The inability of climate assessment reports such as the CCSP Report “Temperature
Trends in the Lower Atmosphere: Steps for Understanding and Reconciling
Differences” to present the diversity of peer-reviewed scientific
perspectives on the subject should be a wake-up call to policymakers.
This lack of balance in the Reports is systemic in almost all such
assessments, including the IPCC Reports and the U.S. National Assessment.
If the goal of such reports is to provide a comprehensive perspective on
the state of climate science, then reports that enforce a limited
perspective, even if held by a majority of scientists, fail to accurately
present the state of science.
This problem in the assessment process is discussed in a recent EOS
article. In the November 27, 2005 issue of EOS, the news report “Meeting
Updates Progress of U.S. Climate Change Program” by Sarah Zielinski
Staff Writer has a quote by Antonio Busalacchi, Professor and Director of
the Earth System Science Interdisciplinary Center at the University of
” Busalacchi…called for the inclusion of a wider range of scientists,
including international scientists, in developing these reports. In
addition, he warned that some small scientific communities had become
‘incestuous’ with report authors reviewing their own work.”
In my Public Comment on the CCSP Report, I documented in detail how the climate
assessment committee I worked on sought to systematically exclude
scientific views that were not shared by the majority.
To move forward in the development of assessments of climate science which
includes the diversity of perspectives, the following framework might be
To serve on the Committee, members and the Chair, must be selected so as
to reflect the diversity of legitimate scientific perspectives. In cases
where the relevant expertise is only narrowly held, the committee should
strive for inclusion of relevant experts without a stake in the
assessment, and in some cases exclusion of those with a clear stake in the
As just one example, for the CCSP Report that I resigned from, one of the
major topics is the assessment of the recent multi-decadal surface
temperature trend record. There are several excellent scientists on the
Committee, but who have clear conflicts of interest on this fundamental
topic in the CCSP Report. This includes Tom Peterson, Chris Folland, David Parker, Tom Wigley, and myself, as well as the Chair, Tom Karl. Even the NRC Committee that was appointed to evaluate the first draft of the CCSP Report, had an individual with a conflict of interest in the outcome of the surface temperature trend assessment (Phil Jones). There are many well qualified scientists who could objectively assess the scientific issue of recent multi-decadal surface temperature trends, but who do not have the conflicts of interest.
But most importantly, the committee should be given a charge to review the
diversity of scientific perspectives and not to limit the discussion. When
I accepted serving on the Committee, I assumed that the individuals
with the conflict of interests would work together to assure that the
diversity of views on the science questions with respect to surface
temperature trends would be included. This was not the case.
The experience shows that no matter the scientific credentials of the Committee members, some individuals are so confident of their perspective that they exclude the views that do not conform to that view. Policymakers, as a result, obtain a Report that advocates a perspective rather than presents a balanced summary of the state of the science.