Right on cue on the 27th January, this was released:
Canadian Research Showing Flaws in Major Climate Study Profiled in European Science Magazine
Two Canadian researchers, Stephen McIntyre of Toronto and University of Guelph Economics Professor Ross McKitrick, are profiled in the cover story of today’s edition of Natural Science and Technology (Natuurwetenschap & Techniek, or NWT), a prominent European science magazine (see www.natutech.nl). The story focuses on their research forthcoming in the well-known science journals Geophysical Research Letters (pre-publication version at www.climate2003.com/pdfs/2004GL012750.pdf) and Environment and Energy (see www.multiscience.co.uk). NWT reports that the Dutch National Science Foundation (NOW) and the Dutch National Meteorological Agency (KNMI) will convene a special conference within the next month to assess the implications of the findings.
Their research reports on fundamental flaws in the “hockey stick graph†published by Michael Mann of the University of Virginia and his coauthors Raymond Bradley and Malcolm Hughes. The hockey stick was used by the Intergovernmental Panel on Climate Change (IPCC) to claim that the 1990s were the warmest decade of the millennium.
In a statement, McIntyre and McKitrick said: “We identified what appears to be a serious computer programming error in the original calculations. We showed that the principal components analysis (PCA) as used by Mann et al. effectively mines a data set for hockey stick patterns. Even from meaningless random data (red noise), it nearly always produces a hockey stick.†The figure below shows 3 simulations from random data using the MBH method and the published MBH98 temperature reconstruction from proxies. The difficulty in identifying the MBH98 hockey stick illustrates the effect.
Figure 1. Three Simulations from Random Data using MBH98 Method and the MBH98 Reconstruction
In the NWT article, Professor Hans von Storch, an IPCC Contributing Author and internationally-renowned expert in climate statistics at the Center for Coastal Research in Geesthacht, Germany, is quoted as saying that this criticism by McIntyre and McKitrick is “entirely valid.†Dr Mia Hubert, a statistician at the Katholieke Universiteit Leuven in Belgium, agreed, saying: “Tree rings with a hockey stick shape dominate the PCA with this method.â€
Professor Richard Muller of the University of California at Berkeley examined the research last fall, and in an essay published in the MIT Technology Review http://www.technologyreview.com/articles/04/10/wo_muller101504.asp , said the findings “hit me like a bombshell, and I suspect it is having the same effect on many others. ..Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken…This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not…The net result: the “principal component†will have a hockey stick shape even if most of the data do not. “
McIntyre and McKitrick added: “We also found that the original study erred in only applying one statistical test for significance and that the benchmarks for this one test were incorrectly calculated. If a second standard test had been also applied and/or if the benchmarks had been correctly calculated, it would have shown that the results lack statistical significance. “
“We found that the distinctive hockey stick shape of MBH98 was simply an imprint of a strong 20th century growth spurt from a group of bristlecone pine trees in the western USA. The original authors of this data stated that this growth was not due to temperature and MBH co-author Hughes has said elsewhere that the high 20th century bristlecone pine growth is a ‘mystery’. But their unusual shape dominates the final results both in the original MBH98 study and invarious new attempts by Mann et al. to salvage MBH98-type results. We also found that Mann et al. had made unreported ad hoc editing of one series which affected 15th century results.â€
“When we repeated MBH98 calculations (1) using the archived version of the Gaspé tree ring series rather than the version with ad hoc editing by Mann et al.; (2) using exactly the same number of series as MBH98, but with standard centered PC calculations rather than the data mining method of MBH98, we obtained high early 15th century results (similar to those reported in an earlier article using somewhat different methodology), as shown in the Figure below. But ee emphasize that neither reconstruction has any statistical significance.â€
Figure 2. Northern Hemisphere Temperature Reconstructions using MBH98-type methodology and MBH98 indicator rosters: bold - using centered PC calculations and archived Gaspé data; grey - MBH98.
IPCC Lead Author Dr. Rob van Dorland, a climate scientist at KNMI, is quoted saying that McIntyre and McKitrick’s research will “seriously damage the image of the IPCC.†He added: “It is strange that the climate reconstruction of Mann has passed both peer review rounds of the IPCC without anyone ever really having checked it. I think this issue will be on the agenda of the next IPCC meeting in Peking this May.â€
For information, including background materials and contact details, please consult the websites www.climate2003.com and http://www.uoguelph.ca/~rmckitri/research/trc.html.
