Chronicle of Higher Education
From the issue dated July 15, 2005
Demand for Their Data on Climate Chills Scientists
Congressman opens probe of researchers who have reported global warming
By RICHARD MONASTERSKY
In a move that many climate scientists find chilling, the chairman of
the U.S. House of Representatives Committee on Energy and Commerce is
investigating three professors whose work suggests that the earth is
warmer now than at any time in many centuries, and that greenhouse gases
from burning fossil fuels are largely to blame.
In highly unusual letters sent to the scientists late last month, Rep.
Joe Barton, a Texas Republican, demanded detailed documentation of the
hundreds of studies on which they have been authors or co-authors.
Mr. Barton also sent a letter to the director of the National Science
Foundation on the same day that requests information about the work of
the three professors, as well as a list of all grants and awards the
agency has made in the area of climate and paleoclimate science, which
in the past 10 years number 2,700.
Several climate scientists reached by The Chronicle expressed dismay at
the investigation and described it as harassment.
The investigation focuses on studies by Michael E. Mann, an assistant
professor of environmental science at the University of Virginia;
Raymond S. Bradley, a professor of geosciences at the University of
Massachusetts at Amherst; and Malcolm K. Hughes, a professor in the
University of Arizona's Laboratory of Tree-Ring Research.
Several independent studies have come to conclusions similar to theirs.
But the work of Mr. Mann and his colleagues has served as a lightning
rod for attacks by skeptics of greenhouse warming, in part because the
researchers' early studies, in 1998 and 1999, figured prominently in a
2001 report by the Intergovernmental Panel on Climate Change, a
U.N.-sponsored group known as the IPCC.
In the letters, Mr. Barton and Edward Whitfield, a Kentucky Republican
who heads the Subcommittee on Oversight and Investigations, say they
started the investigation because "this dispute surrounding your studies
bears directly on important questions about the federally funded work
upon which climate studies rely and the quality and transparency of
analyses used to support the IPCC assessment process."
They gave the scientists 18 days to assemble and send in the copious
data, some of which come from decades-old projects.
Mr. Barton's letters to the researchers and the National Science
Foundation drew criticism both from across the aisle and from scientists
in the field.
Rep. Henry A. Waxman, a California Democrat who is a member of Mr.
Barton's committee, issued a statement describing the requests as
"extraordinary demands" that are "burdensome and intrusive" in their
Mr. Waxman also questioned the motivation for the inquiries. He observed
that Mr. Barton had not held any hearings on global warming in his 11
years as chairman of the panel, and had "vociferously opposed all
legislative efforts in the committee to address global warming."
Mr. Waxman added, "These letters do not appear to be a serious attempt
to understand the science of global warming."
In response to Mr. Waxman's statement, Larry Neal, a spokesman for the
energy committee, said: "Mr. Waxman seems to understand a great deal
about political science, maybe even more than he knows about climate
science, and just possibly he's familiar with the methods of bullying
and harassment, too. What he doesn't appear to know is Chairman Barton's
telephone number, or he would have called to ask about the information
we're gathering. Given all that, maybe it's no wonder the congressman
would mistake an honest request for facts as something more sinister."
Mr. Mann, who is moving this month to become an associate professor at
Pennsylvania State University at University Park, said he would reply to
Mr. Barton's letter soon, but because of the legal issues involved, he
said, he could not comment in detail.
"I am pleased that the U.S. Congress has shown an interest in the issue
of climate change," he told The Chronicle. "I am confident that when
members of Congress take a look at the science, they will join with the
consensus of the world's scientists that the earth is indeed warming,
and that human activity has played a primary role in the warming
observed in recent decades."
But climate scientists in the United States and in Europe said they were
shocked by Mr. Barton's requests.
"It's a technical form of harassment by people in Congress who are
opposed to [the evidence of] global warming and basically want to
discredit the science so they don't have to worry about the policy
alternatives," said Thomas Crowley, a professor in the Nicholas School
of the Environment and Earth Sciences at Duke University.
