The Myth of the Climate Change
'97%'
What is the origin of the false
belief—constantly repeated—that almost all scientists agree
about global warming?
By
Joseph Bast And Roy Spencer
The Wall Street Journal
May 26, 2014 7:13 p.m. ET
Last week Secretary of State John Kerry warned
graduating students at Boston College of the "crippling
consequences" of climate change. "Ninety-seven percent of the
world's scientists," he added, "tell us this is urgent."
Where did Mr. Kerry get the 97% figure? Perhaps from his boss,
President Obama, who tweeted on May 16 that "Ninety-seven percent of
scientists agree: #climate change is real, man-made and dangerous."
Or maybe from NASA, which posted (in more measured language) on its
website,
"Ninety-seven percent of climate scientists agree that
climate-warming trends over the past century are very likely due to
human activities."
Yet the assertion that 97% of scientists believe that climate change
is a man-made, urgent problem is a fiction. The so-called consensus
comes from a handful of surveys and abstract-counting exercises that
have been contradicted by more reliable research.
One frequently cited source for the consensus is a 2004 opinion essay published in
Science magazine by Naomi Oreskes, a science historian now at
Harvard. She claimed to have examined abstracts of 928 articles
published in scientific journals between 1993 and 2003, and found
that 75% supported the view that human activities are responsible
for most of the observed warming over the previous 50 years while
none directly dissented.
Ms. Oreskes's definition of consensus covered "man-made" but left
out "dangerous"—and scores of articles by prominent scientists such
as Richard Lindzen, John Christy, Sherwood Idso and Patrick
Michaels, who question the consensus, were excluded. The methodology
is also flawed. A study published earlier this year in Nature noted that
abstracts of academic papers often contain claims that aren't
substantiated in the papers.
Another widely cited source for the consensus view is a 2009 article in
"Eos, Transactions American Geophysical Union" by Maggie Kendall
Zimmerman, a student at the University of Illinois, and her master's
thesis adviser Peter Doran. It reported the results of a
two-question online survey of selected scientists. Mr. Doran and Ms.
Zimmerman claimed "97 percent of climate scientists agree" that
global temperatures have risen and that humans are a significant
contributing factor.
The survey's questions don't reveal much of interest. Most
scientists who are skeptical of catastrophic global warming
nevertheless would answer "yes" to both questions. The survey was
silent on whether the human impact is large enough to constitute a
problem. Nor did it include solar scientists, space scientists,
cosmologists, physicists, meteorologists or astronomers, who are the
scientists most likely to be aware of natural causes of climate
change.
The "97 percent" figure in the Zimmerman/Doran survey represents the
views of only 79 respondents who listed climate science as an area
of expertise and said they published more than half of their recent
peer-reviewed papers on climate change. Seventy-nine scientists—of
the 3,146 who responded to the survey—does not a consensus make.
In 2010, William R. Love Anderegg, then a student at Stanford
University, used Google Scholar to identify the views of the most
prolific writers on climate change. His findings were
published in Proceedings of the National Academies of Sciences. Mr.
Love Anderegg found that 97% to 98% of the 200 most prolific writers
on climate change believe "anthropogenic greenhouse gases have been
responsible for 'most' of the 'unequivocal' warming." There was no
mention of how dangerous this climate change might be; and, of
course, 200 researchers out of the thousands who have contributed to
the climate science debate is not evidence of consensus.
In 2013, John Cook, an Australia-based blogger, and some of his
friends reviewed abstracts of peer-reviewed papers published from
1991 to 2011. Mr. Cook reported that
97% of those who stated a position explicitly or implicitly suggest
that human activity is responsible for some warming. His findings
were published in Environmental Research Letters.
Mr. Cook's work was quickly debunked. In Science and Education in
August 2013, for example, David R. Legates (a professor of geography
at the University of Delaware and former director of its Center for
Climatic Research) and three coauthors reviewed the same papers as
did Mr. Cook and found "only 41 papers—0.3 percent of all 11,944
abstracts or 1.0 percent of the 4,014 expressing an opinion, and not
97.1 percent—had been found to endorse" the claim that human
activity is causing most of the current warming. Elsewhere, climate
scientists including Craig Idso, Nicola Scafetta, Nir J. Shaviv and
Nils- Axel Morner, whose research questions the alleged consensus,
protested that Mr. Cook ignored or misrepresented their work.
Rigorous international surveys conducted by German scientists Dennis
Bray and Hans von Storch—most recently published in Environmental Science &
Policy in 2010—have found that most climate
scientists disagree with the consensus on key issues such as the
reliability of climate data and computer models. They do not believe
that climate processes such as cloud formation and precipitation are
sufficiently understood to predict future climate change.
Surveys of meteorologists repeatedly find a majority oppose the
alleged consensus. Only 39.5% of 1,854 American Meteorological
Society members who responded to a survey in 2012
said man-made global warming is dangerous.
Finally, the U.N.'s Intergovernmental Panel on Climate Change—which
claims to speak for more than 2,500 scientists—is probably the most
frequently cited source for the consensus. Its latest report claims
that "human interference with the climate system is occurring, and
climate change poses risks for human and natural systems." Yet
relatively few have either written on or reviewed research having to
do with the key question: How much of the temperature increase and
other climate changes observed in the 20th century was caused by
man-made greenhouse-gas emissions? The IPCC lists only 41 authors
and editors of the relevant chapter of the Fifth Assessment Report
addressing "anthropogenic and natural radiative forcing."
Of the various petitions on global warming circulated for signatures
by scientists, the one by the Petition Project, a group of physicists
and physical chemists based in La Jolla, Calif., has by far the most
signatures—more than 31,000 (more than 9,000 with a Ph.D.). It was
most recently published in 2009, and most signers were added or
reaffirmed since 2007. The petition states that "there is no
convincing scientific evidence that human release of . . . carbon
dioxide, methane, or other greenhouse gases is causing or will, in
the foreseeable future, cause catastrophic heating of the Earth's
atmosphere and disruption of the Earth's climate."
We could go on, but the larger point is plain. There is no basis for
the claim that 97% of scientists believe that man-made climate
change is a dangerous problem.
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