Comments on: Recent Climate Observations Compared to Predictions by Rahmstorf et.al. – a review http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/ The power of numeracy Mon, 15 Mar 2010 09:48:22 -0500 http://wordpress.org/?v=2.8.6 hourly 1 By: Blog-Reviews « Climate Review http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-121296 Blog-Reviews « Climate Review Tue, 06 May 2008 20:48:01 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-121296 [...] Alle drei vorgestellten Rezensionen bezogen sich auf Paper mit Inhalten, die “Skeptikern” zu Gute kamen. Gegenteiliges - also Skeptiker, die alarmistische Studien auf inhaltlicher Ebene und anhand konkreter Eigenarbeit in Frage stellen - ist sehr selten zu finden. Kürzlich (bei den Recherchen zum Miskolczi-Paper) entdeckte ich allerdings die Seite “Niche Modeling” auf welcher sich der Statistiker Stockwell kritisch mit der Studie “Recent climate observations compared to projections” von Rahmstorf et al. auseinandersetzte. Die Arbeit von Rahmstorf et al. sagte aus, dass fast alle beobachteten Klima-Indikatoren (Meeresspiegel- und Temperaturerhöhung sowie die CO2-Zunahme) am oberen Ende der vom IPCC prognostizierten Werte liegen. In gleich vier Beiträgen (jedes Wort ein Link, Beiträge chronologisch geordnet, beginnend mit dem “ältesten” Artikel) äusserte Dr. Stockwell Kritik zu den von Rahmstorf et al. verwendeten statistischen Verfahren. Erfreulich zu sehen, dass wissenschaftliche Kritik auf Blogs auch von der “anderen” Seite stammen kann. [...] [...] Alle drei vorgestellten Rezensionen bezogen sich auf Paper mit Inhalten, die “Skeptikern” zu Gute kamen. Gegenteiliges – also Skeptiker, die alarmistische Studien auf inhaltlicher Ebene und anhand konkreter Eigenarbeit in Frage stellen – ist sehr selten zu finden. Kürzlich (bei den Recherchen zum Miskolczi-Paper) entdeckte ich allerdings die Seite “Niche Modeling” auf welcher sich der Statistiker Stockwell kritisch mit der Studie “Recent climate observations compared to projections” von Rahmstorf et al. auseinandersetzte. Die Arbeit von Rahmstorf et al. sagte aus, dass fast alle beobachteten Klima-Indikatoren (Meeresspiegel- und Temperaturerhöhung sowie die CO2-Zunahme) am oberen Ende der vom IPCC prognostizierten Werte liegen. In gleich vier Beiträgen (jedes Wort ein Link, Beiträge chronologisch geordnet, beginnend mit dem “ältesten” Artikel) äusserte Dr. Stockwell Kritik zu den von Rahmstorf et al. verwendeten statistischen Verfahren. Erfreulich zu sehen, dass wissenschaftliche Kritik auf Blogs auch von der “anderen” Seite stammen kann. [...]

]]> By: Niche Modeling » Free CO2 for all http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-117758 Niche Modeling » Free CO2 for all Fri, 25 Apr 2008 22:22:29 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-117758 [...] Unlike the models currently used to simulate global warming, the semi-infinite theory suggests very little warming from increases in greenhouse gases, around 0.24C for CO2 doubling. This is because the earth’s atmosphere adjusts for the CO2 by changing the water vapor levels, in order to maintain a constant level of greenhouse effect. If correct, there would be no concerns for ‘runaway warming’ if the theory is correct. More importantly, the nations could continue their economic development with fossil fuels, producing as much CO2 as they like, and increasing the levels in the atmosphere without any fears of climate catastrophe. Previously, in a post with my initial impressions, that the approach Ferenc was taking was sound. The next question I had was how a theory with constant greenhouse might produce changes in surface temperatures. The result of my ruminations on that will be published in Australian Institute of Geologists (AIG) shortly. Briefly, even though the temperature of the troposphere stays relatively constant, the temperature of the stratosphere could influence the surface temperature. Other ways of influencing surface temperature are changes in emmissivity and albedo. [...] [...] Unlike the models currently used to simulate global warming, the semi-infinite theory suggests very little warming from increases in greenhouse gases, around 0.24C for CO2 doubling. This is because the earth’s atmosphere adjusts for the CO2 by changing the water vapor levels, in order to maintain a constant level of greenhouse effect. If correct, there would be no concerns for ‘runaway warming’ if the theory is correct. More importantly, the nations could continue their economic development with fossil fuels, producing as much CO2 as they like, and increasing the levels in the atmosphere without any fears of climate catastrophe. Previously, in a post with my initial impressions, that the approach Ferenc was taking was sound. The next question I had was how a theory with constant greenhouse might produce changes in surface temperatures. The result of my ruminations on that will be published in Australian Institute of Geologists (AIG) shortly. Briefly, even though the temperature of the troposphere stays relatively constant, the temperature of the stratosphere could influence the surface temperature. Other ways of influencing surface temperature are changes in emmissivity and albedo. [...]

