tag:blogger.com,1999:blog-9093436161326155359.post6486294706358478105..comments2024-03-28T06:43:02.954+00:00Comments on Variable Variability: On the reactions to the doubling of the recent temperature trend by Curry, Watts and LuciaVictor Venemahttp://www.blogger.com/profile/02842816166712285801noreply@blogger.comBlogger22125tag:blogger.com,1999:blog-9093436161326155359.post-1998115327655725122013-11-21T15:44:43.101+00:002013-11-21T15:44:43.101+00:00Well, baseline choice doesn't change that the ...Well, baseline choice doesn't change that the rate of warming over the past 20-25 years is clearly at the low end of the CMIP5 envelope. The longer view does provide some perspective though - it wouldn't at all be the first time that observed 20-25 year trends have transgressed outside the model range, and yet century-scale warming is comfortably within the envelope.Paul Shttps://www.blogger.com/profile/15275182941476518621noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-9109783084459080892013-11-20T16:39:41.638+00:002013-11-20T16:39:41.638+00:00Paul, thank you. Amazing how important the baselin...Paul, thank you. Amazing how important the baseline is if you are looking at details such as the warming over the last decade.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-73176806139923587592013-11-20T14:37:21.389+00:002013-11-20T14:37:21.389+00:00Regarding Ed Hawkins' plots, it's worth ke...Regarding Ed Hawkins' plots, it's worth keeping in mind that the model spread and position of observational time series within the spread are highly baseline-dependent.<br /><br />A 1961-1990 or 1986-2005 baseline makes some sense if you're only interested in the most recent couple of decades but if you want some longer-term perspective on model-observation comparison using these can throw up some odd features, as shown on <a href="http://tenfourrecords.com/images/cmip5tasonly-19611990.png" rel="nofollow">this plot</a>.<br /><br />[Brief description: I've clipped to 60ºS-60ºN (both model and obs data) as a rudimentary masking procedure to avoid comparison to very high-latitude regions with poor observational sampling. NOAA is used instead of HadCRUT4 because of better sampling within 60ºS-60ºN. I only had the historical runs available so model data stops at 2005; hopefully it's not too difficult to track the trajectory by eye up to 2012. Where multiple realisations were supplied for individual models the ensemble mean was used. My intuition is that this kind of plot wouldn't be far different if all realisations were included separately, but the model spread might be slightly reduced by this procedure.]<br /><br />Note how the spread is fairly tight in the latter period but widens considerably earlier in the record. In terms of the experimental concept this doesn't make sense because the idea is surely to see how different models evolve over the historical period, rather than forcing them to converge at the end.<br /><br />Using more natural baselines for longer-term change, say <a href="http://tenfourrecords.com/images/cmip5tasonly-18801930.png" rel="nofollow">1880-1930</a> or <a href="http://tenfourrecords.com/images/cmip5tasonly-19011950.png" rel="nofollow">1901-1950</a> (as seen in AR4), reveals a different story where models generally warmed less than observations until the early-2000s. At the end of the record obs are running just below the median but comfortably within the 5% lower bound.<br /><br />Beyond the coverage issue another small source of bias not usually accounted is the use of global SAT from the models to compare with land SAT+ocean SST observations. I tried producing a <a href="http://tenfourrecords.com/images/cmip5tassst-18801930.png" rel="nofollow">SAT+SST composite</a> by obtaining separate "global" averages for SAT and SST then combining by weighting according to relative surface areas of land and ocean.Paul Shttps://www.blogger.com/profile/15275182941476518621noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-52904629998238068542013-11-19T21:31:51.065+00:002013-11-19T21:31:51.065+00:00Glad you like it. :-) I am blogging in my free tim...Glad you like it. :-) I am blogging in my free time. You also have to have some fun.<br /><br />Judith Curry is just sending her people over here. I will get in trouble for this list. :-)Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-22978514231607375392013-11-19T21:20:21.848+00:002013-11-19T21:20:21.848+00:00[Re: Victor Venema Monday, 18 November 2013 21:50:...[Re: Victor Venema Monday, 18 November 2013 21:50:00 GMT]<br /><br />Ha ha! :) No, no. My not being a native English-speaker either, by "touches of irony" I just meant funny bits like:<br /><br />"As a goal-oriented guy, Anthony Watts found the two most erroneous statements" XD<br /><br />"Talking about the ostriches the way one talks when they are not in the room, makes the climate ostriches go mad in the comments. I would advice any ostrich with blood pressure problems not to watch this video. The video is called "How to talk to a climate change denier" and halfway Marshall explains that that term is best avoided in a productive conversation." XD<br /><br />"I really wonder why John Cristy of the UAH dataset should chime in. He is the one that delivers a dataset with values in the Arctic. Maybe it would be better to ask the mainstream scientists behind the RSS dataset. They are the ones that did not trust the data sufficiently and rather leave a gap in the Arctic." XD<br /><br />:)Jesús R.https://www.blogger.com/profile/08623637876422608968noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-51590131266800597012013-11-19T20:41:21.685+00:002013-11-19T20:41:21.685+00:00Anonymous, could you be more specific and explain ...Anonymous, could you be more specific and explain why you think one of my statement is wrong? Then maybe would could have a civilized discussion here.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-6822549276367814622013-11-19T20:32:31.274+00:002013-11-19T20:32:31.274+00:00why do you lie?why do you lie?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-18717342086048814342013-11-19T18:11:54.043+00:002013-11-19T18:11:54.043+00:00Hi Victor,
