Tuesday, November 29, 2011


cc: Stephen Schneider <shsatXYZxyznford.edu>, Gavin Schmidt <gschmidtatXYZxyzs.nasa.gov>, Stefan Rahmstorf <rahmstorfatXYZxyzan-klima.de>, Phil Jones <p.jonesatXYZxyz.ac.uk>, Tim Osborn <t.osbornatXYZxyz.ac.uk>, Andy Revkin <anrevkatXYZxyzimes.com>, Henry Pollack <hpollackatXYZxyzch.edu>, Gabi Hegerl <gabi.hegerlatXYZxyzac.uk>, Benjamin Santer <santer1atXYZxyzl.gov>, Richard Littlemore <quotableatXYZxyzus.net>
date: Fri, 23 Oct 2009 14:15:12 -0400
from: Michael Mann <mannatXYZxyzeo.psu.edu>
subject: Re: From the Wall Street Journal:
to: Anne Jolis <Anne.JolisatXYZxyzjones.com>, Joe Romm <Jromm@americanprogress.org>, Media Matters Erikka Knuti <eknuti@mediamatters.org>, DarkSydOTheMoonatXYZxyz.com, Dan Vergano <dvergano@usatoday.com>, Bud Ward <wardbud@gmail.com>, georgeatXYZxyzbiot.info, AJ Walzer <ajwalzer@mediamatters.org>, "Paul D. Thacker" <pdthackeratXYZxyzoo.com>, Chris Mooney <moonecc@gmail.com>

Dear Anne,

I will respond to these briefly. please see below. Will now be incommunicado through early
next week, so this will have to do.


Mike Mann

On Oct 23, 2009, at 1:12 PM, Jolis, Anne wrote:

Dear Dr. Mann,

I realize you've taken that liberty. I've just sent them all an email as well inviting them
to weigh in (though I've already spoken with Dr. Schneider) - great minds think alike!

I take it that you decline to comment on the two questions I've just resubmitted to you:

-How would you respond to the critique that, as a key part of the review processes of
publications in the field of climate science, as something of a "gatekeeper," you have
rejected and otherwise sought to suppress work that contradicted your work. Is this fair?
Why or why not? How would you characterize your selection process for work that is or is
not worthy of publication?

I won't dignify that question with a response, other than to say that it betrays a deep
naivety about how the peer review process in science works, and it buys into what I
consider to be rather offensive conspiracy theories that impugn the integrity of editors,
reviewers in general, and myself in particular.

-Do you have a response to work published in 2005 by Hans von Storch that seems to indicate
that the predictive capabilities of the method you used in your original "hockey stick"
graph (which I do realize did not use the Yamal data) would not be able to predict current

