Powell writes “The
extent of the consensus among scientists on [man-made] global warming [(MGW)]
has the potential to influence public opinion and the attitude of political
leaders and thus matters greatly to society.
[The results developed here show] the consensus on [MGW] among
publishing scientists is above 99.99%, verging on unanimity.”
Powell screened peer-reviewed
articles found in the Web
of Science Core Collection database over 2013-2014, using the search terms
“global warming” or “global climate change” or “climate change”. He eliminated duplicate entries, and then
reviewed the titles and abstracts of the articles identified by the
search. He looked “for clear statements of
rejection [of MGW] or that some process other than [MGW] better explains the
observations.” Powell found only five journal
articles that fulfilled his criteria, two of which included the same
authors. Of the 69,406 individual
authors identified in the search, only 4 “rejected” MGW, giving the final
results stated above.
In peer review the
author(s) submit their manuscript to the journal editor. The editor selects (usually) three experts in
the specific field of the research who remain anonymous to the authors. The experts critically review the manuscript
and recommend acceptance or rejection, or quite commonly, raise questions
seeking clarifications from the authors.
This writer has found many published articles in which the authors
specifically thank the anonymous reviewers for their questions or suggestions,
stating that these have improved the thrust of the overall article. This process is the reason that Powell’s
search in only peer-reviewed journals enhances the impact of his final result.
Powell made note of
the earlier search by Cook and coworkers in 2013 that resulted in the
oft-quoted finding that among “abstracts expressing a position [emphasis
added by Powell] on [MGW], 97.1% endorsed the consensus position that humans
are causing global warming.” While this
itself is a high proportion of endorsements, it still leaves those who do not
accept the reality of MGW with the plausible (but misleading) argument that 3
in 100 scientists are not in agreement.
Powell explains
that the work of Cook and coworkers is fallible.
They segregated abstracts into seven categories of acceptance, and
sought positive assertions of acceptance in those categories. Articles having no such expressed acceptance were
excluded from the final enumeration, even though 7,930 of 11,944 articles
(66.4%) fell in this “no position” category.
Powell makes the valid criticism that scientists writing on a given facet
of the science of global warming, no matter how specialized, and having it pass
peer review, clearly accept the reality of MGW without having to state so
explicitly in the title or abstract. In
contrast, the procedure used by Cook and coworkers excluded such articles from
their tally. Thus the 97% acceptance
rate reported by Cook and coworkers is clearly an underestimate. Powell’s procedure improves on that of Cook
and coworkers, and provides an accurate assessment of the degree of acceptance
of MGW among practicing climate scientists.
Powell finds
that 99.99% of climate scientists
who actively publish in peer reviewed journals accept the reality of MGW,
“verging on unanimity”. He points out
that this finding is of great significance for policymakers and the general
public. Indeed, Powell points out that
the U. S. House of Representatives, a body consisting of 435 representatives,
has many-fold more members who reject the reality of global warming than is
found among publishing climate scientists.
He concludes “the peer-reviewed literature contains no convincing
evidence against [MGW].”
The Reality of
Man-Made Global Warming. There may be a number of reasons for someone
not to accept that MGW is occurring, but the objective result of climate
science is not among them. MGW is
already with us; it is growing more severe as man-made emissions of greenhouse
gases accumulate ever higher. Harmful
effects resulting from these activities will adversely affect life on earth for
generations. The reality of MGW demands
meaningful action by our policymakers to minimize its effects at the earliest
time possible.