Nice summary and thanks for the mentio...Hi Victor,<br /><br />Nice summary and thanks for the mentions.<br /><br />I have also added a new comparison of the Cowtan & Way results to my blog today:<br /><br />http://www.climate-lab-book.ac.uk/2013/updates-to-comparison-of-cmip5-models-observations/<br /><br />cheers,<br />Ed Hawkins<br />Ed Hawkinshttp://www.climate-lab-book.ac.uknoreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-12842960502684685022013-11-19T14:00:22.337+00:002013-11-19T14:00:22.337+00:00Rodger, thank you very much for the links to the u...Rodger, thank you very much for the links to the updates. I will put them in the article.<br /><br />I do have to say, that climate only changes slowly. Thus a 10 year old plot is still recent as long as the methods are up to date. We should relax a little and in an anti-zen approach not focus so much on the present.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-8856795008419366152013-11-19T11:46:28.517+00:002013-11-19T11:46:28.517+00:00The Ed Hawkins graphic featured in the post is a l...The Ed Hawkins graphic featured in the post is a little out of date. A more up-to-date version of the same graphic using HadCRUT4 dates to <a href="http://www.climate-lab-book.ac.uk/2013/updated-comparison-of-simulations-and-observations/" rel="nofollow">this February</a> although a clearer version appeared <a href="http://www.climate-lab-book.ac.uk/2013/comparing-observations-and-simulations-again/" rel="nofollow">in May</a>.<br />(Fingers crossed the HTMLs work.)MA Rodgerhttps://sites.google.com/site/marclimategraphs/noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-64407258135651165272013-11-18T21:50:32.703+00:002013-11-18T21:50:32.703+00:00You mean the unintended touches of irony by a stru...You mean the unintended touches of irony by a struggling non-native speaker? It is hard to detect irony on the net.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-87910244854458076332013-11-18T21:35:32.790+00:002013-11-18T21:35:32.790+00:00Just discovered this blog. It's great, thank y...Just discovered this blog. It's great, thank you for the detailed explanations and the entertaining touches of irony. I'll keep tuned.Jesús R.https://www.blogger.com/profile/08623637876422608968noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-7482920393332755372013-11-18T20:39:16.054+00:002013-11-18T20:39:16.054+00:00Fixed the saves. A classic. Thanks.
Doesn't &...Fixed the saves. A classic. Thanks.<br /><br />Doesn't "critical" have a second meaning in English? More in the direction of "negative", which I found to be a bit too negative.<br /><br />When I first read her comments, I found them not too bad, except for missing that the methods were carefully cross-validated. And I seem to have somehow missed the sneer at the time.<br /><br />One of the advantages of writing is that it helps to gather your thoughts. I must admit that after writing this post, I am left with the feeling that she mainly did not like the conclusion. I do not see much substance.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-72880180361514099892013-11-18T19:58:19.601+00:002013-11-18T19:58:19.601+00:00> The main serious critical voice seems to be J...> The main serious critical voice seems to be Judith Curry at Climate Etc<br /><br />I think you're being overly generous here, if by "critical" you mean "careful reasoned analysis". I get the strong impression that she hadn't really read the paper. I think she skimmed it well enough to put up a few quibbles, and you've discussed those. But as the comments by C+W show, her comments are shallow and in many cases are answered by the paper itself.<br /><br />Even those quibbles are too waek to justify her "doesn't add anything" sneer; that's really rather pathetic of her. She isn't brave enough to reject it, she's not inclined to accept it, so she's trying on an elder-statesman like distain. Which is what her followers want, and its good enough to get her quoted. But as a logical argument, its nothing but hole.<br /><br />[Minor English correction: you say "save" several times when you mean "safe".]William M. Connolleyhttps://www.blogger.com/profile/05836299130680534926noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-9847579840884721472013-11-18T17:25:35.434+00:002013-11-18T17:25:35.434+00:00I meant to say I'm probably NOT qualified to s...I meant to say I'm probably NOT qualified to say this. Forgot the NOT.Rachelhttps://www.blogger.com/profile/09129841408329015509noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-84600571707458146222013-11-18T17:24:47.755+00:002013-11-18T17:24:47.755+00:00This is great, Victor. Thanks for posting it.