Mr. Barton worked in the oil-and-gas industry before being elected to
Congress, in 1984. In the past decade, he has consistently ranked as one
of the top five recipients of campaign contributions from that industry,
according to the Center for Responsive Politics, a nonpartisan research
group that tracks money in politics.
Mr. Barton was unavailable for an interview. Kevin Schweers, a spokesman
for the committee, said he could not recall any similar previous request
by Mr. Barton to scientists.
Brawl Over the "Hockey Stick"
In their first study, published in the journal Nature in 1998, Mr. Mann
and his colleagues examined long-term records of tree rings, glacial-ice
layers, and coral-growth layers, all of which store information about
how the climate has changed, year by year, at specific places around the
globe. By mathematically combining records from various sites, the
researchers developed a temperature history of the Northern Hemisphere
dating back six centuries. Mr. Mann subsequently extended the analysis
to cover the past two millennia.
In graphical form, the data show temperatures going up and down over the
centuries by small amounts and then shooting upward in the 20th century
-- a shape that has been dubbed "the hockey stick."
In writing its 2001 report, the IPCC considered Mr. Mann's first two
studies and several separate analyses to draw the conclusion that it is
"likely that, in the Northern Hemisphere, the 1990s was the warmest
decade and 1998 the warmest year" in the past millennium.
Mr. Mann was one of 10 lead authors of the chapter in the report that
dealt with such data -- a connection that Mr. Barton wants to
investigate. He wrote a letter to the chairman of the U.N.'s
climate-change panel asking for a clarification of Mr. Mann's role in
drafting the report.
The professor's work drew the attention of Stephen McIntyre, an
independent researcher in Toronto who has worked in the mining industry.
Over the past several years, he has maintained a correspondence with Mr.
Mann and other climate researchers, requesting data and computer codes
in order to check their work.
Mr. McIntyre, working with Ross McKitrick, an associate professor of
economics at Canada's University of Guelph, has published two papers
accusing Mr. Mann and his co-authors of making errors in their analyses.
The computer algorithm used in their studies produces hockey-stick
patterns even where none are present in the original data, say the
Canadian researchers. They also say the papers by Mr. Mann's team rely
too heavily on records from old pine trees in select sites in western
North America. "If those are removed, then the hockey stick breaks
down," says Mr. McKitrick.
The two groups have waged a war over those issues on two blogs,
. In their
exchanges, Mr. Mann defends his work, saying that Mr. McIntyre and Mr.
McKitrick have made serious errors in their own analysis of his team's
Mr. Mann isn't the only one to have scrapped with the Canadian skeptics.
According to Mr. Crowley, the Duke professor, he received repeated
e-mail messages from Mr. McIntyre demanding data and documentation,
which grew increasingly threatening. "I'm usually happy to send people
some stuff," said Mr. Crowley, but "McIntyre comes back time and again.
He could take up a huge amount of time. It's like you have nothing
better to do in your life than answer questions from Stephen McIntyre."
Mr. McIntyre said he was not available for an interview. On his blog, he
says Mr. Mann has released data but not the computer code from his
studies. He also says his e-mail messages were not threatening.
According to David Stonner, of the Congressional-affairs office at the
National Science Foundation, Mr. McIntyre contacted the foundation last
year to ask for Mr. Mann's computer code. Mr. Stonner said the agency
had told Mr. McIntyre that the code was the intellectual property of Mr.
Mann, and that it was up to him to decide whether to release it.
Many scientists say the debate over Mr. Mann's early work is a side
issue, given the number of subsequent studies that have reached similar
findings using different data and methods. In February, Anders Moberg,
of Stockholm University, and his colleagues published a study in Nature
that combined tree-ring data with records taken from lake and ocean
Compared with Mr. Mann's analyses, Mr. Moberg's results had more
variation in temperature, especially during warm episodes in AD 1000 and
1100, and a cool spell in the late-16th century. But, the authors
conclude, "we find no evidence for any earlier periods in the last two
millennia with warmer conditions than the post-1990 period -- in
agreement with previous similar studies."
