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John Hartz at 05:06 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Suggested reading: “Two Nobelists Offer Views of Human-Driven Global Warming” by Andrew Revkin, DOT Earth, New York Times, Feb 2, 2012 To access this timely and eye-opening article, click here Mario Molina and Burton Richter are the two Nobel Prize winners extensively quoted in this article. -
elsa at 05:05 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Thanks DM vey well said (in both cases!). -
owl905 at 05:04 AM on 4 February 2012Still Going Down the Up Escalator
@dana1981-37. Briggs' knowledge of the terminology is weak and misleading. He's looking for the error bars in the predicted temperatures extrapolated from existing site temperatures. It's basically a chest-puffed crowing revival of 'bad data'/'hockey-stick formulas'/'it's all plastic models'. Turn it over to him and the end result of the time, effort, and money, would probably be 'can't really say'. He deals with mathematical precision, not Large Systems Effects. -
Stephen Baines at 04:47 AM on 4 February 2012Still Going Down the Up Escalator
Frankly, I find all of Biggs talk concerning predictions vs averages and uncertainty beside the point. The point is that uncertainty will not produce a steady incline of the sort observed in the data. Only bias and cherry-picking will. Doesn't matter if your a Bayesian or a frequentist, either. The uncertainty in those data points is implicit in the spread of the data - as is the natural variability which is much larger. Furthermore, if he is a Bayesian, his priors whould include prior information on the likely parameter values given preexisting knowledge about the system state and the physics of CO2. He should do a real analysis with error structures defined etc. I'd bet 10 bucks that once he explcitly isolated sources of error in the data that there would be even stronger evidence for that trend. I think he has the whole thing backwards. Bottom line? Let's see a real analysis rather than word games and obfuscation. -
Dave123 at 04:45 AM on 4 February 2012Still Going Down the Up Escalator
There has been a similar strangeness is the US about this kind of what I can only call a sampling issue. The US constitution requires a decennial census. Despite mathetmatical proof that statistical sampling would overcome known and demonstrated problems in trying to count everyone, Republicans (conservatives) have repeatedly rejected any such modernization attempts (presumably because they fear counting more people not like themeselves). Taking temperatures at separated stations can be described as a statistical sampling of the population of temperatures as opposed to getting 'all' the temperatures. Thus one uses a "model" (extrapolation or interpolation) of sorts to infer that the separated stations do provide information about the space around them. Some of this collapses when you use anomolies instead of temperatures, I think...the rest could be demolished by several experiments (probably available already if one looked) showing that a finer grid didn't change the anomoly in any significant degree. -
DSL at 04:42 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Ugh - wrong link for the last link -- try here or here or, better yet, here. -
Bob Lacatena at 04:41 AM on 4 February 2012Check With Climate Scientists for Views on Climate
79, elsa,...it would be much better to use ocean temperature rather than dress it up as ocean heat content...
Temperature at what depth? The surface? 100m down? 700m down? Maybe the best solution would be to integrate the energy content throughout the entire depth of the ocean. Oh, wait, that's "ocean heat content." Duh.Moderator Response: [Dikran Marsupial] The comment I made regarding elsa's post applies all round. Please can we all keep as cool and collected as possible (whatever the perceived provocation) and avoid escalation. -
DSL at 04:39 AM on 4 February 2012Check With Climate Scientists for Views on Climate
elsa, move it to an appropriate thread. KR has already responded to your disbelief about the power of GCMs. You should move your decadal musings to a thread like this one. I've responded to you there (or will shortly). -
elsa at 04:33 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Composer99, get to the point. Has the world warmed in the last decade or not? If it has not, it would be quite an acceptable position to say that it has not but you continued to believe the trend was upwards. What I find really a bit poor from your side is that you try to hide the fact that it has not warmed but I have found you out. While KR calls me disingenuous I think that word might be better applied to the words used to describe temperature in the past decade by the authors of this article, which could very very easily be misunderstood by the public at large at whom the reply was aimed. A less charitable person might say the text was deliberately misleading. I have not said you should not use other temperature measures apart from land ones, but I have said, elsewhere, that it would be much better to use ocean temperature rather than dress it up as ocean heat content. The ice measure I have criticised