking into account the errors of measurement, a statistical analysis of the segment of a few years running up to 1998 would surely (say I, not having done the analysis!) conclude that there is a greater than 95% probability that warming, however caused, was occurring during that segment. Is that not the case? The second is whether any such warming is human induced. It seems to me that the sense in which you are interpreting the term 'statistical significance' is in answer to the first question, but that is not the issue, as far as I understand it it, that Santer was addressing. He was making a similar statement to that of Phil Jones in his famous BBC interview in February 2010, here: http://news.bbc.co.uk/1/hi/8511670.stm BBC - "Do you agree that from 1995 to the present there has been no statistically-significant global warming" Phil Jones "Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods." As far as I understand it, Santer and Jones were addressing the issue of whether the observed warming was due to human actions or not. After all, that is the interesting question, that is what people want to know: would the observed warming have occurred anyway, in the absence of human influences? Or can we state that there is a 95% probability that the warming is due to human actions and would not have occurred naturally? This the issue that Jones addresses explicitly later in the interview: BBC "How confident are you that warming has taken place and that humans are mainly responsible?" Phil Jones "I'm 100% confident that the climate has warmed. As to the second question, I would go along with IPCC Chapter 9 - there's evidence that most of the warming since the 1950s is due to human activity." That is also the issue that Foster and Rahmstorf (2011) address: if the main natural factors influencing surface or lower troposphere temperatures (solar, ENSO and volcanic) are (more or less) removed from the temperature series, is there a remaining warming trend that can be attributed to human influence? That is the question that they elegantly answer in the affirmative. They were not addressing the question of whether there had been any warming at all, but the causes of it. -
MA Rodger at 17:47 PM on 20 April 2012Why Are We Sure We're Right? #1
caerbannog @1 Your link certainly threw me straight into a "how do I know I'm right" moment. You point to an hour-long video posted at WUWT. Do I waste an hour of my life listening to the nonsense spouted by some Aussie Professor dude? The written introduction is as clear as mud. I could examine what the comments say about it, but at WUWT? No thank you! So why do I dismiss the vodeo as nonsense? If this Professor is 'right' that CO2 increases are natural, if his theories are more that total nonsense, I will surely meet them again presented in a better way in a better place. Yet I consider this an unlikely outcome. "Birds of a feather..." The people who accompany village idiots tend also to be of that ilk. -
NewYorkJ at 17:43 PM on 20 April 2012Why Are We Sure We're Right? #1
Ari has some insight... "Curiously, in many cases the same people who present their own claims with absolute certainty, go around saying that climate scientists cannot know anything because things are so uncertain. If uncertainty is their product, how come they are making their claims with certainty?" The highly-certain claims I think are a bit of Dunning-Kruger incompetence, as caerbannog puts it, but it's also used for rhetorical effect. Confident claims repeated many times resonate more among the general public than claims filled with the proper caveats or questions. The former is how politicians usually operate, but at least with politicians, there's some genuine scrutiny of and accountability for their words and actions. A true skeptic might ask "do climate models project periods of a decade with little warming and if so, what factors might lead to that?", then seek an honest answer. A denier would falsely but confidently assert "climate models predict it will get warmer year over year" but that hasn't happened" then cherry-pick some endpoints on a graph and assert CO2 doesn't cause much warming. Good skeptics are very inquisitive. From my observations, those calling themselves "skeptics" of climate science tend to not be very inquisitive, especially those who lack expertise (D-K Effect again). The uncertainty card is also played for rhetorical effect. The idea is to cast scientists as being arrogant and overly-confident in their beliefs, not humble and open-minded like skeptics. Another goal is to imply uncertainty means we know next to nothing. But if true, why are the same "skeptics" so confident? There's nothing to worry about, after all, except of course for the costs of mitigation, which will be catastrophic. And so the blatant contradiction. The two are sometimes combined in some sense. There are those who assert that uncertainty is higher than studies indicate, and those assertions themselves are stated with great certainty. The temperature record is unreliable, the IPCC doesn't appropriately capture uncertainty in climate sensitivity, models have no skill...the "we just don't know" statement carries with it the implicit certain claim that all of the evidence that would indicate otherwise is largely bogus. -
Kevin C at 16:09 PM on 20 April 2012GISTEMP: Cool or Uncool?
