MANN'S COMMENTS TO DAVID APPELL - OCT. 2003
These were copied from www.davidappell.com
in November 2003 after publication of MM03.
10/29/2003: "E&E paper is 'wrong'"
The McIntye and McKitrick ("M&M") Energy and
criticizing the work of Mann, Bradley, and Hughes is wrong, says
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.
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
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: 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
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 ftp://eclogite.geo.umass.edu/pub/mann/ONLINE-PREPRINTS/Millennium/DATA/PROXIES/
(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 http://www.ngdc.noaa.gov/paleo/ei/data_supp.html
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.
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
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
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
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
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
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
And in this case, Soon and Baliunas already collected
all the data for them, didn't they?