elsewhere and it does seem to me very odd to use something as a measure of temperature rather than temperature itself. A model could not possibly show that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean. That is not what any model could do. You could show such a thing by measuring temperatures on the surface and in the deep ocean. You could design a model and see whether its predictions were fulfilled by reality. But by itself a model could not even begin to do so. KR I fail to see how commenting on the precise text of the article could be off topic but no doubt you can explain. As I have explained I have focussed on a ten year period here and in the previous article because that is what the articles talked about. The time period was the authors' choice not mine. Since you accuse me of being disingenuous let us have your plain view on the question: did the world get warmer in the last decade? Don't hide behind the smart phrases of this article and don't go on about how 10 years may not be representative (which incidentally I accept). Just tell us what you think the facts of the temperature record are for the last decade.Moderator Response: [Dikran Marsupial] Please can everybody moderate the tone of this discussion? We are here to discuss the science, and that is not best served by ill-mannered, aggressive tone or over-confidence in ones own ability. Generally it is wise if you think there is a discrepancy or contradiction in the views of leading climatologists, then it is just possible that the miunderstanding lies with you, rather than with them. -
Check With Climate Scientists for Views on Climate
elsa - I have responded to your off-topic model comments here, on the Models Are Unreliable thread. If you have additional issues with models, please take it there. On this thread, and on the previous measurements versus newspapers thread, your comments continue to focus on 10 year periods, in an apparent attempt to excuse claims made on those periods. The purposes of these threads is to point out that 10 years is insufficient time to make a trend determination, that pauses and jumps of up to decadal duration are to be expected, and that claims about short term trends being significant are really quite unsupportable. And in fact that "Climate experts know that the long-term warming trend has not abated in the past decade". I have to say that your comments are, by now, quite disingenuous. -
Composer99 at 03:44 AM on 4 February 2012Check With Climate Scientists for Views on Climate
elsa: (1) The reason why the last decade is of any focus whatsoever, apart from the fact it is the warmest decade in the modern instrumental record, is because it is the focus of denialist attacks on climate science. Over and over one sees claims such as "global warming stopped in 1998" or equivalent. The fact of the matter is that when you take into account the other factors which affect global surface temperatures, most importantly solar activity, ENSO, and volcanic activity, the warming is continuing unabated over the 'noughts and into the 'tens of this century. That is what Foster & Rahmstorf 2011 [apologies if I have misspelled any names] has done. A link to their paper is easily found on this site. The other fact of the matter is that when the denialists are making claims such as "warming is flat/it's cooled this decade" or other such nonsense, they are playing statistical & semantic games rather than coming to grips with the physics involved. You yourself appear to be guilty of this fallacy in suggesting previously that we should ignore things like ice melt & ocean heat content measurements in favour of land surface temperatures, even though this would be ignoring the basic physics involved. (2) The OP is a letter submitted to the WSJ and not itself a scientific publication. If you stick solely with this article I can see why you would get the impression that this is all a "he said-she said" argument. If you actually go check out the evidence you'll find it's anything but. The scientists posting the letter in the OP have the weight of massive amounts of converging evidence behind their statements. The scientists who posted the denialist editorial do not. (3) You state: "They then go on to say "computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean." That statement, as I pointed out yesterday cannot be true. It is not within the power of a model to do such a thing." Please provide substantiation for this final point of yours. One can both measure and model the flow of thermal energy throughout the Earth system (for ocean vs land & ice heat content see, for example, Church 2011). This thermal energy is what is causing surface temperatures to rise, ice to melt, and the ocean to heat up. Asserting what models can or cannot do without a reference to back up your claim is an argument from ignorance, and IMO if no one has bothered to reply to it it is because it is without merit to begin with. -
Models are unreliable
