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  • IPCC « Climate Audit
    PM On August 3 I discussed the progress of David Holland s efforts to overcome obstruction by the University of East Anglia and the IPCC to a request under UK Freedom of Information legislation for a secret letter from Thomas Stocker to among others lead authors of IPCC AR4 I observed that many of the recipients of By Steve McIntyre Also posted in FOIA Uncategorized Tagged stocker Comments 48 More on the Iconography of IPCC 1990 Figure 7 Sep 30 2012 2 32 PM As a mild break from Lewandowsky s fake data and false results I am going to revisit IPCC 1990 Figure 7 which I discussed in several Climate Audit posts from 2005 2008 a topic that was raised at Lewandowsky s blog by conspiracy theorist John Mashey who rather than confronting the problems of Lewandowsky s use of fake By Steve McIntyre Also posted in Uncategorized Tagged connolley ipcc 1990 lamb mashey Comments 164 IPCC Refuses to Correct Errors Sep 13 2012 8 39 PM Pielke Jr has an interesting post about more IPCC nonsense He made four proposed error corrections to IPCC all of which were refused Which is the worst refusal is a bit of a beauty contest On balance I think that my favorite is their reason for refusing to correct an inaccuracy in an IPCC press By Steve McIntyre Also posted in Uncategorized Tagged IPCC pielke Comments 24 Older posts Tip Jar The Tip Jar is working again via a temporary location Pages About Blog Rules and Road Map CA Assistant CA blog setup Contact Steve Mc Econometric References FAQ 2005 Gridded Data High Resolution Ocean Sediments Hockey Stick Studies Proxy Data Station Data Statistics and R Subscribe to CA Tip Jar Categories Categories Select Category AIT Archiving Nature Science climategate cg2 Data Disclosure and Diligence Peer Review FOIA General Holocene Optimum Hurricane Inquiries Muir Russell IPCC ar5 MBH98 Replication Source Code Spot the Hockey Stick Modeling Hansen Santer UK Met Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith Kloor Klimazweibel

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  • hegerl « Climate Audit
    Comments 40 Hegerl Proxies 1 Mann PC1 Oct 24 2006 11 27 PM The Hegerl et al 2006 climate reconstruction is finally online here I m going to go through the proxies individually before talking about method Obviously the first one to look for is Mann s North American PC1 Although they say that they ve moved on Mann s PC1 was used in Osborn and Briffa 2006 and was one By Steve McIntyre Posted in Briffa Hegerl 2006 Mann PC1 Comments 85 When is an Upper Confidence Limit a Lower Confidence Limit Apr 20 2006 8 22 PM An odd question you say It s not something that usually expect in a statistical study But hey this is the Hockey Team with statistics by Frame of climateprediction net By Steve McIntyre Posted in Crowley Multiproxy Studies Comments 46 Hegerl et al in this week s Nature Apr 20 2006 8 10 AM There s a new study by Hegerl et al in this week s Nature which among other things describes the performance of something called the CH blend a secret blend of 12 proxies a secret somewhere up there with the Caramilk secret As I mentioned previously I requested the identity of the sites in the blend as By Steve McIntyre Posted in Hegerl 2006 Multiproxy Studies Comments 55 Tip Jar The Tip Jar is working again via a temporary location Pages About Blog Rules and Road Map CA Assistant CA blog setup Contact Steve Mc Econometric References FAQ 2005 Gridded Data High Resolution Ocean Sediments Hockey Stick Studies Proxy Data Station Data Statistics and R Subscribe to CA Tip Jar Categories Categories Select Category AIT Archiving Nature Science climategate cg2 Data Disclosure and Diligence Peer Review FOIA General Holocene Optimum Hurricane Inquiries Muir Russell IPCC ar5 MBH98 Replication Source Code Spot the Hockey Stick Modeling Hansen Santer UK Met Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith Kloor Klimazweibel Lubos Motl Lucia s Blackboard Matt Briggs NASA GISS Nature Blogs RealClimate Roger Pielke Jr Roger

    Original URL path: http://climateaudit.org/tag/hegerl/ (2016-02-08)
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  • manning « Climate Audit
    Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith Kloor Klimazweibel Lubos Motl Lucia s Blackboard Matt Briggs NASA GISS Nature Blogs RealClimate Roger Pielke Jr Roger Pielke Sr Roman M Science of Doom Tamino Warwick Hughes Watts Up With That William Connolley WordPress com World Climate Report Favorite posts Bring the Proxies up to date Due Diligence FAQ 2005 McKitrick What is the Hockey Stick debate about Overview Responses to MBH Some thoughts on Disclosure Wegman and North Reports for Newbies Links Acronyms Latex Symbols MBH 98 Steve s Public Data Archive WDCP Wegman Reply to Stupak Wegman Report Weblogs and resources Ross McKitrick Surface Stations Archives Archives Select Month February 2016 January 2016 December 2015 September 2015 August 2015 July 2015 June 2015 April 2015 March 2015 February 2015 January 2015 December 2014 November 2014 October 2014 September 2014 August 2014 July 2014 June 2014 May 2014 April 2014 March 2014 February 2014 January 2014 December 2013 November 2013 October 2013 September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 November 2008 October 2008 September 2008 August 2008 July 2008 June 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 2006 May 2006

    Original URL path: http://climateaudit.org/tag/manning/ (2016-02-08)
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  • o’dowd « Climate Audit
    al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith Kloor Klimazweibel Lubos Motl Lucia s Blackboard Matt Briggs NASA GISS Nature Blogs RealClimate Roger Pielke Jr Roger Pielke Sr Roman M Science of Doom Tamino Warwick Hughes Watts Up With That William Connolley WordPress com World Climate Report Favorite posts Bring the Proxies up to date Due Diligence FAQ 2005 McKitrick What is the Hockey Stick debate about Overview Responses to MBH Some thoughts on Disclosure Wegman and North Reports for Newbies Links Acronyms Latex Symbols MBH 98 Steve s Public Data Archive WDCP Wegman Reply to Stupak Wegman Report Weblogs and resources Ross McKitrick Surface Stations Archives Archives Select Month February 2016 January 2016 December 2015 September 2015 August 2015 July 2015 June 2015 April 2015 March 2015 February 2015 January 2015 December 2014 November 2014 October 2014 September 2014 August 2014 July 2014 June 2014 May 2014 April 2014 March 2014 February 2014 January 2014 December 2013 November 2013 October 2013 September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 November 2008 October 2008 September 2008 August 2008 July 2008 June 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 2006 May 2006 April 2006 March 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004

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  • solomon « Climate Audit
    Bureaucrats May 21 2007 9 35 AM IPCC has a policy requiring them to make all expert and government review comments available under the following terms All written expert and government review comments will be made available to reviewers on request during the review process and will be retained in an open archive in a location determined by the IPCC Secretariat on By Steve McIntyre Posted in IPCC Also tagged manning tsu Comments 230 IPCC and Data Access Mar 28 2007 12 57 PM One of the most important IPCC representations is the supposedly tremendous quality control of its review process I ve mentioned in passing on a number of occasions that when I sought to obtain supporting data for then unpublished articles IPCC threatened to expel me as a reviewer I ve had a few requests to recount my experience By Steve McIntyre Posted in Archiving Hegerl 2006 IPCC Also tagged d arrigo hegerl manning o dowd wilson Comments 116 US Climate Change Science Program Workshop Nov 19 2005 10 29 AM The U S Climate Change Science Program Workshop was the first such workshop that I d been to Sometimes the anthropology is as interesting as anything else By Steve McIntyre Posted in General Comments 6 Tip Jar The Tip Jar is working again via a temporary location Pages About Blog Rules and Road Map CA Assistant CA blog setup Contact Steve Mc Econometric References FAQ 2005 Gridded Data High Resolution Ocean Sediments Hockey Stick Studies Proxy Data Station Data Statistics and R Subscribe to CA Tip Jar Categories Categories Select Category AIT Archiving Nature Science climategate cg2 Data Disclosure and Diligence Peer Review FOIA General Holocene Optimum Hurricane Inquiries Muir Russell IPCC ar5 MBH98 Replication Source Code Spot the Hockey Stick Modeling Hansen Santer UK Met Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith Kloor Klimazweibel Lubos Motl Lucia s Blackboard Matt Briggs NASA GISS Nature Blogs RealClimate Roger Pielke Jr Roger Pielke Sr Roman M Science of Doom Tamino Warwick Hughes Watts Up With