Despite such findings and similar reports, Mr. Barton's letters say that
other researchers have failed to replicate the findings of Mr. Mann and
his colleagues. That statement leads several researchers to conclude
that Mr. Barton's requests are intended for political purposes, not
scientific ones. Stefan Rahmstorf, professor of physics of the oceans at
Potsdam University, in Germany, said that "when you read these letters,
it becomes clear this is not a genuine interest in getting the best
scientific information, but rather this is an attempt to intimidate
James E. Hansen, director of NASA's Goddard Institute for Space Studies,
in New York City, said, "There is something rotten in Washington."
"These requests from Representative Barton," he said, "seem to be
harassment and a threat to researchers and agencies that deliver
scientific results that displease politicians."
Roger A. Pielke Jr., a professor of environmental studies at the
University of Colorado in Boulder, says the letters probably will not
In his scientific and popular articles, Mr. Pielke has established
himself as skeptical scientist who challenges dire predictions about
global warming. Nonetheless, he calls Mr. Barton's letters an "inane"
gesture that appears politically based, given their timing right before
the G-8 summit. If Mr. Barton "wants to get clarity for this dispute on
the hockey stick, then sending out these letters is unlikely to get
clarity." says Mr. Pielke.
Kevin E. Trenberth, head of the climate-analysis section at the National
Center for Atmospheric Research, said, "This is a bit frightening from
an individual scientist's standpoint. It could end up with scientists
having to spend a hell of a lot more time and overhead simply keeping
their records straight." He added that he had not kept all of his
computer code for past projects, especially because older codes might
not work on new computer platforms. "You ask 100 scientists whether they
can produce the code for something that was published seven years ago,"
he said, "and I would be surprised if you could find many that could
comply with it."
Hans von Storch, a professor of meteorology at the University of Hamburg
and director of the Institute for Coastal Research of the GKSS Research
Center, in Geesthacht, Germany, has published his own report criticizing
the studies done by Mr. Mann and his colleagues.
He said Mr. Mann made some mistakes in his analyses and did not explain
his methods well enough to allow other scientists to independently check
But Mr. von Storch distinguished between publishing a description of
methodology and releasing computer codes. "If I did get such a letter, I
would become desperate," he said. His colleagues often write the code
for his studies, he said, and "if I asked my colleagues whether they
still had the code, I'm not sure they would."
Even Mr. McKitrick, the critic of the global-warming studies at the
University of Guelph, says he could not comply with the kind of detailed
request that Mr. Barton sent to Mr. Mann and his colleagues. "If someone
in Ottawa asked me for all that," the Canadian economist says, "at the
very least I'd ask for a long extension."
EXCERPTS FROM LETTERS FROM JOE BARTON AND HENRY A. WAXMAN
To Michael E. Mann, an assistant professor of environmental sciences at
the University of Virginia, from Joe Barton (R.-Tex.), chairman of the
House of Representatives Energy and Commerce Committee, and Edward
Whitfield (R.-Ky.), chairman of the Subcommittee on Oversight and
" ... pursuant to Rules X and XI of the U.S. House of
Representatives, please provide the following information requested
below on or before July 11, 2005. ...
Provide the location of all data archives relating to each published
study for which you were an author or co-author and indicate: (a)
whether this information contains all the specific data you used and
calculations your sic performed, including such supporting documentation
as computer source code, validation information, and other ancillary
information, necessary for full evaluation and application of the data,
particularly for another party to replicate your research results; (b)
when this information was available to researchers; (c) where and when
you first identified the location of this information; (d) what
modifications, if any, you have made to this information since
publication of the respective study; and (e) if necessary information is
not fully available, provide a detailed narrative description of the
steps somebody must take to acquire the necessary information to
replicate your study results or assess the quality of the proxy data you
U.S. Rep. Henry Waxman to U.S. Rep. Joe Barton:
" ... These letters do not appear to be a serious attempt to
understand the science of global warming. Some might interpret them as a
transparent effort to bully and harass climate-change experts who have
reached conclusions with which you disagree. ... "