]]> By: Niche Modeling » Rahmstorf et al. 2007 IPCC Error? http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-109418 Niche Modeling » Rahmstorf et al. 2007 IPCC Error? Wed, 09 Apr 2008 20:55:47 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-109418 [...] As previously reported here, the conclusions of Rahmstorf’s 7 (Rahmstorf, Cazenave, Church, Hansen, Keeling, Parker, and Somerville) rely on a trend line lying above the IPCC projections on their Figure 1, shown enlarged below. No statistical tests are performed, the basis for their claim is purely based on the visual aid. Their Figure 1 is below, with the key part of the image containing the IPCC projection enlarged. Figures 1 and 2: Rahmstorf et al. (2007) Figure 1. Whole and enlarged. Rahmstorf’s 7 state in the figure caption that “All trends are nonlinear trend lines and are computed with an embedding period of 11 years and a minimum roughness criterion at the end (Moore et.al. 2006 [2])”. On reading Moore’s paper, it would appear the nonlinear methodology used was Singular Spectrum Analysis (SSA). The Moore paper suggests the minimum roughness criterion (MRC) would follow the Mann 2004 [3] recipe of padding the end of the series with data reflected about the final value. Figure 3 and 4: GISS temperature with SSA trend, unpadded and padded. The peculiar property of MRC of “pinning” the trend line to the final end point of the series has been noted in a post “Mannomatic Smoothing and Pinned End-points” at ClimateAudit. The comparison of MRC and non-MRC padded series is shown in figures captured from CaterpillarSSA. The first figure “unpadded.png” shows a SSA trend line that approximates the Rahmstorf figure result. The second figure “padded.png” shows the SSA trend line with an MRC padded GISS series, passing directly through the 2006 value. This is as it should be, as the MRC effectively ‘pins’ the trend line to the final value due to the symmetry about the final value. Was a direct application of the SSA trend line used and not an MRC padded series as described? If an MRC padded series had been used in the figure, it would have been end-pinned to the 2006 value, at the center of the IPCC projections. The figure would then not have conveyed the impression that temperatures are in the upper range of the IPCC projections, as claimed. As it was in 2006, it appears that SSA without MRC padding produces a higher trend line than with MRC padding, necessary for supporting their claim. An additional puzzling factor is the reference to MRC padding at all. Padding the end of the series is not actually necessary to ensure a SSA trend line is drawn to the end of the series values. Padding is only necessary in acausal filters such as moving averages that stop a window length short of the end of the series. To date, attempts to contact Prof. Rahmstorf and clarify the actual methodology used have been unsuccessful. [...] [...] As previously reported here, the conclusions of Rahmstorf’s 7 (Rahmstorf, Cazenave, Church, Hansen, Keeling, Parker, and Somerville) rely on a trend line lying above the IPCC projections on their Figure 1, shown enlarged below. No statistical tests are performed, the basis for their claim is purely based on the visual aid. Their Figure 1 is below, with the key part of the image containing the IPCC projection enlarged. Figures 1 and 2: Rahmstorf et al. (2007) Figure 1. Whole and enlarged. Rahmstorf’s 7 state in the figure caption that “All trends are nonlinear trend lines and are computed with an embedding period of 11 years and a minimum roughness criterion at the end (Moore et.al. 2006 [2])”. On reading Moore’s paper, it would appear the nonlinear methodology used was Singular Spectrum Analysis (SSA). The Moore paper suggests the minimum roughness criterion (MRC) would follow the Mann 2004 [3] recipe of padding the end of the series with data reflected about the final value. Figure 3 and 4: GISS temperature with SSA trend, unpadded and padded. The peculiar property of MRC of “pinning” the trend line to the final end point of the series has been noted in a post “Mannomatic Smoothing and Pinned End-points” at ClimateAudit. The comparison of MRC and non-MRC padded series is shown in figures captured from CaterpillarSSA. The first figure “unpadded.png” shows a SSA trend line that approximates the Rahmstorf figure result. The second figure “padded.png” shows the SSA trend line with an MRC padded GISS series, passing directly through the 2006 value. This is as it should be, as the MRC effectively ‘pins’ the trend line to the final value due to the symmetry about the final value. Was a direct application of the SSA trend line used and not an MRC padded series as described? If an MRC padded series had been used in the figure, it would have been end-pinned to the 2006 value, at the center of the IPCC projections. The figure would then not have conveyed the impression that temperatures are in the upper range of the IPCC projections, as claimed. As it was in 2006, it appears that SSA without MRC padding produces a higher trend line than with MRC padding, necessary for supporting their claim. An additional puzzling factor is the reference to MRC padding at all. Padding the end of the series is not actually necessary to ensure a SSA trend line is drawn to the end of the series values. Padding is only necessary in acausal filters such as moving averages that stop a window length short of the end of the series. To date, attempts to contact Prof. Rahmstorf and clarify the actual methodology used have been unsuccessful. [...]