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Let the denying begin!
Canadian Research Showing Flaws in Major Climate Study Profiled in European Science Magazine
Two Canadian researchers, Stephen McIntyre of Toronto and University of Guelph Economics Professor Ross McKitrick, are profiled in the cover story of today’s edition of Natural Science and Technology (Natuurwetenschap & Techniek, or NWT), a prominent European science magazine (see www.natutech.nl). The story focuses on their research forthcoming in the well-known science journals Geophysical Research Letters (pre-publication version at www.climate2003.com/pdfs/2004GL012750.pdf) and Environment and Energy (see www.multiscience.co.uk). NWT reports that the Dutch National Science Foundation (NOW) and the Dutch National Meteorological Agency (KNMI) will convene a special conference within the next month to assess the implications of the findings.
Their research reports on fundamental flaws in the “hockey stick graph†published by Michael Mann of the University of Virginia and his coauthors Raymond Bradley and Malcolm Hughes. The hockey stick was used by the Intergovernmental Panel on Climate Change (IPCC) to claim that the 1990s were the warmest decade of the millennium.
In a statement, McIntyre and McKitrick said: “We identified what appears to be a serious computer programming error in the original calculations. We showed that the principal components analysis (PCA) as used by Mann et al. effectively mines a data set for hockey stick patterns. Even from meaningless random data (red noise), it nearly always produces a hockey stick.†The figure below shows 3 simulations from random data using the MBH method and the published MBH98 temperature reconstruction from proxies. The difficulty in identifying the MBH98 hockey stick illustrates the effect.
Figure 1. Three Simulations from Random Data using MBH98 Method and the MBH98 Reconstruction
In the NWT article, Professor Hans von Storch, an IPCC Contributing Author and internationally-renowned expert in climate statistics at the Center for Coastal Research in Geesthacht, Germany, is quoted as saying that this criticism by McIntyre and McKitrick is “entirely valid.†Dr Mia Hubert, a statistician at the Katholieke Universiteit Leuven in Belgium, agreed, saying: “Tree rings with a hockey stick shape dominate the PCA with this method.â€
Professor Richard Muller of the University of California at Berkeley examined the research last fall, and in an essay published in the MIT Technology Review http://www.technologyreview.com/articles/04/10/wo_muller101504.asp , said the findings “hit me like a bombshell, and I suspect it is having the same effect on many others. ..Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken…This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not…The net result: the “principal component†will have a hockey stick shape even if most of the data do not. “
McIntyre and McKitrick added: “We also found that the original study erred in only applying one statistical test for significance and that the benchmarks for this one test were incorrectly calculated. If a second standard test had been also applied and/or if the benchmarks had been correctly calculated, it would have shown that the results lack statistical significance. “
“We found that the distinctive hockey stick shape of MBH98 was simply an imprint of a strong 20th century growth spurt from a group of bristlecone pine trees in the western USA. The original authors of this data stated that this growth was not due to temperature and MBH co-author Hughes has said elsewhere that the high 20th century bristlecone pine growth is a ‘mystery’. But their unusual shape dominates the final results both in the original MBH98 study and invarious new attempts by Mann et al. to salvage MBH98-type results. We also found that Mann et al. had made unreported ad hoc editing of one series which affected 15th century results.â€
“When we repeated MBH98 calculations (1) using the archived version of the Gaspé tree ring series rather than the version with ad hoc editing by Mann et al.; (2) using exactly the same number of series as MBH98, but with standard centered PC calculations rather than the data mining method of MBH98, we obtained high early 15th century results (similar to those reported in an earlier article using somewhat different methodology), as shown in the Figure below. But ee emphasize that neither reconstruction has any statistical significance.â€
Figure 2. Northern Hemisphere Temperature Reconstructions using MBH98-type methodology and MBH98 indicator rosters: bold - using centered PC calculations and archived Gaspé data; grey - MBH98.
IPCC Lead Author Dr. Rob van Dorland, a climate scientist at KNMI, is quoted saying that McIntyre and McKitrick’s research will “seriously damage the image of the IPCC.†He added: “It is strange that the climate reconstruction of Mann has passed both peer review rounds of the IPCC without anyone ever really having checked it. I think this issue will be on the agenda of the next IPCC meeting in Peking this May.â€
For information, including background materials and contact details, please consult the websites www.climate2003.com and http://www.uoguelph.ca/~rmckitri/research/trc.html.
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Let the denying begin!