    Original URL path: http://climateaudit.org/tag/solomon/ (2016-02-08)
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  • Wilson on Yamal Substitution « Climate Audit
    and post up the mean ring width version later in the day or tomorrow E E M Posted Feb 22 2006 at 10 52 AM Permalink Of interest A new doctoral thesis completed Is Antarctic snow record an inaccurate archive of historical temperatures English summary http www nwo nl nwohome nsf pages NWOA 6LJDZU Eng Opendocument 14 February 2006According to Dutch researcher Michiel Helsen annual and seasonal temperature fluctuations are not accurately recorded in the composition of the snow of Antarctica His research into the isotopic composition of the Antarctic snow has exposed the complexity of climate reconstructions Polar ice caps contain valuable information about the earth s climate Helsen investigated the extent to which meteorological data are stored in the composition of snow in order to improve the interpretation of deep ice cores from the Antarctic ice cap He demonstrated that annual temperature variations in Antarctica could not be accurately reconstructed from ice core investigations The conditions during snowfall are not representative enough for the average weather over an entire year His research also revealed that although temperature differences over the entire continent of Antarctica have a major influence on the composition of the snow there are strong spatial variations in this Accordingly a simple conversion of the fluctuations in the snow composition to changes in the local temperature is unreliable per Posted Feb 22 2006 at 11 43 AM Permalink fascinating We have no knowledge if variance should be or is similar through historical time yet the criterion is applied whatever It also appears to be a hidden data manipulation so there is no way we can tell if this criterion is applied throughout particular analyses or merely used for particular data sets I can even imagine how you could use the same argument to justify the choice of the other series If you looked at the variance through the calibration time period i e 1800 2000 then you could claim that the Yamal variance changes more than the other series and hence you are not using the Yamal series That would be an objective criterion We also don t know how the variance correlates with temperature a minor detail cheers per jae Posted Feb 22 2006 at 12 13 PM Permalink IMHO it s time for the Team to drop tree rings and move on It sure looks to me that it cannot be generally demonstrated that tree ring data are correlated to temperature Most of the trees show very little correlation if any Some groups of trees show negative correlations A few groups show good positive correlations but this may be spurious because of CO2 fertilization effects etc Maybe they can move on to other proxies But considering comment 6 maybe there are no good proxies But we have models McCall Posted Feb 22 2006 at 12 16 PM Permalink re this discussion clear statistical reasons for Yamal vs Polar Urals or vice versa and in light of Dr Hoyt in 4 selecting proxies based upon their stability may be suppressing real information about the weather and climate Can and how would similar arguments be applied to the rejection of Keigwin 96 Sargasso a proxy with clear MWP and LIA in MBH and the IPCC TAR Chapter 2 vs the chosen Keigwin and Pickart 99 Newfoundland a proxy with cooler MWP and warmer LIA It seems to me that the choice of either of these two proxies also tends to define what ones position is on AGW Steve Sadlov Posted Feb 22 2006 at 12 22 PM Permalink RE 9 Sargasso An interesting thing to contemplate An huge gyre corresponding with an overlying stable semi permanent area of atmospheric high pressure Ever since the Atlantic settled after the closure of the Ithsmus of Panama I reckon this regime has been in place Given the strength of both the Bermuda High as well as the near stagnant nature of Sargasso itself I would reckon that if anywhere on earth would be expected to average out noise and small excursions Sargasso is par excellence There are qualitative measures of the goodness of proxies based on a combination of logic tectonic configuration ocean current patterns atmosphering current patterns and naturally the biological tell tale of all that Sargassum McCall Posted Feb 22 2006 at 12 32 PM Permalink Strike my last editorial generalization It seems to me Moberg 05 used Keigwin 96 and greater climate variability over the millenium was the result vs