elsa - Redirecting from an off-topic comment on another thread: "They then go on to say "computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean." To be clear on this, global circulation models incorporating the most accurate physics we have on atmospheric and oceanic circulation under various forcing conditions exhibit behaviors including decade long very low or very steep atmospheric warming, with the inverse generally showing in deep ocean regions. This is entirely consistent with observations of climate behavior under, for example, ENSO extremes (El Nino, La Nina cycles). "That statement, as I pointed out yesterday cannot be true. It is not within the power of a model to do such a thing." And here you would be incorrect. -
Esop at 03:36 AM on 4 February 2012Check With Climate Scientists for Views on Climate
#73: That is a good point. Ice free Arctic, possible before 2020 could easily be a natural oscillation like ENSO, but with a frequency of approx. 125,000 years (last time we know for certain that the Arctic was ice free). That it happens right now when we are pumping 90 million tons of a heat trapping gas into the atmosphere every single day of the week probably has nothing to do with it. -
dana1981 at 03:19 AM on 4 February 2012Still Going Down the Up Escalator
Dikran @36 - yes, the final 2 BEST data points are only based on ~40 Antarctic temperature stations. As you note and as noted in the post above, the uncertainty on the monthly anomaly data is in the ballpark of 0.05 to 0.1°C in recent years, with the exception of those two incomplete data points. -
dana1981 at 03:16 AM on 4 February 2012Still Going Down the Up Escalator
I'm reminded here of economist Paul Krugman's "very important people" (VIPs), who are individuals that have made very wrong claims about economics, but who are held in high regard, and thus their opinions are taken seriously. When it's demonstrated that their statements make no sense, the VIP defenders say "you must be misunderstanding their arguments, because they wouldn't say something that makes no sense." It certainly appears to me that Briggs' arguments on this matter simply don't make any sense. I suspect it's because, as Dikran has noted, he has not bothered to understand basic climate science concepts before trying to analyze the data. His 'prediction uncertainty' also seems like nonsense, because as discussed in the post above, the groups putting together the global surface temperature estimates include uncertainty ranges, which are not even remotely as large as Briggs suggests. -
Dikran Marsupial at 03:15 AM on 4 February 2012Still Going Down the Up Escalator
apeescape If you look at the uncertainties for the monthly anomaly estimates in the BEST dataset, the last two months in the dataset have uncertainties of 2.763 and 2.928, however the average for the preceding decade is only 0.096375. ISTR that there is problem (very few stations?) with the last two entries in the BEST data, hence the large uncertainties. I'd say that Briggs is rather overstating the uncertainties somewhat! -
elsa at 03:15 AM on 4 February 2012Check With Climate Scientists for Views on Climate
The only fact about climate that was discussed in this article related to the last decade. That is why I focussed on that period. I know some peole have commented that I was not being very rigourous in my approach using only ten years and I accept that, my point was this was what was under discussion here. I have also tried to stick to information given in the article rather than look elsewhere as otherwise you end up with a monster subject to discuss. Someone pointed me to an interactive site and told me to go check out the numbers. I did and lo and behold I could not see any warming in the period. I then asked myself just how the reply to the "deniers" set out in this article could make out that there was warming given that was not what the graphs showed. Perhaps they were using a different series. But then I took a closer look at what they actually say, which is "Climate experts know that the long-term warming trend has not abated in the past decade." So actually they do not quite say the planet warmed in the past decade, but by looking at the careful wording you can see how both sides could be right. The world may not have warmed in the decade but the warming trend has not abated. It would be intersting to know if these scientists actually think the world got warmer in the last decade as opposed to sidestepping the issue with a smart piece of wording. They then go on to say "computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean." That statement, as I pointed out yesterday cannot be true. It is not within the power of a model to do such a thing. While there has been a great deal of comment about other points I have made no-one has responded to this point at all. Anybody care to do so? -
Dikran Marsupial at 03:07 AM on 4 February 2012Still Going Down the Up Escalator
In case anyone is interested, I just computed the credible interval for the (Bayesian) linear regression for the last decade of sensible values in the BEST monthly anomalies (March 2000 to March 2010)
As you can see a horizontal(ish) line just about fits into the credible interval, but the bulk of the credible interval suggests we can be confident that there has been some warming. When I get a moment I'll include the uncertainties in the estimates of the anomalies and see if it makes much of a difference.
