Geophysical Research Letters

Volume 32, Issue 20

Climate

Free Access

Comment on “Hockey sticks, principal components, and spurious significance” by S. McIntyre and R. McKitrick

P. Huybers

E-mail address:phuybers@mit.edu

Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA

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P. Huybers

E-mail address:phuybers@mit.edu

Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA

Search for more papers by this author

First published: 21 October 2005

https://doi.org/10.1029/2005GL023395

Cited by: 8

This is a commentary on DOI:10.1029/2004GL021750

Number of times cited: 8

Jason E. Smerdon and Henry N. Pollack, Reconstructing Earth's surface temperature over the past 2000 years: the science behind the headlines, Wiley Interdisciplinary Reviews: Climate Change, 7, 5, (746-771), (2016).
MAXIM G. OGURTSOV, HOGNE JUNGNER, SAMULI HELAMA, MARKUS LINDHOLM and MARKKU OINONEN, PALEOCLIMATOLOGICAL EVIDENCE FOR UNPRECEDENTED RECENT TEMPERATURE RISE AT THE EXTRATROPICAL PART OF THE NORTHERN HEMISPHERE, "Geografiska Annaler: Series A, Physical Geography", 93, 1, (17-26), (2011).
Jason E. Smerdon, Alexey Kaplan, Diana Chang and Michael N. Evans, A Pseudoproxy Evaluation of the CCA and RegEM Methods for Reconstructing Climate Fields of the Last Millennium*, Journal of Climate, 24, 4, (1284)
Crossref
Jason E. Smerdon, Alexey Kaplan, Diana Chang and Michael N. Evans, A Pseudoproxy Evaluation of the CCA and RegEM Methods for Reconstructing Climate Fields of the Last Millennium*, Journal of Climate, 23, 18, (4856)
Crossref
Paul R. Sheppard, Dendroclimatology: extracting climate from trees, Wiley Interdisciplinary Reviews: Climate Change, 1, 3, (343-352), (2010).
Michael E. Mann, Scott Rutherford, Eugene Wahl and Caspar Ammann, Robustness of proxy‐based climate field reconstruction methods, Journal of Geophysical Research: Atmospheres, 112, D12, (2007).
Caspar M. Ammann and Eugene R. Wahl, The importance of the geophysical context in statistical evaluations of climate reconstruction procedures, Climatic Change, 85, 1-2, (71)
Crossref
Stephen McIntyre and Ross McKitrick, Reply to comment by Huybers on “Hockey sticks, principal components, and spurious significance”, Geophysical Research Letters, 32, 20, (2005).

Supporting Information

Auxiliary material for this article contains files and data that permit reproduction of the results and figures presented in the comment.

Filename	Description
grl20096-sup-0001-README.txtplain text document, 3.4 KB	README.txt
grl20096-sup-0002-pca.m.txtplain text document, 3.9 KB	pca.m.txt
grl20096-sup-0003-Rscript.R.txtplain text document, 24.3 KB	Rscript.R.txt
grl20096-sup-0004-Monte_Carlo_RE.m.txtplain text document, 2.3 KB	Monte_Carlo_RE.m.txt
grl20096-sup-0005-NOAMER.m.txtplain text document, 239.5 KB	NOAMER.m.txt
grl20096-sup-0006-NH_Temperature.m.txtplain text document, 28.4 KB	NH_Temperature.m.txt
grl20096-sup-0007-Instrumental_Sparse.m.txtplain text document, 7.7 KB	Instrumental_Sparse.m.txt
grl20096-sup-0008-xcPH.m.txtplain text document, 1.1 KB	xcPH.m.txt
grl20096-sup-0009-rePH.m.txtplain text document, 282 B	rePH.m.txt
grl20096-sup-0010-phaserandomize.m.txtplain text document, 355 B	phaserandomize.m.txt
grl20096-sup-0011-smoothPH.m.txtplain text document, 648 B	smoothPH.m.txt
grl20096-sup-0011-pca.m.txtplain text document, 3.9 KB	text 1. Matlab script that normalizes the NOAMER data‐set according to the MBH98, MM05, and fully normalized conventions. PCs and averages of the normalized data‐set are computed and the figures included in the comment are generated.
grl20096-sup-0012-Rscript.R.txtplain text document, 24.3 KB	text 2. Modified version of the R script used by MM05 to produce figures and to estimate RE critical values and other statistic. All modification are annotated and described in the code using the format “#PH, …”. The original code omits a crucial normalization step when computing realizations of the RE statistic. The modified code now computes RE values both as originally done by MM05 and with the correct normalization step — the latter results are referred to in the code as “REfix”. To get this code to run on your machine you will need to change the temp.directory on line 226 to a directory local to your computer. To download and install the R software see www.r-project.org. Note you will also need to have the waveslim package installed. Binaries for the waveslim package used by MM05 are only pre‐compiled for Windows machines.
grl20096-sup-0013-Monte_Carlo_RE.m.txtplain text document, 2.3 KB	text 3. A simple Matlab example illustrating the discrepancy in MM05's estimate of the RE critical value.
grl20096-sup-0014-NOAMER.m.txtplain text document, 239.5 KB	text 4. The seventy North American tree ring records originally catalogued as auxiliary material by MM05. The records are identical with those used by MBH98. Slight modifications are made to the file so that it is Matlab readable.
grl20096-sup-0015-NH_Temperature.m.txtplain text document, 28.4 KB	text 5. Matlab readable version of the updated instrumental Northern Hemisphere Temperature estimate from from Jones and Moberg [2003]. See the file for full references.
grl20096-sup-0016-Instrumental_Sparse.m.txtplain text document, 7.7 KB	text 6. Matlab readable version of the Northern Hemisphere temperature records used by MBH98 and MM05 for calibration and verification.
grl20096-sup-0017-xcPH.m.txtplain text document, 1.1 KB	text 7. Supporting Matlab function to calculate the cross‐correlation.
grl20096-sup-0018-rePH.m.txtplain text document, 282 B	text 8. Supporting Matlab function to calculate the reduction in error statistic.
grl20096-sup-0019-phaserandomize.m.txtplain text document, 355 B	text 9. Supporting Matlab function to generate random records with an auto‐correlation structure similar to the input record.
grl20096-sup-0020-smoothPH.m.txtplain text document, 648 B	text 10. Supporting Matlab function to smooth a vector.