an AGW theory advocacy The question of Keigwin proxy choices remains Martin Ringo Posted Feb 22 2006 at 1 31 PM Permalink First thanks Steve and Rob for having a civil and public discussion debate over analysis that underlies shall we say various conclusions Please do whatever you can to produce more of of same It is indeed interesting Second what variance Are you talking about the variance of the series itself or the variance of the residuals of the series as a dependent variable in some regression or other procedure And third if the answer is the series could you explain why homoskedastic is better than heteroskedastic for an individual series Again my thanks Steve McIntyre Posted Feb 22 2006 at 1 39 PM Permalink 12 In this context the issue is the variance of the ring width growth index the site chronology I don t see any reason why the index should be homoskedastic and would not set that as a criterion Rob has alluded to a link between the index between heteroskedastic series and inadequate adjustment for age in the trees but I don t see that the linkage is proved here Maybe Rob can clarify Gerald Machnee Posted Feb 22 2006 at 2 19 PM Permalink but from the attached figure the Yamal series is clearly superior to the RCS version Why is it superior Does it show a desired result John A Posted Feb 22 2006 at 3 16 PM Permalink Re 11 Would you please specify exactly what the problem is with the Sargasso Sea proxies used Neil Fisher Posted Feb 22 2006 at 3 34 PM Permalink Re 8 can anyone explain why if tree ring data is such a good climate proxy that one must select certain trees sites With some samples showing a negative correlation what sort of assurance do we have that even those that do show a positive correlation over the calibration period have the same correlation to temperature over larger time scales IMO the whole tree rings as a climate proxy is totally bogus without such an explaination and even if one is forthcoming which I doubt why do not all trees show a positive correlation to temperature John S Posted Feb 22 2006 at 3 44 PM Permalink Can you clarify what is meant by variance once more The 101 yr running variance plots suggests to me that you are talking about the variance of the annual series over a 101 year window where this is the variance of the final processed series rather than some earlier raw data Because 101 is odd this suggests it is a centred window that is used Not that this makes any difference here i e Var t var series t 50 series t 50 If this is the case how are trends taken into account For example during a period when the series is trending the variance will mechanically increase without it necessarily indicating anything about underlying homo or heteroskedasticity Or are we talking about some sort of cross sectional variance across trees in any given year That would make more sense to me in judging the robustness of a processed series but I don t have access to the reference Rob provided is there anything available on the Internet jae Posted Feb 22 2006 at 3 47 PM Permalink re 16 See Steve s posts under the category 1980s Proxies Greg F Posted Feb 22 2006 at 4 03 PM Permalink Should the Instrumental Record be rejected on the same grounds McCall Posted Feb 22 2006 at 4 23 PM Permalink re 15 re 11 I see no problems with Keigwin 96 Sargasso neither did Moberg 05 MBH 98 99 and IPCC 01 TAR rejected it though and we all suspect a different reason than how they justified the omission rejection which Moberg 05 just plain ignored Refer to para 6 last of http www grida no climate ipcc tar wg1 070 htm Post 89 at http www realclimate org index php p 122 Post 13 at http www realclimate org wp comments popup php p 180 c 1 Start with Post 1 with a deafening no RC response http www realclimate org index php p 122 My apologies for taking this discussion off track I know this is Yamal and Urals thread I to am appreciative of the polite and open discussion between Wilson and McIntyre But having been recently audited a class by Professor Calorie J Thermos who among other insights argues putting thermometers in ice water isn t such a bad idea I m requesting a revisit with new clear statistical reasons related to variance changes through time eyes to this thread http www climateaudit org p 145 Taken By Storm Willis Eschenbach Posted Feb 22 2006 at 5 11 PM Permalink Re 19 Greg F looks like the instrumental record is toast bad variation no cookies Again my unrelated plea HELP I can t find on this cite the study and graph that M M