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Bert from Eltham at 02:54 AM on 4 February 2012Still Going Down the Up Escalator
I did not know where to ask but Nikolov and Zeller have managed to really con? the denialist blogosphere with a very strange theory. After wading through the usual partially true glib rubbish. We seem to have a paradigm shift of biblical proportions. Please delete this if it is out of turn. My analysis is that it is a complete hoax or just another delusion? Bert -
Fitz1309 at 02:44 AM on 4 February 2012Monckton Myth #17: Debate vs. Denniss, Part 1
I assume you've seen that Monckton has replied to this article on WUWT: http://wattsupwiththat.com/2012/02/03/monckton-responds-to-skeptical-science/#comment-883497 -
John Hartz at 02:18 AM on 4 February 2012Measurements show Earth heating up, think tanks & newspapers disagree
The two “’Skeptics’ guide to global warming” graphics contained in MarkR’s original post are featured in: “How to cherry-pick your 'Global warming has stopped' argument - in pictures” by Robin Webster, The Carbon Brief, Feb 3, 2012. To access this in-depth article, click here. PS: Kudos to MakR on your creativity. -
apeescape at 02:14 AM on 4 February 2012Still Going Down the Up Escalator
Some on Briggs's blog are saying that the observation / averaging uncertainty is around +/- 2.5C. I mean, if it's that big, you'll most likely see it in the data itself. Briggs himself says you can't distinguish between 1940s and 2000s temps, but even in this case, you'll use the decadal average to test the null -- which in turn, make it easier to reject than comparing single year data. Given that thermometers are pretty damn good way of measuring temps, and different averaging methods get really similar results (especially for recent data), I think he is concocting his own uncertainty monster. I'm still confused about the prediction interval of the global average... the global average is what we want to compare... -
Still Going Down the Up Escalator
RobertS - "The planet is not perfectly sampled at every point on its surface, so in creating an average global temperature, you're attempting to "predict" the temperature at unsampled points using data from sampled points." Um, _no_. That is estimation, not prediction. A prediction is a statement about what will happen in the future, possibly conditionally dependent upon various alternatives, while an estimation is an approximate calculation of measurements in the face of uncertainty or subsampling. Briggs conflation of the two indicates either a need for a dictionary in his reference materials or perhaps an attempt to cast temperature estimations as models so that he could take advantage of the 'skeptic' disdain for models in general. -
Ken Lambert at 01:36 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Thank you Daniel. To get specifically on topic - Perhaps Dr Trenberth could explain his fundamental disagreement with Dr Hansen about the magnitude of the warming imbalance and why he does not believe Dr Hansen's 'Chinese aerosols' explanation 'for a minute'. -
Ken Lambert at 01:27 AM on 4 February 2012Check With Climate Scientists for Views on Climate
Norman et al: 90% of the planet's ice is in Antarctica - the portion in the Arctic when all other land ice is deducted is pretty small. The Arctic is subject to wide variations in sea ice extent due to transport of heat from lower latitudes and its relatively small volume. Not much is know about Arctic sea ice extent further back than 100 years or so. Transport of heat by currents to the Arctic can be, but is not necessarily an AGW indicator - it could simply be an internal re-distribution of planetary heat similar to ENSO.Response:[DB] Please find a more appropriate thread for this discussion. The topic of this thread is Check With Climate Scientists for Views on Climate.
The discussion that you and Norman are pursuing is off-topic for this thread.
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MangoChutney at 01:18 AM on 4 February 2012Monckton Myth #17: Debate vs. Denniss, Part 2
Monctons response is here: http://wattsupwiththat.com/2012/02/03/monckton-responds-to-skeptical-science/ -
Paul from VA at 01:17 AM on 4 February 2012Still Going Down the Up Escalator
@Spherica, CBDunkerson True, satellites still are not a 100% perfect sampling, but the entirety of Earth's surface is sampled below a latitude of ~80 deg. While not every single point is measured at infinite resolution, the temperature of every single point combined with its nearest neighbors is, which means that no extrapolation to unsampled areas is necessary to get a global temperature average except at the very poles. Also, I'm not surprised at the result (more going up the down escalator!), but now the pseudo-skeptics can't claim that we're cherry-picking GISS temp because it's warmer or some other such bogus argument..... -
heijdensejan at 01:02 AM on 4 February 2012It's cooling
Roy Spencer today reported that the temperature is -0.09 C below (?) what he does not tell is that in 2010 the line 0 was about 0.1 degree lower then it is now http://friendsofginandtonic.org/files/5a90411e58ea05ba14e986929b1074d4-1.html, you move up the baseline and then you tell the earth is cooling.... -
peterthorne at 00:47 AM on 4 February 2012Still Going Down the Up Escalator
Sorry, Santer et al., 2011 -
peterthorne at 00:47 AM on 4 February 2012Still Going Down the Up Escalator
Scientifically, the point really is that the short term trend is not a good indicator of the long-term forced change component of climate. Natural variability is dominant on the decadal timescale as documented in Knight et al., 2010, Easterling and Wehner, 2009 (10?) and Santer et al, 2001. I think your point may be more powerful by showing the opposite escalator too - one where each of the short segments shows much greater rate of warming than the long-term. That is less likely to lead to accusations of partisanship and is making the scientific point more forcibly - that short term trends can be used to indicate anything by any vested interest. Have you tried making such a "running up the up escalator" graph? It would be very interesting to see and I think help strengthen the point and avoid gross partisanship accusations.Response:[dana1981] Thanks for your feedback, Dr. Thorne. The purpose of The Escalator is to show how 'skeptics' and realists actually view global temperatures. 'Skeptics' constantly look for flattening or cooling trends in short-term data, whereas realists (by definition) don't look for rapid warming trends in short-term data, but rather examine long-term trends.
