Geoscience Reference
In-Depth Information
major scientific assessment.
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IPCC reports are subject to three distinct rounds of peer review, each
of which takes place over roughly two months. First, there is an initial round of expert review,
wherein several thousand scientists from all disciplines and with a wide range of backgrounds and
perspectives, drawn from academic, government, and nongovernmental organizations and industry,
are called upon to provide detailed comments on the content of the report. Lead authors are required
to consider and respond to all comments and make appropriate revisions, all of which are
documented and available online. The revision process is overseen by two independent review
editors with expertise in the specific subject areas of the chapter, to ensure that any legitimate issues
reviewers raise are dealt with in a satisfactory manner.
The revised draft report is then subject to the next round of review, the so-called government
review, which includes rereview by the original expert reviewers and additional review by
government representatives from all participating United Nations member nations. Each government
may choose how it implements its review. The U.S. government, for example, solicits public
comments through a notice in the
Federal Register
, in essence allowing anyone at all to serve as a
reviewer of the IPCC report.
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The revision process is again repeated. Finally, national governments
are again invited to comment on the report.
The final wording of the all-important summary for policy makers for each of the three working
groups is agreed upon word-by-word in a final plenary meeting in which government delegations are
present and can propose variant terms or make objections to specific wording, but the scientists are in
charge. The final version reflects a consensus on the precise wording of the report between the
scientists involved in the writing of the report and the representatives of the government delegations.
It is difficult to imagine a more open, inclusive, and responsible assessment process than that which
the IPCC follows.
The IPCC reports remain the gold standard for evaluating the state of scientific understanding of
climate change. They are intended to inform but, importantly, not prescribe policies for avoiding so-
prescriptions, as they should be, are left for policy makers and their constituents to decide.
These reports are consensus documents in every respect. They emphasize conclusions that are
based on results that have been replicated by independent studies, using differing approaches and
assumptions. They highlight where there is true uncertainty. They put greatest weight on findings that
are widely accepted by the scientific community, and downplay the more tentative findings of
individual articles departing from conventional wisdom that, as we have seen, frequently—but not
always—do not hold up when subject to further scrutiny by subsequent independent efforts.
Given the importance placed on the IPCC reports, there should be little surprise that a prime
tactic of climate change deniers has been to attempt to discredit the IPCC and its assessment process.
We saw such attacks in the assaults in 1995 on Ben Santer and the Second Assessment Report, and
they have escalated in more recent times.
Some of the attacks against the IPCC appeal to the belief that the organization is somehow
notion. In 2001, the NAS reviewed the findings of the IPCC at the request of Republican president
mostly due to human activities”—almost word-for-word the conclusion of the IPCC. The NAS
conclusions were in turn endorsed by the national academies of science of all of the major
