These were copied from in November 2003 after publication of MM03.

10/29/2003: "E&E paper is 'wrong'"

The McIntye and McKitrick ("M&M") Energy and Environment paper criticizing the work of Mann, Bradley, and Hughes is wrong, says Mann.

In short, here's what happened: M&M asked an associate of Mann to supply them with the Mann et. al. proxy data in an Excel spreadsheet, even though the raw data is available here. An error was made in preparing this Excel file, in which the early series were successively overprinted by later and later series, and this is the data M&M used. Mann says:

"...the authors results are entirely spurious. The mistake made insures that the estimates, in particular prior to 1600-1700, are meaningless."
This leads, Mann says, to "the use of series that are artificial combinations of early [e.g. 15th-16th century] and late [e.g. 19th-20th] information accidentally spliced together" with "no relation" to the proxy data used by Mann et. al. in their 1998 (and subsequent) work.

Mann adds:
The spreadsheet file they used was a complete distortion of the actual Mann et. al. proxy data set, and was essentially useless, particularly in the earlier centuries. The authors had access to the full data, which has been available on a public ftp site for nearly two years. When they noticed, as described in their paper, some signs of problems with the Excel spreadsheet version of the data, one might think that they would have bothered to check the data available on our public ftp site.

10/29/2003: "M&M: The Details"

Apparently Mann had told McIntyre last April that his raw data were available on his FTP site, according to this email (shared with permission):

Date: Wed, 09 Apr 2003 05:58:29 -0400
To: Steve McIntyre
From: "Michael E. Mann"
Subject: Re: Proxies in MBH
Cc: Scott Rutherford

Dear Mr. McIntyre,

These data are available on an anonymous ftp site we have set up. I've forgotten the exact location, but I've asked my Colleague Dr. Scott Rutherford if he can provide you with that information.

best regards,

Mike Mann
At 01:47 PM 4/8/2003 -0400, Steve McIntyre wrote:

Dear Dr. Mann,

I have been studying MBH98 and 99. I located datasets for the 13 series used in 99 at (the convenience of the ftp: location being excellent) and was intereseted in locating similar information on the 112 proxies referred to in MBH98, as well as listing (the listing at is for 390 datasets, and I gather/presume that many of these listed datasets have been condensed into PCs, as mentioned in the paper itself. Thank you for your attention.

Yours truly,

Stephen McIntyre,
Toronto, Canada
This quickly gets into some hairy details, but Mann says that the crux of M&M's error is their use of a Excel dataset with only 112 columns (where each column represents one set of proxy data--tree rings, ice cores, historical temperature data, etc.), when in fact the full paleoclimatic data series requires 159 to be used properly in the analysis behind the Mann, Bradley, and Hughes 1998 paper whose results they're trying to check.

This email indicates that M&M were at least initially aware of this, and could have used raw data if they'd chosen.

10/29/2003: "M&M (&M), Take 2"

I though I'd try and summarize the M&M situation as of tonight.

In 1998 Michael Mann, Ray Bradley, and Malcolm Hughes published the now-famous "hockey stick" view of global warming in Nature magazine, in which Northern Hemisphere temperatures rise significantly in the late-20th century to the extent that they're the warmest in the last thousand years. This is probably one of the most important scientific findings of the '90s, and it (and, as always, work preceding and following it) has played a significant role in concerns about anthropogenic global warming.

Harvard researchers Willie Soon and Sallie Baliunas took a shot at this conclusion this spring--which is known in the profession as "MBH98"--publishing in the journals Climate Research and Energy and Environment. Soon and Baliunas's paper came away in tatters, discredited on methodological grounds. In protest of the peer-review process that allowed publication of the paper in Climate Research, six of the journal's editorial advisors resigned, including its new editor-in-chief.

This Monday, Canadians Steven McIntyre (a mining executive) and Ross McKitrick (an economics professor) came next up to bat, publishing a paper in the same Energy and Environment with the provocative title "Errors and Defects in Mann et. al. (1998) Proxy Data and Temperature History." McIntyre and McKitrick ("M&M") said that they had tried to reproduce MBH's results using MBH's data--a classic case of scientific double-checking--and had found a different answer. Instead of confirming MBH's 1998 results, M&M said that mid-millenium temperatures were, by their analysis, higher than late 20th century temperatures--that is, that MBH were wrong, and that, arguably, the temperatures now being measured around the world are not dangerously high because they are purportedly lower than those during the Middle Ages.

M&M apparently did not start from MBH's raw data--which consists of 2,077 different files--but instead asked Michael Mann to provide them with an Excel spreadsheet of summarized and collated data. Mann and a colleague who was assisting him indicated to M&M that they could obtain their raw data via FTP on the Web, and also did their best to provide the data in the format requested.

However, Mann said today, a transcription error was inadvertently made in preparation of the spreadsheet, in which some multiple data that should have appeared in multiple columns was mistakenly overwritten into some single columns. A dataset that should have contained 159 columns of data in fact only contained 112 columns. So when M&M slid this dataset into their calculations, the results that came out were naturally in error.

Garbage in, garbage out.

M&M have published their paper, strongly claiming that MBH "contains collation errors, unjustifiable truncation or extrapolation of source data, obsolete data, geographical location errors, incorrect calculation of principal components and other quality control defects."

Nick Schulz, editor of TechCentral Station, today published an Op-Ed championing M&M's results in which USA Today; he also mistakenly claimed that the MBH data was not available online. We'll see if he retracts at least the last claim.

James Glassman, who in an earlier lifetime famously predicted that the Dow Jones Industrial Average would someday soon hit 36,000 and whom for some unknownable reason people still take even the slightest bit seriously, also championed M&M today on TechCentral Station. But what's another turd on an already impressive pile of shit?

More on these technical mistakes will come out in the near future, I hear. I have asked McIntyre and McKitrick if they had checked the data they received from Mann and associate against MBH's raw data, as you'd think you would if you were truly trying to double- and triple-check an important established scientific conclusion (especially if you were going to seriously slam it), but haven't received a reply.

I have also asked Sonia Boehmer-Christiansen, the self-professed politically biased editor of Energy and Environment, if her reviewers of the paper had done the same, but have not received a reply from her, either. This appears to be the second highly charged, politically motivated, and scientifically dubious paper her journal has published in the last six months, a path to irrelevancy if there ever was one.

Hope that clears things up a little. More as things develop.

10/30/2003: "M&M respond"

McIntyre and McKitrick have responded to Mann's claims here. It's laid out in great detail, though they say there are not sufficient details on the table yet for a full response. (As I understand it these details are being prepared, but I have no idea when or where they'll appear.)

M&M do say "We did not ask for an Excel spreadsheet nor did we receive one, and we did not approach Mann's associate, Mann did." This could well be semantics; the data given to M&M is here (note, it has 112 columns), in a tabular format.

The rest of M&M's response speaks for itself.

As I wrote earlier, the details of both the calculation and the correspondence are quite hairy. Some of M&M's questions seem like a graduate student exercise in linear algebra; it still seems to me that a true replication effort, especially for publication, should entail using original, raw data that you gather yourself without replying on anyone to massage for you--otherwise to know exactly what you're getting (even if someone does their best to try and tell you). For example, in particle physics it's usually two or more groups who have independently done experiments--at great effort and expense--to discover and verify particles such as quarks and gauge bosons. OK, OK, these are huge expensive experiments, but you get my point: one group doesn't ask the other for their data and then recrunches the numbers, but collects their own data and goes from there.

And in this case, Soon and Baliunas already collected all the data for them, didn't they?