However, your point is taken that we could do a 'running up the escalator' graph to show that short-term data can be manipulated in the opposite way, as opposed to the way it's actually manipulated, which is what the current Escalator shows. We'll take this suggestion under consideration.
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Bob Lacatena at 00:44 AM on 4 February 2012Still Going Down the Up Escalator
25, Paul, I was able to get an ending downward trend for the RSS data, thanks to the recent La Niña and by selecting 2002 as a start date.
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Bob Lacatena at 00:07 AM on 4 February 2012Still Going Down the Up Escalator
25, Paul, You are very right, but for the wrong reasons. It is much harder to generate negative trends from the UAH data (I didn't try RSS). The tropospheric data is much cleaner, not so much because of the global sampling (it's not global, BTW, it reaches far towards the poles but does miss them -- see the gray areas on the RSS images here – the satellite orbits used are not set up to give a good, downward looking view of the earth at the poles), I think, but because the warming is less impacted by noise. In fact, I couldn't create a negative trend up to the end with the UAH data. Maybe someone else can try. You have to sit and peck around for exactly the rightcherry flavoredend points to use. It's very hard to do what with all of the consistent and unequivocal warming that's occurred in the past fifteen years.
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CBDunkerson at 00:00 AM on 4 February 2012Still Going Down the Up Escalator
Paul, actually the satellite data just uses a grid with smaller cells. It is impossible to 'completely sample the Earth's surface'. Think about it. You'd need the equivalent of a 'thermometer' measuring the 'temperature' of each individual atom... or each sub-atomic particle within each atom. Anything less than that is inherently an average of multiple sources... i.e. all 'temperature' readings are averages. That said, it would certainly be possible to construct an 'escalator' for the satellite temperature record(s). However, it would likely only have a few steps since the satellite record is comparatively short. -
Paul from VA at 23:36 PM on 3 February 2012Still Going Down the Up Escalator
Just curious, what does the escalator graphic look like for the satellite temperature series? While I'm exceptionally well-aware of the troubles in calibrating the satellite data, it seems that the satellite temperature series could utterly destroy the sampling uncertainty argument, as it completely samples the Earth's surface..... -
Dikran Marsupial at 23:31 PM on 3 February 2012Still Going Down the Up Escalator
Tom Curtis I have been contributing to Briggs blog, and it seems to me he fundamentally doesn't understand the climatological issues, and apparently doesn't want to, e.g. As interesting and useful of discussions of forced versus unforced “variability” are, they are irrelevant utterly to whether claims (A) and (B) are true. It matters not how the data arose to answer the claims of whether the temperature is higher or lower over the last decade. However claims A and B relate to the statement The lack of warming for more than a decade—indeed, the smaller-than-predicted warming over the 22 years since the U.N.’s Intergovernmental Panel on Climate Change (IPCC) began issuing projections—suggests that computer models have greatly exaggerated how much warming additional CO2 can cause. and the amount of additional warming that CO2 can cause is concerned with the forced component and only the forced component. The key to success in statistics is a willingness to immerse yourself in the data and understand the data generating process and the purpose of the study. If you just wade in thinking you know what is important and what isn't and not listening to those who know the data, it is a recipe for disaster. Well I did try... -
CBDunkerson at 23:24 PM on 3 February 2012Check With Climate Scientists for Views on Climate