William: For GISTEMP, you can generate it for yourself here. Given that the others agree well over the region where they have common coverage, I see no reason to expect that the results will be different, however the grey areas will be bigger. For my own experiments with the HadCRUT3 data I see latitude bands in which only a single station is present right up to the present, and the results from such bands are essentially noise. -
caerbannog at 15:53 PM on 20 April 2012Why Are We Sure We're Right? #1
If this is a bit off-topic, at least it is *inspired* by this thread's topic... How do "skeptics" know that they are right? Well, to put it bluntly, sometimes it is just plain old Dunning-Kruger incompetence (or ideological blindness masquerading as incompetence). Check out the latest beverage-through-the-nose piece at WUWT. And don't say that I didn't warn you!!!Moderator Response: [Dikran Marsupial] Oh well, once more unto the breach, dear friends, once more... -
Tom Curtis at 15:26 PM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
William Haas @134: 1) As can be seen above, NH summer insolation was increasing from at least 22 kyr and continued to do so until 12 kyr. That means it was increasing over the period of 20-18.5 kyr we are discussing, as pointed out by Daniel C. 2) Global temperatures rose that period by between 0.2 (Shakun et al) degrees C and 0.4 degrees C (based on scaling the Shakun et al difference to other estimates of the total temperature difference). That is equivalent to year to year variability in temperatures resulting from large tropical volcanoes or strong ENSO events. If such a globally averaged temperature variation is sufficient to trigger so large a change in temperatures over millenium, then the Earth's temperatures would be far more unstable than they are. It is the strong regional and seasonal forcing at a particular location given a particular geographic configuration which is significant in triggering the glacial to interglacial transition - not the weak global effect from 20 kyr to 18.5 kyr. It should also be noted that that 0.2-0.4 degree C increase in temperature includes the full effect of any rapid feedbacks, including the WV feedback. -
william5331 at 14:58 PM on 20 April 2012GISTEMP: Cool or Uncool?
It might be interesting for each of these three sets of data to see what the temperature change has been over the recording period for all the recording stations in 5 degree bands of latitude. Latitude 0 to 5, 5 to 10, 10 to 15 etc. Then we could compare what each of them comes up with for the same band of latitude. -
Tom Curtis at 14:30 PM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
danielc @136, here is figure 3 from Shakun et al, 2012:
The important features for this discussion are the atmospheric CO2 concentration (c), the global temperature (d), and the NH and SH insolation (f). The original caption reads:
"Figure 3 | Global temperature and climate forcings. a, Relative sea level (diamonds). b, Northern Hemisphere ice-sheet area (line) derived from summing the extents of the Laurentide, Cordilleran and Scandinavian (R. Gyllencreutz and J. Mangerud, personal communication) ice sheets through time. c, Atmospheric CO2 concentration. d, Global proxy temperature stack. e, Modelled global temperature stacks from the ALL (blue), CO2 (red) and ORB (green) simulations. Dashed lines show global mean temperatures in the simulations, using sea surface temperatures over ocean and surface air temperatures over land. f, Insolation forcing for latitudes 65o N (purple) and 65o S (orange) at the local summer solstice, and global mean annual insolation (dashed black). Error bars, 1s"
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skywatcher at 13:58 PM on 20 April 2012Roy Spencer finds negative feedback
#1, to make a small addition to the moderator's comment, you have to ask yourself the following question: If Spencer is right, why do a whole range of estimates of climate sensitivity from palaeoclimate observations contradict him? Read Knutti and Hegerl 2008, and the SkS summary here. The thing about palaeoclimate and geological estimate of sensitivity is that they already include the total forcing by clouds and all other factors. Essentially, whenever we estimate climate sensitivity, whether from geological events millions of years ago, from the last glacial maximum, the Holocene, the last century, or recent volcanic eruptions, the results tend to be in the range about 2 to 5C per doubling CO2. If Spencer was right, an awful lot of observational evidence from a lot of different, independent lines of enquiry, quite apart from model data, has to be wrong. Additionally they all have to be wrong in the same direction, by approximately the same amount. Likely? And you'd still have to postulate a mechanism by which we have had glacial and interglacial episodes generated from small Milankovitch forcings. What is much, much more likely is that Spencer is as wrong on this as he has been on quite a number of climate-related matters. -
danielc at 12:07 PM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Here is the image itself:
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danielc at 11:54 AM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@ William Haas #134: The following quote from your post: "What is really missing in this article is a plot of the Milankovitch forcing during the time in question in high enough resolution to make any sense. From the best that I could find, change in solar irradiance caused by orbital cycling peaked in the north roughly a thousand years before the period that we are talking about and was decreasing during this period." Indicates that you did not actually read the article, or if you did, you completely missed the very clear, very simple chart of Milankovitch forcing and solar insolation for 65°N and 65°S from 22 kyr to 8kyr. It's figure 5f in the paper. It very clearly and obviously shows that insolation started from a N. Hemisphere minimum at about 22kyr, and steadily, continuously, and reasonably steeply increased from a value about 2.5% lower than the present insolation at the same latitude to a value nearly 10% greater than the present day at about 12 kyr. Here is another diagram from Berger and Loutre, 1991, via RealClimate... Insolation vs d18O the lowest part of the figure is the NH and SH insolation curve for the time period in question... Stop assuming, and read the paper(s). -
