Lawrence Solomon: 97% cooked stats
‘scientific consensus’ about global warming turns out to have
a lot more to do with manipulating the numbers
do we know there’s a scientific consensus on climate change? Pundits
and the press tell us so. And how do the pundits and the press know? Until
recently, they typically pointed to the number 2,500 — that’s
the number of scientists associated with the United Nations Intergovernmental
Panel on Climate Change. Those 2,500, the pundits and the press believed,
had endorsed the IPCC position.
their embarrassment, most of the pundits and press discovered they were
mistaken — those 2,500 scientists hadn’t endorsed the IPCC’s
had merely reviewed some part or other of the IPCC’s mammoth studies.
To add to their embarrassment, many of those reviewers from within the IPCC
establishment actually disagreed with the IPCC’s conclusions, sometimes
upshot? The punditry looked for and found an alternative number to tout:
“97% of the world’s climate scientists” accept the consensus,
articles in the Washington Post, the U.K.’s Guardian, CNN and other
news outlets now claim, along with some two million postings in the blogosphere.
This number will prove a new embarrassment to the pundits and press who
use it. The number stems from a 2008 master’s thesis by student Maggie
Kendall Zimmerman at the University of Illinois, under the guidance of Peter
Doran, an associate professor of Earth and environmental sciences. The two
researchers obtained their results by conducting a survey of 10,257 Earth
scientists. The survey results must have deeply disappointed the researchers
— in the end, they chose to highlight the views of a subgroup of just
77 scientists, 75 of whom thought humans contributed to climate change.
The ratio 75/77 produces the 97% figure that pundits now tout.
two researchers started by altogether excluding from their survey the thousands
of scientists most likely to think that the Sun, or planetary movements,
might have something to do with climate on Earth — out were the solar
scientists, space scientists, cosmologists, physicists, astronomers and
meteorologists. That left the 10,257 scientists in such disciplines as geology,
geography, oceanography, engineering, paleontology and geochemistry who
were somehow deemed more worthy of being included in the consensus. The
two researchers also decided scientific accomplishment should not be a factor
in who could answer — those surveyed were determined by their place
of employment (an academic or a governmental institution). Neither was academic
qualification a factor — about 1,000 of those surveyed did not have
a PhD, some didn’t even have a master’s diploma.
encourage a high participation among these remaining disciplines, the two
researchers decided on a quickie survey that would take less than two minutes
to complete, and would be done online, saving the respondents the hassle
of mailing a reply. Nevertheless, most didn’t consider the quickie
survey worthy of response — just 3,146, or 30.7%, answered the two
key questions on the survey:
When compared with pre-1800s levels, do you think that mean global temperatures
have generally risen, fallen, or remained relatively constant?
Do you think human activity is a significant contributing factor in
changing mean global temperatures?
questions posed to the Earth scientists were actually non-questions. From
my discussions with literally hundreds of skeptical scientists over the
past few years, I know of none who claims the planet hasn’t warmed
since the 1700s, and almost none who think humans haven’t contributed
in some way to the recent warming — quite apart from carbon dioxide
emissions, few would doubt that the creation of cities and the clearing
of forests for agricultural lands have affected the climate. When pressed
for a figure, global warming skeptics might say humans are responsible for
10% or 15% of the warming; some skeptics place the upper bound of man’s
contribution at 35%. The skeptics only deny that humans played a dominant
role in Earth’s warming.
Surprisingly, just 90% of the Earth scientists who responded to the first
question believed that temperatures had risen — I would have expected
a figure closer to 100%, since Earth was in the Little Ice Age in the centuries
immediately preceding 1800. But perhaps some of the responders interpreted
the question to include the past 1,000 years, when Earth was in the Medieval
Warm Period, generally thought to be warmer than today.
As for the second question, 82% of the Earth scientists replied that human
activity had significantly contributed to the warming. Here the vagueness
of the question comes into play. Since skeptics believe human activity has
been a contributing factor, their answer would have turned on whether they
consider a increase of 10% or 15% or 35% to be a significant contributing
factor. Some would, some wouldn’t.
In any case, the two researchers must have feared that an 82% figure would
fall short of a convincing consensus — almost one in five wasn’t
blaming humans for global warming — so they looked for a subset that
would yield a higher percentage. They found it — almost — by
excluding all the Earth scientists whose recently published peer-reviewed
research wasn’t mostly in the field of climate change. This subset
reduced the number of remaining scientists from over 3,000 to under 300.
But the percentage that now resulted still fell short of the researchers’
ideal, because the subset included such disciplines as meteorology, which
Doran considers ill-informed on the subject. “Most members of the
public think meteorologists know climate, but most of them actually study
very short-term phenomenon,” he explained, in justifying why he decided
to exclude them, among others. The researchers thus decided to tout responses
by those Earth scientists who not only published mainly on climate but also
identified themselves as climate scientists.
“They’re the ones who study and publish on climate science,”
Doran explained. “So I guess the take-home message is, the more you
know about the field of climate science, the more you’re likely to
believe in global warming and humankind’s contribution to it.”
Once all these cuts were made, 75 out of 77 scientists of unknown qualifications
were left endorsing the global warming orthodoxy. The two researchers, the
master’s student and her prof, were then satisfied with the
findings of her master’s thesis. Are you?
Lawrence Solomon is executive director of Energy Probe and author of The