Norman wrote: "The air temperature in this area is not what is keeping the water around the island liquid, it would be warmer water moving in keeping the surface above freezing as the link muoncounter provided did state." You say that with far more authority than it deserves. Surely increased air and water temperatures would both contribute to lower ice formation, no? To quote the NSIDC section under discussion: "Air temperatures in December were lower than average over much of the Arctic Ocean, but higher than average over the Kara and Barents seas. Higher-than-average temperatures in these regions stemmed from two major factors. First, where sea ice extent is low, heat can escape from areas of open water, warming the atmosphere. Second, surface winds in the Kara and Barents Sea ice blew persistently from the south, bringing in heat from lower latitudes. This imported heat also helped to keep sea ice extent low in this area." So, no... your claim that this text states that warm water is the cause is false. That is one of two factors they cite. The other being warm air blown in from the south. Shocking. Heat import counters ice formation... regardless of whether the heat is brought in by air or water. That should be wholly uncontroversial. And all that being said, going back to muoncounter's original statement we find: "While you're at it, consider Arctic ice melt and world glacier mass loss; explain how these symptoms can possibly be happening if there's been no warming." So how does arguing that the ice melt is entirely due to water warming (rather than both air and water) 'contradict' his statement that it is due to warming? You seem to be 'disagreeing' with his point by saying things which prove it.Response:[DB] Please take this discussion to a more appropriate thread. Thanks!
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Tom Curtis at 23:11 PM on 3 February 2012Still Going Down the Up Escalator
Dikran @22, there is considerable doubt as to what Briggs claim is under different circumstances, but in the blog from which the graph @14 comes, he is talking about using one value (New Proxy) to predict another value (Temperature). While deriving the regression line is an important step in that process, the regression line is not what is being predicted. What is being predicted is temperature, given the value of the "new proxy". Therefore, he has either described the error margins of the regression as the "prediction interval" which is simply false, or if your conjecture is incorrect, he has not properly calculated the error margins at all (as shown by the fact that less than 25% of the data used in calculating the regression (and hence the prediction) falls within the "prediction interval". In either case he has made an error, and his argument that classical statistics underestimates errors is based firmly on the consequences of that mistake. This goes directly to RobertS's defense of Briggs. In essence that defense is that Brigg's has been misunderstood because he has been precise. This example shows that the mere use of technical language does not make what you say precise, let alone accurate. If Briggs has been misunderstood, it is because he has been unclear, not because he has been precise. -
Norman at 23:06 PM on 3 February 2012Check With Climate Scientists for Views on Climate
owl905 @70, Here is a link to the January 2012 temp for Novaya Zemlya (land in area where Barents sea ice is still liquid). You are correct that area was very warm for its normal temp, but it has been below freezing temps since January 14th. January temps town on Novaya Zemlya. The air temperature in this area is not what is keeping the water around the island liquid, it would be warmer water moving in keeping the surface above freezing as the link muoncounter provided did state.Response:[DB] You have already been warned about dragging yet another thread off-topic about anecdotal weather events. Desist.
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Dikran Marsupial at 22:52 PM on 3 February 2012Still Going Down the Up Escalator
Tom Curtis as I said his writing isn't the clearest, I was just opting for the most likely explanation of what he actually meant. I think it would be a good idea to include the dark area on plots of regression lines (I'd plot the most likely line as well) as it would show very clearly that the trend estimate for short timescales were very uncertain. This would prevent skeptics from claiming that the trend was flat as the error bars would show that they could be flat, or cooling or warming, and there isn't enough data to decide which. Which error bars you choose depends on whether you are trying to predict the observations or trying to estimate the rate of warming. In this case it is the latter. -
Tom Curtis at 22:45 PM on 3 February 2012Still Going Down the Up Escalator
Dikran Marsupial @20, thank you. That explanation makes sense, but is contradicted by Briggs claim that:"Notice that most of the old data points lie within the Bayesian interval—as we would hope they would—but very few of them lie within the classical parameter interval."