You seem to be unaware of the fact that there were two serious rebuttals (by Rahmstorf and
by Ritson et al) of the Von Storch claims published subsequently in Science
See the summaries here:
see also what the most recent IPCC report had to say about the hockey stick criticisms:
First, with respect to the McIntyre criticisms so often touted by contrarian disinformation
"The hockey stick reconstruction of Mann et al. (1999) has been the subject of several
critical studies. Soon and Baliunas (2003) challenged the conclusion that the 20th century
was the warmest at a hemispheric average scale. They surveyed regionally diverse proxy
climate data, noting evidence for relatively warm (or cold), or alternatively dry (or wet)
conditions occurring at any time within pre-defined periods assumed to bracket the
so-called Medieval Warm Period (and Little Ice Age). Their qualitative approach precluded
any quantitative summary of the evidence at precise times, limiting the value of their
review as a basis for comparison of the relative magnitude of mean hemispheric 20th-century
warmth (Mann and Jones, 2003; Osborn and Briffa, 2006). Box 6.4 provides more information
on the Medieval Warm Period. McIntyre and McKitrick (2003) reported that they were unable
to replicate the results of Mann et al. (1998). Wahl and Ammann (2007) showed that this was
a consequence of differences in the way McIntyre and McKitrick (2003) had implemented the
method of Mann et al. (1998) and that the original reconstruction could be closely
duplicated using the original proxy data. McIntyre and McKitrick (2005a,b) raised further
concerns about the details of the Mann et al. (1998) method, principally relating to the
independent verification of the reconstruction against 19th-century instrumental
temperature data and to the extraction of the dominant modes of variability present in a
network of western North American tree ring chronologies, using Principal Components
Analysis. The latter may have some theoretical foundation, but Wahl and Amman (2006) also
show that the impact on the amplitude of the final reconstruction is very small (~0.05�C;
for further discussion of these issues see also Huybers, 2005; McIntyre and McKitrick,
2005c,d; von Storch and Zorita, 2005)."
Second, with regard to the Von Storch claims. The IPCC assessment was published prior to
the publication of the two Science refutations of the Von Storch et al paper noted above,
and thus were unable to assess the most serious criticisms of that work. But even at that
point, the IPCC noted some serious caveats about that work, and stressed that even if the
criticisms were valid (which they have been shown not to be), they would not call into
question the key conclusions regarding the anomalous nature of recent warmth in a
millennial+ context:
Using pseudo-proxy networks extracted from GCM simulations of global climate for the last
millennium, von Storch et al. (2004) suggested that temperature reconstructions
may not fully represent variance on long time scales. This would represent a bias, as
distinct from the random error represented by published reconstruction uncertainty ranges.
At present, the extent of any such biases in specific reconstructions and as indicated by
pseudo-proxy studies is uncertain (being dependent on the choice of statistical regression
model and climate model simulation used to provide the pseudo-proxies). It is very
unlikely, however, that any bias would be as large as the factor of two suggested by von
Storch et al. (2004) with regard to the reconstruction by Mann et al. (1998), as
discussed by Burger and Cubash (2005) and Wahl et al. (2006). However,
the bias will depend on the degree to which past climate departs from the range of
temperatures encompassed within the calibration period data (Mann et al., 2005b; Osborn
and Briffa, 2006) and on the proportions of temperature variability occurring on short and
long time scales (Osborn and Briffa, 2004). In any case, this bias would act to damp the
amplitude of reconstructed departures that are further from the calibration period mean, so
that temperatures during cooler periods may have been colder than estimated by some
reconstructions, while periods with comparable temperatures (e.g., possible portions of the
period between AD 950 and 1150, Figure 6.10) would be largely unbiased. As only one
reconstruction (Moberg et al., 2005) shows an early period that is noticeably warmer than
the mean for the calibration period, the possibility of a bias does not affect the general
conclusion about the relative warmth of the 20th century based on these data.
Finally, the summary of the current state of knowledge regarding the anomalous nature of
recent warming, by the IPCC:
The weight of current multi-proxy evidence, therefore, suggests greater 20th-century
warmth, in comparison with temperature levels of the previous 400 years, than was shown in
the TAR. On the evidence of the previous and four new reconstructions that reach back more
than 1 kyr, it is likely that the 20th century was the warmest in at least the past 1.3
kyr. Considering the recent instrumental and longer proxy evidence together, it is very
likely that average NH temperatures during the second half of the 20th century were higher
than for any other 50-year period in the last 500 years.


From: Michael Mann [[4]mailto:mannatXYZxyzeo.psu.edu]
Sent: 23 October 2009 18:07
To: Jolis, Anne; Joe Romm; Media Matters Erikka Knuti; [5]DarkSydOTheMoonatXYZxyz.com; Dan
Vergano; Bud Ward; [6]georgeatXYZxyzbiot.info; AJ Walzer; Paul D. Thacker; Chris Mooney
Cc: Stephen Schneider; Gavin Schmidt; Stefan Rahmstorf; Phil Jones; Tim Osborn; Andy
Revkin; Henry Pollack; Gabi Hegerl; Benjamin Santer; Richard Littlemore
Subject: Re: From the Wall Street Journal:
Ms. Jolis,
I've taken the liberty of copying this exchange to a few others who might be interested in
it, within the broader context of issues related to the history of biased reporting on
climate change at the Wall Street Journal Europe,
Mike Mann
On Oct 23, 2009, at 12:42 PM, Michael Mann wrote:

Ms. Jolis,
I am traveling through this weekend and have only brief email access, so can only respond
w/ a very short email to your inquiry.
I'm sad to report that the tone of your questions suggests a highly distorted,
contrarian-driven view of the entirety of our science. The premise of essentially everyone
of your questions is wrong, and is contradicted by assessments such as the IPCC report,
reports by the U.S. National Academy of Sciences, etc. The National Academy of Science
report (more info below) reported in 2006 that "The basic conclusion of Mann et al. (1998,
1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented
during at least the last 1,000 years. This conclusion has subsequently been supported by an
array of evidence...". The conclusions in the most recent 2007 IPCC Fourth Assessment
report have been significantly strengthened relative to what was originally concluded in
our work from the 1990s or in the IPCC 2001 Third Assessment Report, something that of
course should have been expected given the numerous additional studies that have since been
done that all point in the same direction. The conclusion that large-scale recent warmth
likely exceeds the range seen in past centuries has been extended from the past 1000 years
in the TAR, to the past 1300 years in the current report, and the confidence in this
conclusion has been upped from likely in the Third Assessment Report to very likely in the
current report for the past half millennium.
Since then, the conclusions have been further strengthened by other work, including work by
us. Please see e.g. the reporting by the BBC:
You don't seem to be aware of the fact that our original "Hockey Stick" reconstruction
didn't even use the "Yamal" data. It seems you have uncritically accepted nearly every
specious contrarian claim and innuendo against me, my colleagues, and the science of
climate change itself. Furthermore, I doubt that the various authors you cite as critics,
such as Pollack and Smerdon, would in any way agree w/ your assessment of this work.
Misrepresenting the work of scientists is a serious offense, and would work to further
besmirch the reputation of the Wall Street Journal, which is strongly been called into
question in the past with regard to the treatment of climate change.
I've copied my response to a number of others who might wish to comment further, as I will
be unavailable to speak with you until next week.
I've pasted below various summaries by mainstream news venues which reported a couple years
ago that the National Academy of Sciences, in the words of Nature "Affirmed The Hockey
Stick" below this message.
In addition, here are a few links you might want to read to better familiarize yourself
with what the science actually states with regard to the issues raised in your inquiry
Finally, let me suggest, under the assumption that your intent is indeed to report the
reality of our current scientific understanding, rather than contrarian
politically-motivated spin, that any legitimate journalistic inquiry into the current
state of the science, and the extent to which uncertainties and controversy have been
overstated and misrepresented in the public discourse, would probably choose to focus on
the issues raised here:
Mike Mann
___________________NEWS CLIPS ON ACADEMY REPORT_____________________
from BBC (6/23/06 "Backing for 'Hockey Stick' graph")
The Earth was hotter in the late 20th Century than it had been in the last 400 or possibly
1,000 years, a report requested by the US Congress concludes. It backs some of the key
findings of the original study that gave rise to the iconic "hockey stick" graph.)
from New York Times (Andy Revkin, 6/22/06 "Science Panel Packs Study on Warming Climate"):

At a news conference at the headquarters of the National Academies, several members of the
panel reviewing the study said they saw no sign that its authors had intentionally chosen
data sets or methods to get a desired result.

"I saw nothing that spoke to me of any manipulation," said one member, Peter Bloomfield, a
statistics professor at [17]North Carolina State University. He added that his impression
was the study was "an honest attempt to construct a data analysis procedure.

Boston Globe (Beth Daley, 6/22/06 "Report backs global warming claims"):