]]> By: Ian Castles http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-103728 Ian Castles Wed, 02 Apr 2008 03:02:28 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-103728 The 11 members of the SSA-MTM Group, as listed in Steve McIntyre's post above, are also the 11 co-authors of Ghil et al (2002), 'Advanced spectral methods for climatic time series', Reviews of Geophysics, 40, DOI 10.1029/2001RG000092. Thus, Rahmstorf et al (2007) cited Moore et al (2005), which in turn cited Ghil et al (2002) - and, for the 'minimum roughness criterion', Mann (2004). The 11 members of the SSA-MTM Group, as listed in Steve McIntyre’s post above, are also the 11 co-authors of Ghil et al (2002), ‘Advanced spectral methods for climatic time series’, Reviews of Geophysics, 40, DOI 10.1029/2001RG000092. Thus, Rahmstorf et al (2007) cited Moore et al (2005), which in turn cited Ghil et al (2002) – and, for the ‘minimum roughness criterion’, Mann (2004).

]]> By: admin http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-103634 admin Tue, 01 Apr 2008 21:55:28 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-103634 Hi Steve, Yes I have used it now. Its a neat technique particularly with mixed trends and periodic signals. However, total overkill to use it to trend the last 20 years of temperatures ala Rahmsdorf etal, where a linear trend or cubic spline is more than adequate. Hi Steve, Yes I have used it now. Its a neat technique particularly with mixed trends and periodic signals. However, total overkill to use it to trend the last 20 years of temperatures ala Rahmsdorf etal, where a linear trend or cubic spline is more than adequate.

]]> By: Steve McIntyre http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-103626 Steve McIntyre Tue, 01 Apr 2008 21:28:04 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-103626 David, you can locate the SSA "toolkit" here: http://www.atmos.ucla.edu/tcd/ssa/ The toolkit is described: <blockquote>The SSA-MTM Toolkit is a product of the SSA-MTM Group (so far: Myles Allen, Mike Dettinger, Kayo Ide, Dmitri Kondrashov, Michael Ghil, Mike Mann, Andrew W. Robertson, Amira Saunders, Ferenc Varadi, Yudong Tian, and Pascal Yiou) at UCLA (mostly). You can direct comments on installation and performance, as well as suggestions for future versions, to ssahelp@atmos.ucla.edu.</blockquote> All that appears to be involved is a SVD/principal components analysis of the autocovariance matrix. The MTM part appears to be a SVD/principal components analysis of the spectrum - and this was Mann's specialty prior to MBH. David, you can locate the SSA “toolkit” here: http://www.atmos.ucla.edu/tcd/ssa/ The toolkit is described:

The SSA-MTM Toolkit is a product of the SSA-MTM Group (so far: Myles Allen, Mike Dettinger, Kayo Ide, Dmitri Kondrashov, Michael Ghil, Mike Mann, Andrew W. Robertson, Amira Saunders, Ferenc Varadi, Yudong Tian, and Pascal Yiou) at UCLA (mostly). You can direct comments on installation and performance, as well as suggestions for future versions, to ssahelp@atmos.ucla.edu.

All that appears to be involved is a SVD/principal components analysis of the autocovariance matrix. The MTM part appears to be a SVD/principal components analysis of the spectrum – and this was Mann’s specialty prior to MBH.

