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This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.

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Friday, April 29, 2016

Essentially All Climate Scientists Agree: Man-Made Global Warming is Real

Virtually Complete Unanimity of Acceptance of Man-Made Global Warming.  James Lawrence Powell recently published an article (Bulletin of Science, Technology & Society  1–4, 2016; DOI:10.1177/0270467616634958) which found that during 2013 and 2014 only 0.0058% of authors of peer-reviewed journal articles rejected the reality of man-made global warming.  Of the almost 70,000 authors of those articles only 4 reached that conclusion, giving a ratio of 1:17,352.  

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.
© 2016 Henry Auer

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