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MYTH #86: Oreskes consensus study was flawed


Naomi Oreskes claimed that every scientific paper endorsed manmade climate change — but she was wrong.


Virtually all the peer-reviewed climate research shows that climate change is a reality.

In 2004, Professor Naomi Oreskes surveyed more than 900 peer-reviewed papers on global climate change published between 1993 and 2003. She found that zero papers rejected the consensus view that manmade climate change is occurring. 75% of the papers agreed with the consensus and 25% made no comment either way. Anthropologist Benny Peiser criticized the Oreskes survey and initially claimed he found 34 papers that rejected the consensus view. But a close inspection of those 34 papers found his criticism invalid. Peiser himself has said: “I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact.” Simply put, the facts support Oreskes.

Additional info from Peter Norvig, Director of Research, Google

The consensus among climate researchers is outlined by the report of the Intergovernmental Panel on Climate Change

"Human activities … are modifying the concentration of atmospheric constituents … that absorb or scatter radiant energy. Most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations." 

This conclusion is endorsed by the U.S. National Academy of Sciences; the American Meteorological Society; the American Geophysical Union and its parent organization, the American Institute of Physics; the national science academies of the G8 nations, Brazil, China and India (PDF); and the American Association for the Advancement of Science

The consensus was quantified in a Science study by Prof. Naomi Oreskes in which she surveyed 928 scientific journal articles that matched the search "[global climate change]" at the ISI Web of Science. Of these, according to Oreskes, 75% agreed with the consensus view (either implicitly or explicitly), 25% took no stand one way or the other, and none rejected the consensus. 

Benny Peiser attempted to replicate the study, and found 34 articles that "reject or doubt" the consensus view — that is, 3% rather than the 0% that Oreskes found in her sample. Note that Peiser has altered Oreskes' original category from "reject" to "reject or doubt" so it is logically possible that both are correct. Also, there were several other differences between the studies: Peiser included "all documents" in the database rather than just scientific articles, and he included Social Sciences and Arts & Humanities as well as Sciences. Peiser was kind enough to share the 34 articles that he says reject or doubt. A discussion of the 34 argues that probably two to five of them should count, and the two best examples are editorials, not scientific publications (which is probably why they were not included in Oreskes' study). 

When faced with a controversy like this, the great thing is that you can do your own research. If you suspect Oreskes or Peiser (or both) might be biased, you can look at the data yourself. 

So that's what I did. Of the 34 articles, I would say that #10 and #27 clearly reject the consensus, but they are editorials, not scientific papers (and #27 is from an oil industry trade association). #1 and #6 doubt, but again are not scientific papers. #7, #17, #31 and maybe #22 doubt, and #15 says that both greenhouse gases and solar activity are roughly equal contributors to warming; so I counted it as "doubt." So overall I would say that Oreskes is correct; that Peiser has not shown a peer-reviewed scientific paper that clearly rejects the consensus. I would also say that Peiser is correct in that he found at least four papers that place some doubt on some of the premises of the consensus, but he is widely wrong in claiming 34. 

More recently, Peiser has backed off his claims, and now says there is actually only one out of the 34 papers that rejects the consensus, and that one is an editorial, not a scientific paper (and therefore was not included in the Oreskes study). 

Adapted from © Peter Norvig