tag:blogger.com,1999:blog-8216971263350849959.post2157439650736228350..comments2023-08-07T16:41:49.660+02:00Comments on Die Klimazwiebel: Temperature hiatus updateeduardohttp://www.blogger.com/profile/17725131974182980651noreply@blogger.comBlogger48125tag:blogger.com,1999:blog-8216971263350849959.post-40618361177929437142014-02-11T00:01:51.864+01:002014-02-11T00:01:51.864+01:00Part 2
If you believe that the decadal internal va...Part 2<br /><i>If you believe that the decadal internal variability is misrepresented by the models, then you cannot believe in the 'detection of climate change'</i><br />Good point. I did not say "misrepresented". What I mean is that to my knowledge the physical processes relevant for decadal variability are not well understood and that we still suck at even scratching the potential predictability. Correct me if I am wrong, this field seems moving fast now. I have good reasons to believe that detection studies such as optimal fingerprinting are meaningful and deliver robust results anyways. These reasons are 1) that other sources than model simulations contain information about internal variability (paleorecords, obsdata) that help to constrain estimates of its magnitude, their problems (time-resolution, ext. forcing, short records ..) notwithstanding. Much more importantly is 2) that the sensibility of attributions studies to estimates of nat. variability can be and has been examined and the results reinforce the validity of the attribution studies.<br /><br />All this I <b>believe</b> as I can't possibly read, understand and evaluate (let alone reproduce) the science involved. I believe this, because my little personal experience supports the idea that the huge bulk of researchers have an attitude as demanded by this tradition called "science", which results in, broadly speaking, me trusting other people's write-up. Hans von Storch calls for vigilance against letting politics (or other forces) taint scientific work and/or presentation because science might loose the trust of the public and become "un-sustainable". I'd like to state that much more dangerous, really existential and the quickest way to irrelevance for science is not the loss of some authority granted by the general public, but rather the loss of trust of the researchers themselves into the functioning of their own tradition and into a majority of peers that shares an attitude and the ethics which will let the good stuff float atop, in due course.<br /><br />An excellent starting point to start practicing this vigilance is the interpretation of statistical results, in particular when the epistemological power of hypothesis tests, as applied to controlled experiments, is falsely ascribed to the statistical analysis of observational studies.hvwnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-4236872976074693372014-02-11T00:00:38.242+01:002014-02-11T00:00:38.242+01:00Eduardo, #43
ok, I understand what you mean.
Tha...Eduardo, #43<br /><br /><i>ok, I understand what you mean. </i><br />Thanks!<br /><br /><i>The IPCCc 'test' was also conducted a posteriori, yet it has been presented as a proof that the 1980-1998 trend is very likely anthropogenic. </i><br />Yes, I would consider such an argument invalid. Are you sure the IPCC has put that forward?<br /><br /><i>...Well, I think it does, but of course you are entitled to your opinion</i><br />Sorry, that was a bit harsh. Let's put it like that: My perception about the value of this exercise dropped more than usual, between reading the abstract and really thinking it through. The abstract reads:<br /><br /><i>...we find that the continued warming stagnation over fifteen years, from 1998 -2012, is no longer consistent with model projections even at the 2% confidence level.