We do not expect all the data to fall on the regression line, and there is no reason why it should. Failure of the data to fall within the error bars of the regression line is therefore, irrelevant, contrary to Briggs' claim. I remain uncertain as to whether Briggs is confusing the error of the "predicted" regression line with the error of the predicted data, or is simply hopelessly confusing in his discussion. However, it is not a good model for to great a confidence in temperature indices in that the confidence intervals shown for temperature indices are for the value, not for the regression. Hence absent good reason to think otherwise I shall disregard that blog as irrelevant. -
Dikran Marsupial at 22:33 PM on 3 February 2012Still Going Down the Up Escalator
Tom The dark band is a credible interval for the regression line, not for the observations themselves. It is basically saying that with 95% probability the "true" regression line lies in that interval. The credible interval for the observations themselves is a combination of the credible interval for the regression line, plus a component due to the noise in the data (i.e. the spread of data around the regression line). I am not surprised that this misunderstanding should ocurr, Briggs' articles seem rather ambiguous and opaque from what I have read so far. -
Dikran Marsupial at 22:27 PM on 3 February 2012Still Going Down the Up Escalator
RobertS wrote "And Briggs never "backpedaled." He's remained consistent in his description of averages as models. " which made me think of this:
Note I am not saying that Briggs is a screw-up (he isn't), merely that being consistent in promulgating an incorrect argument is not necessarily a good thing.
His point seems to be about including the uncertainty in computing the global mean temperature into computing the error bars on the trend is perfectly reasonable. However what he should have done is first demonstrate that it makes a meaningful difference to the conclusion, rather than just hint that it might to spread baseless uncertainty (the uncertainty in computing the means looks pretty small to me compared to the uncertainty in the trend due to weather noise - is internal climate variability)
As the regression line is not being used to predict or extrapolate the temperature anywhere, the "prediction" uncertainty is irrelevant.
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michael sweet at 22:05 PM on 3 February 2012Still Going Down the Up Escalator
Robert, Your post was deleted as trolling, perhaps this one will be also. Averaging results as described in published papers is not predicting. You claim that in order to know something we must measure it perfectly everywhere. If that were true, then nothing can be measured. Every measurement is an average of several others. You also asked for the error bars which are linked in the OP. If you cannot bother to read the OP, why comment? A brief glance at the error bars shows that the error is much less than the trend. No analysis is needed for such an obvious observation. Briggs is wrong about the error also. It is common to leave off the error bars to make the graph more readable for a general audience. Briggs is trying to artificially manufacture doubt -
Tom Curtis at 22:00 PM on 3 February 2012Still Going Down the Up Escalator
RobertS @16, if what you say is correct, then the gist of Briggs critique is that he does not know, or chooses to ignore the meaning of the word "index", as in the "GISTEMP Land/Ocean Temperature Index" or the "BEST Land Temperature Index". They are called indices because we do not mistake them for the thing itself. Suggesting the indices have insufficiently quantified the error because the they are presumed to be the thing itself simply shows incomprehension of what is being done. -
RobertS at 21:52 PM on 3 February 2012Still Going Down the Up Escalator
Tom, I'm not sure what Briggs' thinking was, but DC does indeed provide a convincing rebuttal to that point. Despite what you appear to think, I don't believe Briggs to be the Second Coming, and I won't attempt to defend every statement he has made. But many of the criticisms leveled at him over the past few days come from a simple lack of understanding of precisely what he is saying. In particular, Tamino's entire critique revolves around the idea that Briggs is simply using the words "model" and "prediction" as some sort of semantics ploy in an effort to evoke the instinctual rejection by denialists of any argument which contain those things. This is not true. The planet is not perfectly sampled at every point on its surface, so in creating an average global temperature, you're attempting to "predict" the temperature at unsampled points using data from sampled points. These "predictions" result in uncertainty in the end product, which Briggs alleges is only properly accounted for under Bayes theorem. He fleshes this process out in more detail in the second link I give above. Such terminology is fairly common in certain fields, but not in others. Michael, I had written a response to you earlier, but it disappeared. Let's try again: What exactly do you mean by measured results? Can we measure the temperature at every point on the Earth's surface? If no, how can we combine the data we do have to create a coherent record of global temperature? Is this method completely without error? -