Our conclusion is that this recent period of warming is likely the warmest in a
(millennium), said John Wallace, one of the 12 members on the panel and professor of
atmospheric science at the University of Washington.
Los Angeles Times (Thomas H. Maugh II and Karen Kaplan, "U.S. Panel Backs Data on Global
After a comprehensive review of climate change data, the nation's preeminent scientific
body found that average temperatures on Earth had risen by about 1 degree over the last
century, a development that "is unprecedented for the last 400 years and potentially the
last several millennia."
The panel affirmed that proxy measurements made over the last 150 years correlated well
with actual measurements during that period, lending credence to the proxy data for earlier
It concluded that, "with a high level of confidence," global temperatures during the last
century were higher than at any time since 1600.
Although the report did not place numerical values on that confidence level, committee
member and statistician Peter Bloomfield of North Carolina State University said the panel
was about 95% sure of the conclusion.
The committee supported Mann's other conclusions, but said they were not as definitive. For
example, the report said the panel was "less confident" that the 20th century was the
warmest century since 1000, largely because of the scarcity of data from before 1600.
Bloomfield said the committee was about 67% confident of the validity of that finding the
same degree of confidence Mann and his colleagues had placed in their initial report.
Associated Press (syndicate with 100s of newspapers accross the U.S. (John Heilprin,
6/22/06 "The Earth is the hottest it has been in at least 400 years, perhaps even longer"):
The National Academy scientists concluded that the Mann-Bradley-Hughes research from the
late 1990s was "likely" to be true, said John "Mike" Wallace, an atmospheric sciences
professor at the University of Washington and a panel member. The conclusions from the '90s
research "are very close to being right" and are supported by even more recent data,
Wallace said.
Overall, the panel agreed that the warming in the last few decades of the 20th century was
unprecedented over the last 1,000 years, though relatively warm conditions persisted around
the year 1000, followed by a "Little Ice Age" from about 1500 to 1850.
Washington Post (Juliet Eilperin, 6/23/06 "Study Confirms Past Few Decades Warmest on
Panel member Kurt M. Cuffey, a geography professor at the University of California at
Berkeley, said at a news briefing that the report "essentially validated" the conclusions
Mann reported in 1998 and 1999 using temperature records. The panel also estimated there is
a roughly 67 percent chance that Mann is right in saying the past 25 years were the warmest
in a 1,000 years.
Nature (Geoff Brumfield, 6/28/06 "Academy affirms hockey-stick graph")
"We roughly agree with the substance of their findings," says Gerald North, the committee's
chair and a climate scientist at Texas A&M University in College Station. In particular, he
says, the committee has a "high level of confidence" that the second half of the twentieth
century was warmer than any other period in the past four centuries. But, he adds, claims
for the earlier period covered by the study, from AD 900 to 1600, are less certain. This
earlier period is particularly important because global-warming sceptics claim that the
current warming trend is a rebound from a 'little ice age' around 1600. Overall, the
committee thought the temperature reconstructions from that era had only a two-to-one
chance of being right.
says Peter Bloomfield, a statistician at North Carolina State University in Raleigh, who
was involved in the latest report. "This study was the first of its kind, and they had to
make choices at various stages about how the data were processed," he says, adding that he
"would not be embarrassed" to have been involved in the work.
New Scientist (Roxanne Khamsi, 6/23/06, "US report backs study on global warming"):
It was really the first analysis of its type, panel member Kurt Cuffey of the University of
California, Berkeley, US, said at a news conference on Thursday.

He added that it was the first time anyone has done such a large-scale and continual
analysis of temperature over time. So its not surprising that they could have probably done
some detailed aspects of it better.
But it was a remarkable contribution and gave birth to a debate thats ongoing, thats
teaching us a lot about how climate has changed.

Science (Richard Kerr, June 30, 2006, "Yes, Its been Getting Warmer in Here Since the CO2
Begain to Rise"):

In addition, none of the three committee members at the press briefing--North, Bloomfield,
and paleoclimatologist Kurt Cuffey of the University of California, Berkeley--had found any
hint of scientific impropriety. "I certainly did not see anything inappropriate," said
North. "Maybe things could have been done better, but after all, it was the first analysis
of its kind."

On Oct 23, 2009, at 10:41 AM, Jolis, Anne wrote:

Dear Dr. Mann,

My name is Anne Jolis, and I'm with the Wall Street Journal Europe, based in London. I'm
working on a piece about climate change, and specifically the growing questions that people
outside the field have about the methods and processes used by climatologists and other
climate-change scientists - and, necessarily, about the conclusions that result. The idea
came from the recent controversy that has arisen once again over Steve McIntyre, the
publication of the full Yamal data used in Keith Briffa's work. This of course raises
questions among climate scientistis, and observers, about whether the so-called "hockey
stick" graph of global temperatures , as produced by Dr. Briffa and originally by
yourself, was drawn from narrow data which, and then when broadened to include a wider
range of available dendroclimatological data, seems to show no important spike in global
temperatures in the last 100 year . I realize this is not exactly the silver-bullet to
anthropogenic global warming that some would like to read into it, but it seems to me that
it does underscore some of the issues in climate science. Specifically, the publication of
the data, and the earlier controversy over your work, seems to illustrate that best
practices and reliable methods of data collection remain far from established, and that
much of what is presented as scientific fact is really more of a value judgment based on
select data. Would you agree?