</i><br /><br />This language clearly implies a confidence interval and a hypothesis test. Yes, the caveats are duly mentioned in the "Supplementary text", but no interpretation is given how this violation of the "fundamental sampling assumption" should be interpreted. The reader will think "Ok, some practically not relevant assumption violated, happens, I remember the 2% probability though, what else?<br /><br />Good that Hans von Storch was quoted far and wide, directly and indirectly, saying: "A trend, which we believe happens rarely in real climate, but really have no clue, showed up in our climate simulations only rarely".<br /><br />Oh, wait.<br /><br />Actually he said something entirely different, but equally correct.<br /><br />If there was no politicisation of climate science, no "skeptics" induced media attention to the "hiatus", you would have done that calculation, no question. But would you have written it up so nicely, submitted it to Nature, written blog-posts and updates about the impact of one more datapoint? I guess not. This exercise has been oversold.<br /><br />Continued ...<br />hvwnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-38109353448770858042014-02-04T21:28:27.321+01:002014-02-04T21:28:27.321+01:00hvw
Sure, the aim was different. And I had a diff...hvw<br /><br />Sure, the aim was different. And I had a different author in mind, Tamsin (not Tamino --sorry if you read this!). She has an interesting blog:<br /><br />http://blogs.plos.org/models/<br /><br />@ReinerGrundmannhttps://www.blogger.com/profile/12759452975366986236noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-35868961868884860152014-02-03T20:08:13.374+01:002014-02-03T20:08:13.374+01:00"Nach allem was wir bösen zweifelnden Laien l...<i>"Nach allem was wir bösen zweifelnden Laien lesen mussten von seitens eines Georg H. z.B. oder eines Stefan R. und unzähliger Andreasse muss man sich schon sehr zurückhalten um nicht in schallendes Gelächter auszubrechen."</i><br /><br />Hallo Yeph,<br /><br />z.B. worüber?<br /><br />MfG<br />S.HaderS.Hadernoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-40605987159958684652014-02-02T12:10:45.232+01:002014-02-02T12:10:45.232+01:00@Andreas"
Sie schreiben:
"Mit "dü...@Andreas"<br /><br />Sie schreiben:<br /><br />"Mit "dünnhäutig" meine ich z.B., dass Sie "cherry picking" ansprachen, so, als müssten Sie sich gegen diesen Vorwurf verteidigen (den niemand erhoben hat). Für mich beinhaltet "cherry picking" die Absicht, mit Tricks zu täuschen, daher habe ich nie diesen Begriff hier benutzt. Es ging doch nie um ihre Person oder gar ihre Integrität, sondern einzig um die Frage, ob man die Argumentation im Sinne eines Hypothesentests benutzen kann."<br /><br />Sorry im Voraus!<br /><br />Aber, dies ist wohl ein schlechter Witz?!<br /><br />Cherry-Picking? <br /><br />Die letzten 15 Jahre? 30 Jahre? 115 Jahre? Nach allem was wir bösen zweifelnden Laien lesen mussten von seitens eines Georg H. z.B. oder eines Stefan R. und unzähliger Andreasse muss man sich schon sehr zurückhalten um nicht in schallendes Gelächter auszubrechen.<br /><br />Solange der "hiatus" anhält ist es so wie Eduardo es hier erklärt. Das versteht sogar jedes Kind.<br /><br />"Science at it's least" würde ich das nennen, lieber freundlicher Andreas, der ja eigentlich gar nichts sagen wollte.<br /><br />Und der Spaß fängt ja gerade erst an. :-)<br /><br />Yeph <br /> Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-50710298644551919972014-02-01T18:22:20.511+01:002014-02-01T18:22:20.511+01:00@ 37
hvv,
ok, I understand what you mean.