Uncle Ben at 11:50 AM on 20 April 2012Roy Spencer finds negative feedback
I beg to differ. Spencer has simplified his argument and presents it better in his book "The great global warming blunder." I will counter only three of Trenbert's arguments: 1) how Spencer deduces that sensitivity has been exaggerated, not from models, but directly from satellite data; 2) what is a feedback; and 3) what purpose his simple model serves. 1) Sensitivity may be calculated from measurements of radiative energy imbalance dH/dt and sea temperature anomaly dT, both averaged globally. A linear regression of the former vs the latter yields a slope that has been interpreted as the reciprocal of a sensitivity metric. The basis for this method is the assumption that there is not any other significant forcing on the temperature anomaly than the radiative imbalance. The data are considered to be samples of a linear relationship between only two variables plus a large amount of noise. If there were another significant forcing variable x unacknowledged in this process, there would be an error in this method. A change in dT caused by a change in dx would be mistakenly attributed to dH/dt, making dH/dt more powerful a factor than it really is. That is exaggerated sensitivity. Spencer has demonstrated the existence of such a variable. He has connected the data points in the plot described above in the order of their measurement. This converts a set of points into a trajectory. The trajectory typically consists of a repeated alternation between two forms: a messy, loopy curve and a remarkably straight line. That alone strongly suggests two kinds of process which alternate in strength. Spencer interprets this kind of trajectory as an alternation between the slow radiative process of warming the oceans upper layer and the rapid non-radiative process by which the upper layer creates clouds. Candidates for the non-radiative sources of the latter are ocean currents related to ENSO and PDO, which heat or cool the air and moisten or dry it. Clouds created by these sources vary over time in shielding power unpredictably, causing variation of their shading, which creates a radiative forcing. These clouds are not created by contemporaneous solar heating and cooling. More than one forcing? That creates error. It is on the basis of this analysis that Spencer concludes that sensitivity has been exaggerated. 2) Trenbert denies that the second process described above is a forcing. Spencer follows the convention of engineers saying that there is one dependent variable, T, in this system. Feedback is a temperature change caused by a temperature change. Everything else that affects temperature is forcing. Clouds are forcing in this nomenclature. But that is irrelevant. Call it what you will, it exaggerates sensitivity. 3) Spencer's little model is not intended to model the atmosphere of the earth. It is a mini-model that shows that a system of a radiative forcing and a non-radiative forcing creates trajectories of the kind that can be seen in the satellite data, plotted with connections. It is a demonstration of the concept. It is especially useful in that it demonstrates how a simple system with given negative feedback can produce results that appear to involve positive feedback.Moderator Response:[DB] Your #1 merely unsupportedly reiterates Spencer's mantra that clouds cause ENSO. This is not supported by the peer-reviewed literature published in reputable journals.
Your #2 is specious. Climate science is what we are discussing, not engineering.
Your #3 is indeed a demonstration of concept, but one not supported by the literature (as noted above) nor by reality itself.
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Michael Whittemore at 11:35 AM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
I see another post of Haas trying to suggest a little bit of warming in the north is going to cause water vapour to cover the Earth and raise global temperatures. But I guess Tom will just say he is “correct” and this warming seen in the north is part of a “global average”. The simple fact is, water vapour feedback is a local event and the warming only happened in the north, it was not a global forcing at all. Yet lets look at Haas most resent comment below. “if the global average temperature rose than water vapour average values rose […] Therefore during this time an increase in water vapour content would have increased heat retention in the atmosphere” Another fine example of Haas trying to suggest that the warming before the seesaw event was global, and it was caused by water vapour. I think skeptical science is going to have to edit some of their myths if he is “correct” again. -
skywatcher at 09:57 AM on 20 April 2012Return to the Himalayas
Steve Case #44, while you continue to wilfully fail to comprehend four points, there is little more to say: 1: you wilfully seem to fail to understand the concept of reservoirs, and how they modulate water flows between wet seasons (years) and dry seasons (years). Glaciers are natual reservoirs. 2: you wilfully avoid the fact that in some parts of the world, it does not rain at all for many months at a stretch. Below is a climate graph for Dehradun in north India, where the main monsoonal precipitation comes in just two or three months of the year. The other nine or 10 months it is desert dry.
3: you wilfully avoid the possibility that rivers can and do run dry in dry seasons, if there is no continuing supply of water to feed them. Ground water only feeds a river for so long without replenishment. It's not something people living in temperate latitudes are used to, where rain tends to fall all year round to some extent, and so surface runoff and groundwater supplies are regularly replenished. You might want to research intermittent stream, arroyo, wadi, wash, winterbourne, torrente - different names around the world of streams that do not flow all year round.
4: As repeatedly pointed out to you, a warming planet does have increased precipitation, but not everywhere uniformly. It's often a case of The wet get wetter, the dry get drier. Reliability of rainfall is not something to get used to in the future.