I'd love to get some insight from you for my article. I'll be filing this weekend, but I
can call you any time it's convenient for you on Friday - just let me know the best time
and number. Please note that if we do speak on the phone, I will email you with any quotes
or paraphrases that I would like to attribute to you, before publication, so as to secure
your approval and confirm the accuracy of what I'm attributing to you. Additionally, if
you'd like to correspond via email, that's fine too. I've listed below some of the
questions and assumptions I'm working on - if, in lieu of a phone call, you'd like to
answer and/or respond to these, as well as share any other thoughts you have on these
issues, I'd be most grateful. Feel welcome to reply at length!

I thank you in advance for your time and attention, and look forward to any of your

All the best,
Anne Jolis
Mobile: +44 799 079 3569

- Given that methods in climate science are still being refined, do you agree with policy
makers' and advocates' use of data such as your own? Do you feel it is accurately
represented to laymans, and that the inherent uncertainties present in the data are
appropriately underscored? As a citizen, do you feel there is enough certainty in the
conclusions of, for instance, the latest IPCC report, to introduce new economic
regulations? Why or why not?

-What methods do you feel are the most accurate for predicting future climate change, for
evaluatinag the causes of climate change and for predicting whether or what man can do to
try to control or mitigate climate change in the future in the future? Why do you feel
these methods are the most accurate? Do you feel they're given enough weight in the current

-What is your opinion of the value of Steve McIntyre's work? Clearly he is not a
professional scientist, but do you feel there is nonetheless a place for his "auditing" in
the climate science community? Why or why not?

-Do you think McIntyre's work and findings are likely to change the way leading climate
scientists operate? Do you think his recent campaign to get Dr. Keith Briffa to publish
the Yamal data he used is likely to make climate scientists more forthcoming with their
data? Do you think his work will make scientists, policymakers and advocates any more
exacting about the uncertainties in their procedures, methods and conclusions when they
present scientific data?

-How would you respond to the critique that, as a key part of the review processes of
publications in the field of climate science, as something of a "gatekeeper," you have
rejected and otherwise sought to suppress work that contradicted your work. Is this fair?
Why or why not? How would you characterize your selection process for work that is worthy
of publication?

-Do you stand by your original "hockey stick" graf, even after the publication of borehole
data from Henry Pollack and Jason Smerdon that seems to contradict your conclusions? Or
work published in 2005 by Hans von Storch that seems to indicate that the predictive
capabilities of the method you used in your original "hockey stick" would not be able to
predict current temperatures?

Michael E. Mann
Director, Earth System Science Center (ESSC)
Department of Meteorology Phone: (814) 863-4075
503 Walker Building FAX: (814) 865-3663
The Pennsylvania State University email: [18]mannatXYZxyz.edu
University Park, PA 16802-5013
website: [19]http://www.meteo.psu.edu/~mann/Mann/index.html
"Dire Predictions" book site:

Michael E. Mann
Director, Earth System Science Center (ESSC)
Department of Meteorology Phone: (814) 863-4075
503 Walker Building FAX: (814) 865-3663
The Pennsylvania State University email: [21]mannatXYZxyz.edu
University Park, PA 16802-5013
website: [22]http://www.meteo.psu.edu/~mann/Mann/index.html
"Dire Predictions" book site:

Michael E. Mann
Director, Earth System Science Center (ESSC)
Department of Meteorology Phone: (814) 863-4075
503 Walker Building FAX: (814) 865-3663
The Pennsylvania State University email: [24]mannatXYZxyz.edu
University Park, PA 16802-5013
website: [25]http://www.meteo.psu.edu/~mann/Mann/index.html
"Dire Predictions" book site:

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