Subcommittee to Hold Global Warming HearingWitnesses to Testify on Climate Change Assessment Report
WASHINGTON – U.S. Rep. Ed Whitfield, R-Ky., chairman of the House
Energy and Commerce Subcommittee on Oversight and Investigations, has scheduled
a hearing for Wednesday, July 19 at 10 a.m. in room 2123 of the Rayburn
House Office Building entitled, “Questions Surrounding the ‘Hockey
Stick’ Temperature Studies: Implications for Climate Change Assessments.”
Dr. Edward Wegman will present his panel’s report but a full witness list
has not yet been finalized.
About the Wegman report:
‘It is important to note the isolation of the paleoclimate community;
even though they rely heavily on statistical methods they do not seem to be
interacting with the statistical community. Additionally, we judge that the
sharing of research materials, data and results was haphazardly and grudgingly
done. In this case we judge that there was too much reliance on peer review,
which was not necessarily independent. Moreover, the work has been
sufficiently politicized that this community can hardly reassess their public
positions without losing credibility. Overall, our committee believes that Dr.
Mann’s assessments that the decade of the 1990s was the hottest decade of
the millennium and that 1998 was the hottest year of the millennium cannot be
supported by his analysis.’
– Excerpt from Wegman report
Background: On June 23, 2005, following reports of a dispute
surrounding two key historical temperature studies prominently used in the U.N.’s
Intergovernmental Panel on Climate Change (IPCC) 2001 assessment report, the
Energy and Commerce Committee wrote the three authors of the studies, the IPCC,
and the National Science Foundation for information relating to the use of the
studies by IPCC.
The studies in question, by Dr. Michael Mann, et al, formed the basis for the
IPCC assessment’s conclusion that the increase in 20th century Northern
Hemisphere temperatures is “likely to have been the largest of any century
during the past 1,000 years” and that the “1990s was the warmest decade and
1998 the warmest year” of the millennium.
Questions about the reliability of the Mann studies were of interest because
they raised policy-relevant questions concerning the objectivity of the IPCC and
its reliance upon and “promotional” use of the studies’ ‘hockey stick’
shaped historical temperature reconstruction.
Following receipt of the letter responses, committee staff informally sought
advice from independent statisticians to determine how best to assess the
statistical information submitted. Dr. Edward Wegman, a prominent statistics
professor at George Mason University who is chair of the National Academy of
Sciences’ (NAS) Committee on Applied and Theoretical Statistics, agreed to
independently assess the data on a pro bono basis. Wegman is also a board member
of the American Statistical Association.
About the Wegman committee: Dr. Wegman assembled a committee of
statisticians, including Dr. David Scott of Rice University and Dr. Yasmin Said
of The Johns Hopkins University. Also contributing were Denise Reeves of MITRE
Corp. and John T. Rigsby of the Naval Surface Warfare Center. All worked
independent of the committee, pro bono, at the direction of Wegman. In the
course of Wegman’s work, he also discussed and presented to other
statisticians on aspects of his analysis, including the Board of the American
Statistical Association.
Among the panel’s findings and recommendations:
- Mann et al., misused certain statistical methods in their studies, which
inappropriately produce hockey stick shapes in the temperature history.
Wegman’s analysis concludes that Mann’s work cannot support claim that
the1990s were the warmest decade of the millennium.
Report: “Our committee believes that the assessments that the decade of
the 1990s was the hottest decade in a millennium and that 1998 was the hottest
year in a millennium cannot be supported by the MBH98/99 analysis. As
mentioned earlier in our background section, tree ring proxies are typically
calibrated to remove low frequency variations. The cycle of Medieval Warm
Period and Little Ice Age that was widely recognized in 1990 has disappeared
from the MBH98/99 analyses, thus making possible the hottest decade/hottest
year claim. However, the methodology of MBH98/99 suppresses this low frequency
information. The paucity of data in the more remote past makes the
hottest-in-a-millennium claims essentially unverifiable.”
- A social network analysis revealed that the small community of
paleoclimate researchers appear to review each other’s work, and reuse
many of the same data sets, which calls into question the independence of
peer-review and temperature reconstructions.
Report: “It is clear that many of the proxies are re-used in most of the
papers. It is not surprising that the papers would obtain similar results and
so cannot really claim to be independent verifications.”
- Although the researchers rely heavily on statistical methods, they do not
seem to be interacting with the statistical community.
Report: “As statisticians, we were struck by the isolation of communities
such as the paleoclimate community that rely heavily on statistical methods,
yet do not seem to be interacting with the mainstream statistical community.
The public policy implications of this debate are financially staggering and
yet apparently no independent statistical expertise was sought or used.”
- Authors of policy-related science assessments should not assess their own
work.
Report: “Especially when massive amounts of public monies and human lives
are at stake, academic work should have a more intense level of scrutiny and
review. It is especially the case that authors of policy-related documents
like the IPCC report, Climate Change 2001: The Scientific Basis, should not be
the same people as those that constructed the academic papers.”
- Policy-related climate science should have a more intense level of
scrutiny and review involving statisticians. Federal research should involve
interdisciplinary teams to avoid narrowly focused discipline research.
Report: “With clinical trials for drugs and devices to be approved for
human use by the FDA, review and consultation with statisticians is expected.
Indeed, it is standard practice to include statisticians in the
application-for-approval process. We judge this to be a good policy when
public health and also when substantial amounts of monies are involved, for
example, when there are major policy decisions to be made based on statistical
assessments. In such cases, evaluation by statisticians should be standard
practice. This evaluation phase should be a mandatory part of all grant
applications and funded accordingly.”
- Federal research should emphasize fundamental understanding of the
mechanisms of climate change, and should focus on interdisciplinary teams to
avoid narrowly focused discipline research.
Report: “While the paleoclimate reconstruction has gathered much
publicity because it reinforces a policy agenda, it does not provide insight
and understanding of the physical mechanisms of climate change… What is
needed is deeper understanding of the physical mechanisms of climate change.”
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