]]> By: Ian Castles http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-102254 Ian Castles Sat, 29 Mar 2008 02:20:39 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-102254 When the Garnaut review claims not to have the time or resources 'to adjudicate on the relative merits of various expert scientific opinions', I don't think that it occurs to them that the study by Rahmstorf et al of 'Recent Climate Observations Compared to Projections' is anything other than a routine reporting of results using standard and well-accepted statistical methods. If the late (and sadly missed) Chris Heyde was still with us, I would certainly be seeking his views on the statistical methods underpinning the Rahmstorf study. Surely there are other statisticians with the time and interest to set Garnaut straight on this matter? When the Garnaut review claims not to have the time or resources ‘to adjudicate on the relative merits of various expert scientific opinions’, I don’t think that it occurs to them that the study by Rahmstorf et al of ‘Recent Climate Observations Compared to Projections’ is anything other than a routine reporting of results using standard and well-accepted statistical methods.

If the late (and sadly missed) Chris Heyde was still with us, I would certainly be seeking his views on the statistical methods underpinning the Rahmstorf study. Surely there are other statisticians with the time and interest to set Garnaut straight on this matter?

]]> By: Peter Gallagher http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-101970 Peter Gallagher Fri, 28 Mar 2008 10:29:22 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-101970 David, Like you (and Ian Castles) I am really puzzled that Ross Garnaut, whom I have known for 30 years as a professional analyst, would hang his case so heavily on a brief piece of advocacy (Rhamstorf et al). Thank you for your insights into the 'padding' of the Rhamstorf series. I had not bothered to read the Moore paper. Best wishes Peter David,

Like you (and Ian Castles) I am really puzzled that Ross Garnaut, whom I have known for 30 years as a professional analyst, would hang his case so heavily on a brief piece of advocacy (Rhamstorf et al).

Thank you for your insights into the ‘padding’ of the Rhamstorf series. I had not bothered to read the Moore paper.

Best wishes

Peter

]]> By: admin http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-101814 admin Thu, 27 Mar 2008 22:40:54 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-101814 Lucia, I would have to look up the SD, which would be a SD of a temperature 'estimate' at a given year. As the SD at the start point SD_1 and the slope SD_2 are then independent, the variances should add to SD_o. So the overall error should then be SD_o = sqr(SD_1^2+SD_2^2). Lucia, I would have to look up the SD, which would be a SD of a temperature ‘estimate’ at a given year. As the SD at the start point SD_1 and the slope SD_2 are then independent, the variances should add to SD_o. So the overall error should then be SD_o = sqr(SD_1^2+SD_2^2).

]]> By: lucia http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/comment-page-1/#comment-101731 lucia Thu, 27 Mar 2008 18:19:37 +0000 http://landshape.org/enm/recent-climate-observations-compared-to-predictions-by-rahmstorf-etal-a-review/#comment-101731 David-- Out of curiosity, can you get an uncertainty estimate for the "true mean" near 1990? The reason I ask is the procedure in Rahmstorf is to rebaseline (that is shift) all the temperatures to the "mean" temperature at 1990. (The TAR just sets the baseline at 1990 to zero, and includes no data. So, you see, it's set to the entirely unknown and unknowable "true mean temperature" for 1990.) To do the eyeball method of data analysis, Rahmstorf finds one specific temperature, then shift the whole shebang up. No uncertainty is attributed to the shift. However, if I were to say the 95% uncertainty in the mean was 0.1C or so, (as consistent with estimating based on a 11 year centered mean) and shift up or down a different amount, we get different results using the "calibrated eyeball test" used in Rahmstorf. David–
Out of curiosity, can you get an uncertainty estimate for the “true mean” near 1990?

The reason I ask is the procedure in Rahmstorf is to rebaseline (that is shift) all the temperatures to the “mean” temperature at 1990. (The TAR just sets the baseline at 1990 to zero, and includes no data. So, you see, it’s set to the entirely unknown and unknowable “true mean temperature” for 1990.)

To do the eyeball method of data analysis, Rahmstorf finds one specific temperature, then shift the whole shebang up. No uncertainty is attributed to the shift. However, if I were to say the 95% uncertainty in the mean was 0.1C or so, (as consistent with estimating based on a 11 year centered mean) and shift up or down a different amount, we get different results using the “calibrated eyeball test” used in Rahmstorf.

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