Sue, ...@ 37<br />hvv,<br /><br />ok, I understand what you mean. <br /><br />Sue, the possibility that the observed trend comes from the model distribution is always there, and we just had hit an an event that lies below the 2% percentile. This is why one should compare two samples, one from the models and one from observations, but unfortunately we do not have a sample large enough from observations.<br /><br />This being said, however, the same argument could be made to the reasoning of the IPCC that Georg suggested above: the period 1980-1998 the model ensemble driven by natural forcings only had a lot of problems simulating the observed trend. perhaps it was a rare event , above the 999% percentile ? I do not see a logical difference between both situations. The IPCCc 'test' was also conducted a posteriori, yet it has been presented as a proof that the 1980-1998 trend is very likely anthropogenic. <br /><br />'His confusion seemed to stem from the very issues we were discussing in the following, not from failure to get the basic idea of a statistical test.'<br /><br />Then I should have explained in another way. It is difficult to know before hand though.<br /><br />'I believe too that "something important is missing in the models". Particularly with respect to the representation of decadal variability. I am afraid that your calculation doesn't contribute to that belief '<br /><br />Well, I think it does, but of course you are entitled to your opinion. I am not sure whether the spread of model trends for different time segments was that well known, although it is easy to calculate it. Actually, nobody seemed to be very much interested on that spread until the hiatus appeared. <br />If you believe that the decadal internal variability is misrepresented by the models, then you cannot believe in the 'detection of climate change' as this detection is based on estimations of internal variability from models. At least there is an unquantifiable uncertainty there.eduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-17480879280683391912014-01-31T22:51:41.637+01:002014-01-31T22:51:41.637+01:00@ hvw
Danke (s. #37). Sie haben mich sofort verst...@ hvw<br /><br />Danke (s. #37). Sie haben mich sofort verstanden, können es aber viel präziser formulieren.<br /><br /><br />@ Eduardo<br /><br />Mir scheint, Sie reagieren teilweise etwas dünnhäutig. Warum? Ich freue mich, dass ich hier einer hochinteressanten, konstruktiven Diskussion beiwohnen konnte. Die Art und Weise, wie hier diskutiert wurde, hatte für mich etwas von "science at its best".<br /><br />Mit "dünnhäutig" meine ich z.B., dass Sie "cherry picking" ansprachen, so, als müssten Sie sich gegen diesen Vorwurf verteidigen (den niemand erhoben hat). Für mich beinhaltet "cherry picking" die Absicht, mit Tricks zu täuschen, daher habe ich nie diesen Begriff hier benutzt. Es ging doch nie um ihre Person oder gar ihre Integrität, sondern einzig um die Frage, ob man die Argumentation im Sinne eines Hypothesentests benutzen kann. <br /><br />Danke,<br />AndreasAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-63583662497498956062014-01-31T20:21:12.640+01:002014-01-31T20:21:12.640+01:00Indeed, see the trend slopes of climate models: ht...Indeed, see the trend slopes of climate models: http://climateaudit.files.wordpress.com/2013/12/fig-1-tcr-post-cmip5-79-13-temp-trends_ca24sep13.png?w=720&h=480 .<br />( the figure was made by Nic Lewis). No one must wonder that the data match very well a "below model trend" and so the message684953 28 of taminos post is: The trend slopes of the models are too high. If it was his intention? ;-)Franknoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-80253193275836496802014-01-31T19:40:13.299+01:002014-01-31T19:40:13.299+01:00The trend 0.12 C/decade agrees perfectly with the ...The trend 0.12 C/decade agrees perfectly with the average warming since 1950 that AR5 indicates as equal to the most likely rate of anthropogenic influence. It does not agree as well with most climate models.<br />Pekka Pirilähttp://pirila.fi/energynoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-12296668219506789042014-01-31T19:10:05.925+01:002014-01-31T19:10:05.925+01:00Rainer, are you sure? From taminos comment: "...Rainer, are you sure? From taminos comment: "That kind of cherry-picking requires a large compensation to statistical analysis, one which makes it clear that there’s no justification for a massive research project to investigate the post-1998 blazing heat. It also makes clear that there’s no justification for running off at the mouth about the so-called “pause.”<br />Is he right? He made a "strait foreward" analyse and took the trend 1975...1997 and stretched it, anyway...in his post one never reads something about the slope: it's 0,12K/ decade (GISS). Quite low, isn't it? Take another approach: Stretch the trend from 1987 to 2005 ( also a 19 years long interval...) to both ends- to 1979 on the one and to 2013 on the other. The slope is 0.2 K/decade...and voila: The temperature data from 2011 on are well below sigma of the trend 1987...2005. What have I done? I cherry picked an interval for the trend calculation, it has the same length as this of tamino. The slope of the trend is in the region of the IPCC- forecasts (0.2 deg/decade) and the same did tamino, never mentioned his quite low trend slope. What could be a proper approach: a 9 year lowpass...and the pause is clearlxy visible. See http://www.dh7fb.de/nao/taminocherry.gif .Franknoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-69290500868258337372014-01-31T14:05:08.572+01:002014-01-31T14:05:08.572+01:00Reiner #22