CBDunkerson at 21:47 PM on 3 February 2012Still Going Down the Up Escalator
RobertS, how is it correct to call 'averages' (which is not an accurate description either) of temperature measurements "predictions"? Or are you going to pull another semantic absurdity and claim that when Briggs says 'predictions', what he really means is 'measurements'? If the man was using any of the commonly accepted meanings of these words then what he said is flat out wrong. If he wasn't then there really isn't any way to tell what he was actually saying. In any event, if any part of what Briggs said were true it would ironically also contradict all of the 'no warming since XyZ' claims... because those are all based on the 'model predictions' (aka, thermometer measurements) Briggs is saying can't be used that way. Indeed, he is claiming that the entire ~130 year period is too short to establish a trend line... so 10 years would just be pathetic. -
Tom Curtis at 21:42 PM on 3 February 2012Still Going Down the Up Escalator
RobertS @9, I am still working my way through the discussions you link to, but one thing has caught my attention. Specifically, in the second blog by Briggs to which you link, he shows the following graph:
Briggs says of the dark grey band that it is "...the classical parametric prediction interval for these new proxy measurements." Earlier he had mentioned that, "The 95% parametric prediction interval for this model happens to be 17.6oC to 20.4oC." Ergo the "prediction interval" shown is the 95% prediction interval, ie, the interval inside which we would expect 95% of values to fall.
The problem is, in the graph shown, just 22.6% (7 of 31) of observed values fall within the 95% prediction interval. How is it possible for a measure of the 95% prediction interval fail to include close to 95% of the data from which the prediction interval is calculated? To my mind that only 22.6% the data from which the 95% prediction interval is derived falls inside the 95% prediction interval seems like a contradiction in terms.
On the face of it, Briggs has simply miscalculated the 95% prediction interval. His calculated prediction interval performs so badly because it is simply the wrong interval. And given that, he is able to show his calculated interval radically underestimates uncertainty simply because his error causes it to radically underestimate the uncertainty.
I am interested in hearing why we should trust a statistician who makes so fundamental error (if he has); or alternatively just why statisticians so distort the language that a 95% prediction interval means (as it must if Briggs has made no error) that interval in which approx 25% of the data will fall.
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Tom Curtis at 21:08 PM on 3 February 2012Still Going Down the Up Escalator
RobertS @12, Briggs included in his critique the claim that:"Notice old Phil (his source, actually) starts, quite arbitrarily, with 1973, a point which is lower than the years preceding this date."
To this DeepClimate responded at Open Mind:"For greater certainty here are the BEST annual values for 1970s with trend slope to 2009: Year Anom Trend to 2009 1970 0.070 0.271 1971 -0.042 0.277 1972 -0.137 0.277 1973 0.386 0.273 1974 -0.130 0.290 1975 0.166 0.284 1976 -0.213 0.291 1977 0.274 0.276 1978 0.104 0.286 1979 0.023 0.284 So Briggs has got this completely wrong."
That seems to me sufficient rebutal, but Briggs was "consistent", and wrote,"Deep Climate–try this from the 1940s."
So DeepClimate did:"Well, OK: 1940 0.165 1941 0.087 1942 0.084 1943 0.160 1944 0.255 1945 -0.042 1946 0.022 1947 0.165 1948 0.103 1949 -0.044 1973 is still not lower than any of those (and neither is it lower than any year in the 1950s and 1960s). Want to try again? Let me save you the trouble. It turns out 1973 is *higher* than every single year preceding it. So you were utterly, completely wrong."
This may seem like a trivial matter, but accusations of cherry-picking, even veiled accusations, are not trivial. It is relevant in this case, however, because it shows that Briggs "consistency" is in significant degree merely the inability to admit error. Don't pretend otherwise when the disproof is so straightforward. -
RobertS at 20:53 PM on 3 February 2012Still Going Down the Up Escalator
Yes, a common tactic with fake-skeptics Consistency is also a common tactic with people who are correct. Who'd have thunk it? -
Rob Painting at 20:35 PM on 3 February 2012Still Going Down the Up Escalator
And Briggs never "backpedaled." He's remained consistent in his description of averages as models Yes, a common tactic with fake-skeptics - no matter how ridiculous their assertion is, they never admit they are wrong. No claim is too ridiculous to be defended by them it seems.
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