did using the corrected methods and data of MBH98 the one that showed a higher 14th century temperature Grrrr w McCall Posted Feb 22 2006 at 5 14 PM Permalink Correction to 20 last para I too Having recently audited Hans Erren Posted Feb 22 2006 at 5 34 PM Permalink re 21 fig 8 page 766 McIntyre S and McKitrick R 2003 Corrections to the Mann et al 1998 proxy database and northern hemisphere average temperature series Energy and Environment 14 6 751 771 http www friendsofscience org documents m m pdf Martin Ringo Posted Feb 22 2006 at 5 45 PM Permalink Re 19 and 21 temperature variation The instrument record may or may not become toast I guess that depends on how much it warms up But the higher variance in the earlier years is almost certainly a reflection of the number of stations that go into the regional or global average That is what one is seeing is the greater local deviations effect in the early years because there are fewer stations to average those deviations over Our host discussed a similar issue post with regard to the various proxy reconstructions with differing numbers of proxies Martin Ringo Posted Feb 22 2006 at 5 48 PM Permalink Re 16 8 While I cannot speak for the dendrochronology crowd there is an argument albeit not a particularly wonderful one for selecting certain variables I should also note that everyone should be rightfully skeptical of procedures that select one variable over another Anyway the argument proceeds as follows suppose that tree ring width were truly explained by the following equation RW B0 B1 X B2 Z error where X is temperature and Z is some other explanatory variable s usually not measured Then in data sets where there is lots of variation in Z the omitted and unobserved variable s the correlation between Y and X will often be confounded In order to better measure the B1 the effect of X one might look at those sets of Y s and X s in which the correlation is clearly evident as a proxy for cases where the variation of the Z s is relatively unimportant A problem with this approach is that if Y is regressed on X without Z there is an omitted variable bias if there is correlation between X and Z Of course the researcher isn t going to know which way the bias is without having a measurement of Z But if one selects just those cases in which the correlation of Y and X is positive it is almost certainly biasing the estimate of B1 upward In the tree ring case it would seem to be better to estimate the B1 coefficient from forestry studies in which there are good measurements on the Z s i e the omitted variables then use the coefficient estimate in the reconstruction If those species with the long chronologies however do not have the forestry type analyses I think that one has to live with the grand average effect mixing the positive negative and nil correlations regardless of the result in order to keep the estimate unbiased But then I am not a dendrochronologist and hence I m only speculating on the reasoning and problems behind the selection of data sets Steve McIntyre Posted Feb 22 2006 at 5 50 PM Permalink I don t have time pre NAS to think about this issue in terms of a Demetris Koutsoyannis viewpoint but I think there s a connection I ll post David Stockwell on this but if you have long term persistence it s certainly not obvious that the kind of variance stabilization that Rob is selecting on is something that you should necessarily be seeking I m not saying the opposite only that it s not obvious at least to me and needs to be thought through Steve McIntyre Posted Feb 22 2006 at 5 51 PM Permalink 25 Martin surely this leads precisely into the data mining trap discussed in Ferson et al 2003 where the confidence intervals explode jae Posted Feb 22 2006 at 6 11 PM Permalink Re 25 If those species with the long chronologies however do not have the forestry type analyses I think that one has to live with the grand average effect mixing the positive negative and nil correlations regardless of the result in order to keep the estimate unbiased Exactly But if you do this the large variability due to z simply overshadows x so you have to tweak things cherry pick or play some statistical game to get a relationship between y and x jae Posted Feb 22 2006 at 6 18 PM Permalink And then you throw in the non linearity too Martin Ringo Posted Feb 22 2006 at 7 37 PM Permalink Re 28 jae first I should have said relatively unbiased not unbiased The problem isn t so much that Z s effect say habitat competition overwhelms