Thanks for the link to Tamino's ar...Reiner #22<br /><br />Thanks for the link to Tamino's article. Note that he is addressing a quite different question than Zorita/von Storch. He asks whether the post-1998 record is consistent with the hypothesis that global warming continues unabated in the way it was observed between the seventies and 1998. In other words he is taking a cheap shot at the "sceptics" who claim that there would be evidence that global warming has stopped.<br /><br />His analysis is straight forward and clear-cut and the answer is "yes". While he was also inspired by the public attention to the "hiatus", his question is not scientifically interesting - anybody who has looked at temperature plots long enough comes to the same conclusion by unaided eye inspection. He is doing public education. This is in contrast to Zorita/von Storch, who address an important and topical question.hvwnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-45452594753070539502014-01-31T13:28:28.080+01:002014-01-31T13:28:28.080+01:00Eduardo
I am not sure whether I understood your p...Eduardo<br /><br /><i>I am not sure whether I understood your paragraph properly. Do you mean to select an extreme observation from a sample and use that very same sample to construct the distribution of the HO ?</i><br /><br />No, that is not what I meant. I argue that even without the "Mexican hat"-fallacy the method is not terribly meaningful.<br /><br />1. You look at an observed time-series and select an extreme trend.<br /><br />2. <b>Then</b> you calculate the fraction of trends that are more extreme than the one from step 1 <b>from a freshly obtained set of time-series</b>. Assume that the freshly obtained set of time series is from the same population than the observed one, e.g. being the result of an ensemble model simulation with "the perfect climate model".<br /><br />3. Find that this fraction is below 0.05 quite often and that consequently it is quite likely for you to conclude that that "perfect model" is imperfect.<br /><br />You can check this easily by simulating a synthetic climate, say as<br />an AR(1) process, phi=0.2, sigma=0.1 K, with trend 0.02 K/y.<br />That is a poor replacement for real climate, but if my claim holds, then the onus is on you to show that it doesn't hold for real climate.<br /><br /><i>In comment 2 I was trying to explain to Andreas the basic reasoning, as he seemed to be confused.</i><br />His confusion seemed to stem from the very issues we were discussing in the following, not from failure to get the basic idea of a statistical test.<br /><br /><i>The calculation is not formally a test for more fundamental reasons than cherry pecking, namely we do not know what the model ensemble represents in a 'model space'</i><br /><br />I can live with what you consider "a more fundamental problem", precisely because it is unavoidable if you deal with questions like that. Also soft knowledge and general expertise can serve to bracket the error introduced and results might still remain indicative of something.<br /><br />The other problem, which I focus on, only shows up if you limit yourself to a particular 15-year trend to obtain information about whether and how climate models are wrong.<br /><br />I believe too that "something important is missing in the models". Particularly with respect to the representation of decadal variability. I am afraid that your calculation doesn't contribute to that belief (but only after thinking about it a bit more, inspired by your comment :).<br /><br />Your comment #18. "How long has the low trend to continue until we have some evidence that the models are wrong in a related way?"<br /><br />I'd argue that if your analysis says "20 years" then we have to wait 20 years from now on to conduct the test.<br /><br /><br /><br /><br /><br />hvwnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-42356828414330420032014-01-31T11:51:28.534+01:002014-01-31T11:51:28.534+01:00@ 35