I ...This is great, Victor. Thanks for posting it. <br /><br />I definitely agree with Andrew's comment about Judith Curry suggesting this paper adds nothing to our understanding. That's a crazy statement. A more likely contender for most useless paper is her own stadium wave one, although I'm probably really qualified to say this.Rachelhttps://www.blogger.com/profile/09129841408329015509noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-86840966267403429022013-11-18T14:46:56.042+00:002013-11-18T14:46:56.042+00:00Hi Marco, nice to see this independent result from...Hi Marco, nice to see this independent result from <a href="http://moyhu.blogspot.dk/2013/11/coverage-hadcrut-4-and-trends.html" rel="nofollow">Nick Stokes</a>. Thanks.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-83863926521096912602013-11-18T14:32:42.280+00:002013-11-18T14:32:42.280+00:00Victor, also note Nick Stokes' analysis. He...Victor, also note Nick Stokes' analysis. He's used a much more simplified method to look at the coverage issue, which finds a similar result as that of Cowtan and Way:<br />http://moyhu.blogspot.dk/2013/11/coverage-hadcrut-4-and-trends.html<br />No need for any kriging or comparison with satellites in his method!<br /><br />MarcoAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-19296576621047034482013-11-18T12:09:56.938+00:002013-11-18T12:09:56.938+00:00R. Daneel, I would say that Motl makes WUWT look l...R. Daneel, I would say that Motl makes WUWT look like a quality blog. Watts argument may have been wrong, but at least it was an argument.<br /><br />Andrew, I fully agree. Noting the sensitivity to the start date is another way of noting how large the uncertainty is for such a climatologically short period. It is fine to compute such a thing. The climate systems shows variability at all temporal and spatial scales and you can thus study trend on all spatial and temporal scales. It would be wrong however, to interpret such trends over short periods as a stop in the warming of the atmospheric surface temperature. Even the word slowdown of the surface temperature is already not really warranted as there is no statistically significant change in the trend.<br /><br />Lars, yes. Or maybe he does not believe it. :-) But, I guess this could simply be an honest mistake due to lack of experience with satellite data.Victor Venemahttps://www.blogger.com/profile/02842816166712285801noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-75609243226654282342013-11-18T12:00:55.080+00:002013-11-18T12:00:55.080+00:00Watts: "Note how the data near the poles star...Watts: "Note how the data near the poles starts to get spotty with coverage?"<br /><br />So basically Watts forgot that Earth is round!Lars Karlssonhttps://www.blogger.com/profile/06158469980966810882noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-35702103436045311022013-11-18T08:18:18.326+00:002013-11-18T08:18:18.326+00:00Victor,
Interesting analysis, thank you.
A coupl...Victor,<br /><br />Interesting analysis, thank you.<br /><br />A couple of point occur to me regarding Curry's criticisms. Firstly, it seems to me that whether or not one sees a 'pause' in the UAH record seems to be very dependent on the start date which is chosen. This is also true to an extent with HadCRUT but seems to be more so with the satellite records, maybe because they show a more pronounced reaction to ENSO events. <br /><br />Secondly, although one could maybe argue that some of C&W's supporters have made stronger claims than are perhaps supported by their paper at this early stage, Curry's claim that it adds nothing at all to our understanding of temperature trends is astonishing - it just smacks of complete denial. I guess she has invested so much in promoting the significance of the 'pause' that she risks having a lot of egg on her face. <br /> <br /><br />andrew adamshttps://www.blogger.com/profile/17196332706764660436noreply@blogger.comtag:blogger.com,1999:blog-9093436161326155359.post-52018709269207648962013-11-18T01:14:59.321+00:002013-11-18T01:14:59.321+00:00Hehe. I would've love to read your reactions t...Hehe. I would've love to read your reactions to Lubos Motl's rant. Anonymoushttps://www.blogger.com/profile/07982409667756307764noreply@blogger.com