the X say temperature but that temperature and habitat competition may be correlated and without including it or an instrumental variable IV as a proxy for it you always pick up the covariance of the two variables in the regression estimator on temperature Second yes even if the omitted is essentially uncorrelated with the included the variation in the omitted could overwhelm the effect one is searching for Positive significance in such cases in the old fashioned kind of spurious correlation correlation that is simply coincidental And that gets back to the worry about data mining which has the proclivity to find just those pure coincidental correlations as easily as ones with a causal basis Martin Ringo Posted Feb 22 2006 at 7 42 PM Permalink Re 27 Yes I was offering the explanation in the sense of the Classical Linear Model i e without serially correlated errors For the case of proxies and temperature where we have serial correlated variables running the Y or X regression without some form of correction be it a full ARMA model or just an old fashioned Cochrane Orcutt iterative rho hat estimator will produce varying degrees of spurious correlation significance However ye old Ordinary Least Squares estimators are still unbiased with first order serial correlation Technical note for those who care unbiased does not mean the expected value of the absolute difference of the estimator and its mean is zero Thus serially correlated variables case say both variables are AR1 will increase the absolute value vis à Æ à vis the null hypothesis of zero effect What OLS estimators have is a much greater variance than the good corrective estimators So ala the Ferson case data mining with amongst serially correlated variables selecting only the positive correlations the data mining when there are serial correlations on both independent and dependent variables the spurious correlation issue will presumably reinforce the omitted variables effect of the same type selection by correlation The magnitude might be kind of interesting to figure out when you get back from the conference on deconstructing reconstructing Paul Linsay Posted Feb 22 2006 at 8 25 PM Permalink 25 It s definitely not a linear relationship and much worse than what you guess If you think about it for a few minutes the relation is more like RW A1 X Y because if the soil is infertile the tree dies if it s too dry the tree dies It s not possible to get that kind of result from a simple linear relationship This whole episode illustrates the trouble people get into when doing a statistical analysis Statistics isn t magic Statistics can t extract information that isn t there Unless there is a prior understanding of the mathematical relation among all the variables affecting a proxy and independent control or measurement of the uninteresting variables there is no way to honestly extract the variable of interest temperature in this case With all the knowledgeable people contributing to this blog I have yet to see any indication that the relation between tree rings density and tree growth factors temperature water sunlight fertility is understood in any quantitative way Wilson s use of low variance is unjustified unless it can be shown a priori that it somehow keeps the uninteresting variables constant Absent that it s just a form of cherry picking applied after the fact to get time series that have the desired correlation with temperature In this context both the Polar Urals and

    Original URL path: http://climateaudit.org/2006/02/22/wilson-on-yamal-substitution/ (2016-02-08)
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  • Jacoby « Climate Audit
    7 2006 9 15 AM Trying to check even simple things like the correlation of individual Osborn and Briffa 2006 series to gridcell temperature always leads to complications Today I ll look at the situation with respect to Jacoby s Sol Dav Mongolia series one of the 6 7 mainstays of Hockey Team reconstructions Needless to say nothing can be confirmed Instead of By Steve McIntyre Also posted in Briffa Esper et al 2002 Jones Mann 2003 Multiproxy Studies Comments 59 Jacoby and D Arrigo Archive Data Apr 12 2006 1 24 PM During the past 20 years Jacoby and D Arrigo had obtained over 45 RW series and at least 35 MXD series in North America To the end of 2005 despite receiivng millions in grants he had only archived a couple of North American RW series and no North American MXD series I discussed this before here By Steve McIntyre Also posted in Proxies