I am not sure whether I understood your para...@ 35<br /><br />I am not sure whether I understood your paragraph properly. Do you mean to select an extreme observation from a sample and use that very same sample to construct the distribution of the HO ? If this is what you mean, of course this is the Mexican-hat paradox. It is , however, not the calculation presented here. <br />The distribution is constructed from the CMIP5 models. These data have been recently made available and are independent of the observe dtrend (no tuning...).<br />In the Mexican paraddox one can tell the results of test *exactly* prior to conducting the test itself. in other words, it is an artefact. Here, no one could know the results before hand. One could guess, for instance from the CMIP3 models, but that would be a physically based guess, not a physical artifact. If. for instance, the internal variability of the CMIP5 models were larger than in the CMIP3 models, the results of the test would have been different. Or if calculating overlapping or non-overlapping trends. <br />I agree that the cherry-picking caveat may apply, but not the Mexican-hat paradox, as I understand it.<br />Imagine that we are in 2100 and the trend has been zero. You could formally argue that the Mexican-hat paradox apply as well, and the calculation is not valid. This would be paradox in itself. The calculation cannot be formally valid depending in the length of the period: invalid if 15 years, valid if 100 years. <br /><br /><br />'The HO proposed by Georg is different from what you have written...'<br />Do you mean my comment 24 ?<br />yes, it is different. That comment is not supposed to be an answer to Georg and it is not tagged as such. It is just general information. <br /><br /> And your post #2, to which I was referring, clearly shows that this is how you think about it.'<br />'<br />In comment 2 I was trying to explain to Andreas the basic reasoning, as he seemed to be confused. The calculation is not formally a test for more fundamental reasons than cherry pecking, namely we do not know what the model ensemble represents in a 'model space'<br /><br />But indeed I think that the calculation is strongly indicative that something important is missing in the models, as I explained: either another forcing, or internal variability or sensitivity. From my informal contacts in the last months, I am not alone here.eduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-25358828145100965232014-01-31T11:10:07.524+01:002014-01-31T11:10:07.524+01:00Eduardo,
thanks for the extensive answer (#17).
&...Eduardo,<br /><br />thanks for the extensive answer (#17).<br />"Mexican Hat-ness" is not properly defined and it is a mess, that in these types of statistics, the a priory knowledge and even the intention of the researcher plays a role, which is not considered in the formalism. In this case I seem not to be alone with my perception.<br /><br />A stronger statement: You have a number of n time-series from the same, "real" climate (X_(1..n)), draw one (X_1, "observations"), select and extreme 15-y trend (T_ext) from X_1 (that can be max(trend), min(trend), min(abs(trend)), whatever), and calculate the fraction (f) of the trends in all X_(2..n), "perfect model simulations" that are more extreme than T_ext. That would be about your method here in the "H0 is true"-case.<br /><br />If f is smaller than, say 0.05, you somehow take that as an indication, painstakingly avoiding terminology from statistical testing though, that the ensemble of models (in this case an initialization ensemble of the perfect model) does not represent real climate. But in fact it does.<br /><br />It is straightforward to show that you'd come to the wrong conclusion here much more often than acceptable if you want your method to be meaningful.<br /><br /><i>The HO proposed by Georg is different from what you have written...</i><br />The rest of the conversation makes perfect sense with my understanding of what Georg proposed. Must be some mis-understanding.<br /><br />[But I think stating the result as "... hypothesis rejected at the x% level" is misleading.]<br /><i>And we didnt, if i recall properly. In our manuscript.</i><br />You kind of didn't, right. But you kind of suggest, by leaving out how else this result should be interpreted, that it is still to be understood as some sort of, maybe not totally correct, but still strongly indicative, test. And your post #2, to which I was referring, clearly shows that this is how you think about it.<br /><br />[Variance of linearly de-trended period]<br /><i>There is no direct way to estimate this from observations, without knowing what the forced variability is.</i><br />I guess I agree.<br />hvwnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-34269539607553099042014-01-31T08:03:19.960+01:002014-01-31T08:03:19.960+01:00Yes, Eduardo, they spent most of their efforts on ...Yes, Eduardo, they spent most of their efforts on the Arctic due to the issues with land-ocean-ice. But they also did an infill for Africa, and you definitely suggested they did not.