Paleoclimate/Hockey Stick

Global Warming: Paleoclimate / Hockey Stick

ACADEMIC PAPERS

PROXY INCONSISTENCY
In 2009, Steve McIntyre and I published a letter in Proceedings of the National Academy of Sciences arguing that a recent paleoclimate reconstruction by Mann et al. does not provide reliable evidence about climate change over the past millennium, because their data are inconsistent and their confidence intervals are wrong.

**McIntyre, Stephen and Ross R. McKitrick (2009) Proxy inconsistency and other problems in millennial paleoclimate reconstructions Proceedings of the National Academy of Sciences February 2, 2009. 106:E10; doi:10.1073/pnas.0812509106

A BRIEF RETROSPECTIVE ON THE HOCKEY STICK:
In Spring 2014 I was invited to contribute a chapter to the Book Climate Change: The Facts, initially published by the Institute for Policy Analysis in Australia, and now by Stockade Books in the US. I was specifically asked if I would discuss the hockey stick episode, and it seemed an appropriate time to survey the story once again. Here is the result.

McKitrick, Ross R. (2014) "A Brief Retrospective on the Hockey Stick" forthcoming in Climate Change: The Facts 2014, Institute for Policy Analysis, Australia.

They wanted it fairly short, which meant it took much longer to write than if they'd asked for a long piece. Often I'd just be finishing the introduction and realize I'd hit the word limit. So naturally it doesn't provide an exhaustive treatment, but the reference list gives the reader plenty of additional leads.

PRESENTATION TO THE NATIONAL ACADEMY OF SCIENCES
This is our 2006 presentation to the NAS Panel investigating the hockey stick and paleoclimate reconstructions generally.

McIntyre, Stephen and Ross McKitrick (2006) Presentation to the National Academy of Sciences on Uncertainties in Paleoclimate Reconstruction

We also submitted some follow-up material based on questions that arose during the meeting.

McIntyre, Stephen and Ross McKitrick (2006) NAS Panel Supplementary Submission
McIntyre, Stephen and Ross McKitrick (2006) NAS Panel Recommendations

M&M CRITIQUE OVERVIEW
The most important scientific paper Steve and I put out was also, probably, the least read:

**McIntyre, Stephen and Ross McKitrick (2005) The M&M Critique of the MBH98 Northern Hemisphere Climate Index: Update and Implications Energy and Environment 16(1) pp. 69-100.

Nothing that appeared in print thereafter added anything of real importance to what was in that paper. Some of the subsequent papers, like Ammann and Wahl’s submission to Climate Change, just re-hashes trivial arguments that were already dealt with in that paper.

HOCKEY STICKS, PRINCIPLE COMPONENTS AND SPURIOUS SIGNIFICANCE
The key paper for cracking open the academic debate on the hockey stick was our 2005 GRL study:

**McIntyre, Stephen and Ross McKitrick (2005) Hockey Sticks, Principal Components and Spurious Significance Geophysical Research LettersVol.
32, No. 3, L03710 10.1029/2004GL021750 12 February 2005.

After its publication two comments were submitted to GRL by Wahl/Ammann and Ritson, both of which were peer-reviewed and rejected (in part because they belabour points already resolved in our E&E paper). Two comments were also submitted by von Storch/Zorita and Huybers, and these were accepted (along with our replies). The von Storch/Zorita one is rather pointless, it merely presents a contrived case in which the PC distortion doesn’t matter. Our reply presented the reasons why their example was irrelevant to understanding the Mann data set, and along the way we present some pretty excruciating findings about how little temperature information is in the Mann data set. Huybers made a legitimate argument about how the RE score should be benchmarked, which prompted us to revise some calculations.

**McIntyre, Stephen and Ross McKitrick (2005) Reply to Comment by von Storch and Zorita on "Hockey Sticks, Principal Components and Spurious Significance" Geophysical Research Letters 32(20) L20714 10.1029/2005GL023089 21 October 2005
**McIntyre, Stephen and Ross McKitrick (2005) Reply to Comment by Huybers on "Hockey Sticks, Principal Components and Spurious Significance" Geophysical Research Letters 32(20) L20714 10.1029/2005GL023586 21 October 2005

We also put out a little backgrounder to explain this exchange in more detail:

Backgrounder

I have included on my pubs list the Materials Complaint we sent in to Nature. Though not a standard journal article, it was reviewed and upheld by the editors of Nature.

**McIntyre, S. and R. McKitrick (2004). Materials Complaint Concerning MBH98 Nature 430 July 1, 2004, p. 105.

M&M 2003: THE PAPER THAT STARTED IT ALL

**McIntyre, Steven and Ross McKitrick, (2003). Corrections to the Mann et al. (1998) Proxy Data Base and Northern Hemisphere Average Temperature Series Environment and Energy 14(6) pp. 751-771.

OTHER

MARCOTT PAPER OP-ED:
I published an op-ed in the Financial Post on April 13 2013 reviewing the unraveling of the Marcott "Hockey Stick" graph.

WHAT IS THE HOCKEY STICK DEBATE ABOUT?
This essay carries the story up to early 2005 when our papers in GRL and E&E had just come out. That was the end of the technical issues, but the process carried on in the form of the expert panel of the US National Academy of Sciences, and the Wegman Committee reports.

McKitrick, Ross R. (2005) What is the Hockey Stick Debate About? Presentation to the Asia Pacific Economic Cooperation Study Centre Meeting on "Managing Climate Change - Practicalities and Realities in a post-Kyoto Future", Parliament House, Canberra Australia, April 4, 2005 (by videolink).

NAS / WEGMAN Op-Eds: In 2006 Steve and I were asked to meet the National Academy of Science panel and make a presentation, whereas the Wegman Committee conducted its work without our input. We also sent a follow-up letter to the NAS Panel after the meetings to deal with some of the unresolved issues during the hearings. I summarized the final outcomes in these op-eds:

NAS Panel Op-ed (National Post July 12, 2006)
Wegman Op-ed: Statisticians Blast Hockey Stick (National Post August 23, 2006)

A well-received essay explaining the early history of the episode, and its implications, is

*McKitrick, Ross R. (2006) The Mann et al. Northern Hemisphere “Hockey Stick” Climate Index: A Tale of Due Diligence in Michaels, Patrick, ed. Shattered Consensus: The TrueState of Global Warming. Rowman and Littlefield, 2006.

In winter 2005 we went to DC and spoke at the National Press Club about our work.

McIntyre, Stephen and Ross. R. McKitrick (2005) The Hockey Stick Debate: Lessons in Disclosure and Due Diligence. Invited Briefing, Washington Roundtable on Science and public Policy, National Press Club, WashingtonDC. Hosted by the Marshall Institute.

YAMAL DATA and the other hockey sticks: I published a column in the National Post on Friday October 2 2009, discussing Steve McIntyre's unraveling of the Yamal paleoclimate data and why it is important. This is of particular historical importance because it was part of the lead-up to Climategate.

CLIMATEGATE TV Special: In August 2010 Fox News did a special on Climategate, which can be viewed here. I appear in the segment beginning at the 20:57 mark.

A large library of related writings is at the

M&M Project Page