Comments 4 A Weird Jacoby D Arrigo Series Apr 8 2006 4 03 PM I mentioned a couple of days ago that Schweingruber et al 1993 seems to arrive at opposite conclusions to Jacoby and D Arrigo 1989 as to whether anomalous post 1950 ring widths occur let alone whether that is due to CO2 fertilization or temperature It was interesting to compare Schweingruber Kienast results at Niwot Ridge It turns out By Steve McIntyre Also posted in Proxies Comments 10 Older posts Tip Jar The Tip Jar is working again via a temporary location Pages About Blog Rules and Road Map CA Assistant CA blog setup Contact Steve Mc Econometric References FAQ 2005 Gridded Data High Resolution Ocean Sediments Hockey Stick Studies Proxy Data Station Data Statistics and R Subscribe to CA Tip Jar Categories Categories Select Category AIT Archiving Nature Science climategate cg2 Data Disclosure and Diligence Peer Review FOIA General Holocene Optimum Hurricane Inquiries Muir Russell IPCC ar5 MBH98 Replication Source Code Spot the Hockey Stick Modeling Hansen Santer UK Met Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel Reply to Huybers Reply to von Storch Blogroll Accuweather Blogs Andrew Revkin Anthony Watts Bishop Hill Bob Tisdale Dan Hughes David Stockwell Icecap Idsos James Annan Jeff Id Josh Halpern Judith Curry Keith

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  • briffa_1995 « Climate Audit
    Studies Also tagged briffa 2000 substitution Yamal Comments 16 More on the Yamal Substitution Feb 21 2006 12 54 PM I wrote recently about the Yamal substitution for the Polar Urals series in both Osborn and Briffa 2006 and D Arrigo et al 2006 This substitution is not incidental as the Yamal version had by far the strongest closing uptick in either data set while the updated Polar Urals ring width series 1998 update had elevated By Steve McIntyre Posted in Briffa D Arrigo 2006 Multiproxy Studies Also tagged briffa 2000 Yamal Comments 4 The Yamal Substitution Feb 12 2006 5 20 PM The Polar Urals temperature reconstruction Briffa et al 1995 has been a mainstay of multiproxy studies More data was collected at this site in 1998 russ176 but in the two new studies Osborn and Briffa 2006 D Arrigo et al 2006 they relate their site selection to the Polar Urals but substitute the Yamal RCS series By Steve McIntyre Posted in Briffa D Arrigo 2006 Multiproxy Studies Also tagged darrigo 2006 osborn briffa 2006 Comments 4 More on Urals and Tornetrask Oct 23 2005 11 02 AM I m finally trying to finalize my presentation on Jones et al 1998 for the US GCRP workshop in November which is necessarily mostly about the Polar Urals and Tornetrask reconstructions Bot MXD chronologies and RW chronologies are supposed to correlate to temperature So an obvious quesiton is how do they correlate to eachother I ve plotted By Steve McIntyre Posted in Briffa Jones et al 1998 Multiproxy Studies Yamal and Urals Also tagged briffa 1992 tornetrask urals Comments 7 Older posts Tip Jar The Tip Jar is working again via a temporary location Pages About Blog Rules and Road Map CA Assistant CA blog setup Contact Steve Mc Econometric References FAQ 2005 Gridded Data High Resolution Ocean Sediments Hockey Stick Studies Proxy Data Station Data Statistics and R Subscribe to CA Tip Jar Categories Categories Select Category AIT Archiving Nature Science climategate cg2 Data Disclosure and Diligence Peer Review FOIA General Holocene Optimum Hurricane Inquiries Muir Russell IPCC ar5 MBH98 Replication Source Code Spot the Hockey Stick Modeling Hansen Santer UK Met Office Multiproxy Studies Briffa Crowley D Arrigo 2006 Esper et al 2002 Hansen Hegerl 2006 Jones Mann 2003 Jones et al 1998 Juckes et al 2006 Kaufman 2009 Loehle 2007 Loehle 2008 Mann et al 2007 Mann et al 2008 Mann et al 2009 Marcott 2013 Moberg 2005 pages2k Trouet 2009 Wahl and Ammann News and Commentary MM Proxies Almagre Antarctica bristlecones Divergence Geological Ice core Jacoby Mann PC1 Medieval Noamer Treeline Ocean sediment Post 1980 Proxies Solar Speleothem Thompson Yamal and Urals Reports Barton Committee NAS Panel Satellite and gridcell Scripts Sea Ice Sea Level Rise Statistics Multivariate RegEM Spurious Steig at al 2009 Surface Record CRU GISTEMP GISTEMP Replication Jones et al 1990 SST Steig at al 2009 UHI TGGWS Uncategorized Unthreaded Articles CCSP Workshop Nov05 McIntyre McKitrick 2003 MM05 GRL MM05 EE NAS Panel

    Original URL path: http://climateaudit.org/tag/briffa_1995/ (2016-02-08)
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