<br /><br />Also, the argument for using UAH rather than RSS is that the latter excludes the high latitudes (that is, no coverage at all). The people at RSS have a good reason to ignore that data, and the problem is likely also present in the UAH data, but that is why they spend so much time on that hybrid approach. Note that Cowtan and Way thus do _not_ argue that they use UAH because RSS has poor properties at high latitudes.<br /><br />Your last figure just shows what Cowtan and Way show: leaving out the arctic (and large parts of antarctic) has a major downward effect on the trend. RSS actually has a larger trend in the tropics than UAH, so your suggestion is highly unlikely.<br /><br />A final note: my "secondary source" is the first author of the paper showing what they have done.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-597121947844380502014-01-30T23:05:59.599+01:002014-01-30T23:05:59.599+01:00@ Bam,
you may also benefit from reading the orig...@ Bam,<br /><br />you may also benefit from reading the original article, instead of secondary sources.<br /><br />'The Arctic is likewise the primary source of<br />uncertainty in this work. Further work is needed to address the differing behaviour of the land and ocean domains.'<br /><br />Actually, two methods of interpolation have been applied. Only the results of the hybrid method are included in the paper, the method that 'should work better over ice'.<br />If I did not overlook it, no trend correction is given by the simple kriging method, unless it is in the supplementary material, which I have not read. <br /><br />So, this paper targeted the Arctic specifically, and also used, in the hybrid method, the satellite data from UAH, not from RSS. Looking at my last figure in the post, one may wonder why.. The authors argue that the RSS data have poor properties at high latitudes. But one may also wonder that if they had used the RSS data over the tropics, their correction to the HadCRUt trend could have been even negative.eduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-18150035018860296842014-01-30T22:41:59.013+01:002014-01-30T22:41:59.013+01:00I start by noting that what I had in mind when I w...I start by noting that what I had in mind when I wrote my above comments is close to what von Storch wrote in #21 and #23.<br /><br />@Georg #25<br />Yes, fixing the starting point may involve cherry picking, but that's noise in the basic near impossibility of avoiding more severe cherry picking when the data is already known. <br /><br />Furthermore there are perfectly valid tests for determining whether a period defined by some conditions is exceptionally long with predefined statistical confidence, assuming that other conditions of testability are satisfied (they are not in this case).<br /><br />This is a very common dilemma in all fields where most data is historical and new data accrues too slowly. The fundamental dilemma is that tests are unavoidably formulated (to mention just two issues)<br /><br />- Knowing that nothing more dramatic has occurred than actually has. This is in many cases a very essential source of bias, because exceptionally strong phenomena may have a large influence in spite of their rareness.<br /><br />- Tests are typically developed to get a maximally clear indicator for the small likelihood of what appears exceptional in the data. Because the number of different possible "black swans" is very large, one of the many is much more likely to occur than any specific one. When the likelihood of only that one that has really occurred is considered, severely wrong conclusions may be drawn.<br /><br />There are many other reasons that make it very difficult or virtually impossible to judge, when an observation is really significant, and when not.<br /><br />At some point a longer and longer hiatus starts to be really significant, but what's that point?Pekka Pirilähttp://pirila.fi/energynoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-14448995231337554202014-01-30T20:46:24.247+01:002014-01-30T20:46:24.247+01:00@Pekka, others: granting that strict hypothesis te...@Pekka, others: granting that strict hypothesis testing may not be appropriate, one would think that common sense would be. These models were finalized around the start period of this time period. Since that time, they have one and all drifted hot, pretty much together, pretty much all runs, pretty much consistently. There are essentially no models left that are doing a good job.<br /><br />It would be nice if you all could make this statistically precise, but I would think that any rational person ought to conclude that we need new models, and that these models should not be used for overall surface temperature prediction.<br />If someone would verify that the out-of-sample error is much bigger than the in-sample error (before the models were fixed), a rational person should conclude as well that the models were tuned/curve-fitted whether the modelers think so or not. I don't know what the fix for that would have to be.MikeRhttps://www.blogger.com/profile/00127456522803816485noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-57326335600668623512014-01-30T20:15:12.809+01:002014-01-30T20:15:12.809+01:00@Georg Hoffman