If you cannot put these four things together and thus appreciate the value of dry-season glacier runoff for places like northern India, then there is little anyone here can do to help you.
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William Haas at 09:22 AM on 20 April 2012Shakun et al. Clarify the CO2-Temperature Lag
87 Tom Curtis Again thanks for yours and everyone elses efforts. What is really missing in this article is a plot of the Milankovitch forcing during the time in question in high enough resolution to make any sense. From the best that I could find, change in solar irradiance caused by orbital cycling peaked in the north roughly a thousand years before the period that we are talking about and was decreasing during this period. There are those who argue that Milankovitch forcing is not strong enough to do much of anything but I am just going to assume that Milankovitch cycling started the whole thing. Clearly the Milankovitch could have only triggered the climate change but not sustain it because the Milankovitch forcing in the north was decreaseing during the entire 2,500 years but temperatures were increasing. I understand that the orbital cycling did not change the total earth irradiance, just the balance so that Artic summers would have recieved a little more sun light and hence a better oportunity to melt some ice. During this 2.500 year period, according to the article, CO2 levels did not rise but temperatures did rise. According to green house gas theory models, if the global average temperature rose than water vapor average values rose. Water vapor is the green house gas that causes the majoriety of the green house gas heat trapping effect. Therefore during this time an increase in water vapor content would have increased heat retention in the atmosphere which would have caused temperatures to rise even further. If this did not happen then the green house gas effect models that are used today to predict global warming must be incorrect. It is not clear that this water vapor effect had any real effect on climate change. I think that what allowed climate change during this period to be triggered were varations in ocean currents. I think that albedo change and unknowns had some effect but it was ocean currents that caused the the climate to trigger. During the age of the dinasours North and South America were not connected so world ocean currents were much different especially around the equator. It was after North and South America became connected that current ice age cycles began to ocour. The oceans of the world act as a huge non-linear thermal capacitor. We could be looking at some sort of natural frequency of the oceans. Most of the analysis of this data that I have seen does not get much further then simple correlation analysis. I think that work should be done to try to detect phemonenon such as orbital cycles and to compute climate change transfer functions. Who knows what phenomena may be detectable if the appropriate analysis is performed. I do not think that transfer function analysis will be of any value to predict the weather but climate change is a whole different game. No I do not think that water vapor changes alone can cause anything beyond changes in local weather. The climate is not going to spontaneously change because of a chance riae in relative humidity. I do not believe that our climate is inhaently unstable because of green house gas positive feedback and I assume that it has not been modeled as such. -
John Russell at 08:21 AM on 20 April 2012Global Surface Warming Since 1995
In my arguments with them, I think I've see where the average fake sceptic goes wrong with these graphs. The problem seems to me that most of them basically draw a line across the top of all the peaks and then claim there's been no warming. In reality, of course, the peaks represent a only small percentage of the warming going on and it's the bulk of time between the peaks and troughs, when there is a steady but unspectacular rise in average temperatures, that tells the real story. -
scaddenp at 07:50 AM on 20 April 2012Return to the Himalayas
jsk - yes, one of the many expensive options that go into costing adaptation. One question though. Who should pay for these dams? The people dependent on the water, or the people responsible for changing the atmosphere? -
BKsea at 07:26 AM on 20 April 2012Global Surface Warming Since 1995
To me the most egregious misrepresentation of Santer is taking the statement that 17 years of data coverage are needed to compute a trend and then using two individual monthly points separated by 17 years to show no change. These are not even close to the same thing. -
jzk at 07:12 AM on 20 April 2012Return to the Himalayas
Sphaerica @48, Unless humans respond by building reservoirs. -
muoncounter at 06:16 AM on 20 April 2012Return to the Himalayas
Steve Case #47: Nonsense; I make no mention of the 'source.' The source is irrelevant - what matters is that many people derive their freshwater from meltwater-fed rivers. Both references I've posted here and here suggest the same thing: Take away the water impounded as snow and ice and you go thirsty. It would be beneficial to the discussion if you could produce some source material to support your opinions. "Just because a glacier is gone or becomes static, doesn't mean the rain and snow that falls won't continue to flow there." I have no idea what that even means. However, if you are suggesting that glacial meltwater falls as precipitation solely on the same catchment, you are sorely mistaken. Compiled by UNEP's Polar Research Centre GRID-Arendal and experts from research centers in Asia, Europe, Latin America and North America, the report says the larger glaciers may take centuries to disappear but many low-lying, smaller glaciers, which are often crucial water sources in dry lands, are melting much faster. -- emphasis added -
dana1981 at 04:21 AM on 20 April 2012Global Surface Warming Since 1995
Slioch @3 - the question here is whether it's warming, not the causes of that warming. That quote may not be clear, but it's correct.
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