Perhaps Curry changed her mind. Cow...@Georg Hoffman<br />Perhaps Curry changed her mind. Cowtan and Way did an outstanding job of engaging with skeptics both at Curry's blog and at climateaudit. I came away with the impression that their work was pretty good, and I think others there were impressed as well. Not saying the work is right, but they did well in defending it.MikeRhttps://www.blogger.com/profile/00127456522803816485noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-11727126084839542362014-01-30T19:23:08.624+01:002014-01-30T19:23:08.624+01:00Eduardo, you may benefit from reading this:
https:...Eduardo, you may benefit from reading this:<br />https://skepticalscience.com/global-warming-since-1997-more-than-twice-as-fast.html<br />The Figure answers your question about Africa.<br /><br />For those who wonder: Cowtan and Way actually did what Eduardo wonders about them not doing: they looked at coverage bias in Africa, too. In fact, they did so for the whole globe, applying their method to get essentially full coverage. <br /><br />Bam<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-86919041415284076742014-01-30T17:12:46.540+01:002014-01-30T17:12:46.540+01:00An argument could be also made here that the focus...An argument could be also made here that the focus on the Arctic is also a kind of cherry-picking, since we a priori know that Arctic temperatures have risen faster. Why not focus on Africa and try to fill the data gaps there ?<br /><br />Independently of the Arctic, however, there is still a 'remarkable' difference between models and observations (let us formulate it in that way). Fyfe, Gillet and Zwiers did mask the model data according to the availability of the HadCRUT4 observations and they still find that the observed HadCRUT4 trend is at the fringe of the model ensemble.<br /><br />I think that a more constructive stance is to ask ourselves what are the model missing, and why their internal variability seem to be smalleduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-42975889882566674622014-01-30T17:01:56.737+01:002014-01-30T17:01:56.737+01:00@Edu
From the very friendly and positive Nature op...@Edu<br />From the very friendly and positive Nature opnion peace of Judith<br /><br />"Laudably, Cowtan and Way have made their data and computer code available following publication of their paper "<br /><br />and <br />"Cowtan and Way4 present an alternative way of handling regional gaps in the surface temperature record, and conclude that the slower warming over the past 15 years or so has not been as significant as thought."<br /><br />on one side<br /><br /><br /><br />and from the rather harsh an negative evaluation of the paper from the website of Mrs Curry<br /><br />"So I don’t think Cowtan and Wray’s analysis adds anything to our understanding of the global surface temperature field and the ‘pause.’"<br /><br /><br />So it does not add anything at all to our knowledge but I write an article about it how much I like it.<br />Funny.Georg Hoffmannhttp://scienceblogs.de/primaklima/noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-11432244723869378452014-01-30T16:35:20.194+01:002014-01-30T16:35:20.194+01:00More on this in Nature by J. CurryMore on this in <a href="http://www.nature.com/ngeo/journal/v7/n2/full/ngeo2078.html" rel="nofollow">Nature by J. Curry</a>eduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-92089830153615206982014-01-30T11:31:13.818+01:002014-01-30T11:31:13.818+01:00@Edu
"ich denke nicht. koennte es nicht so se...@Edu<br />"ich denke nicht. koennte es nicht so sein, dass in beiden Faellen die interne Modellvariabilitaet zu klein ist (war) und die geforceten Trends in der Mitte zwischen 88-98 und 98-2012 liegen ?"<br /><br />Das meinte ich. Wenn einmal zu hoch und einmal zu niedrig, dann koennte es eine Problem mit der Variabilitaet sein.<br /><br />@Pekka<br />I dont understand your answer. Even if for a reason I dont yet understand the end of the observed data serie is a "natural" point the fact of loocking 10,15 or 20 years back is picked- cherry or not.<br />Georg Hoffmannhttp://scienceblogs.de/primaklima/noreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-1320418801778258672014-01-30T11:17:21.002+01:002014-01-30T11:17:21.002+01:00The trend in HadCRUT4 for the period 1984-1998 was...The trend in HadCRUT4 for the period 1984-1998 was 0.26 K/decade, which corresponds to the 64% percentile of the simulated trend ensemble as calculated here (2005-2006, scenario RCP4.5) Thus, the observed trend was a bit higher than the median value, which is 0.23 K/decade.<br />The 95% percentile is 0.41 K/decade; the 5% percentile, 0.08 K/decadeeduardohttps://www.blogger.com/profile/17725131974182980651noreply@blogger.com