My latest Mind and Matter column in the Wall
Street Journal is the third in the series on confirmation bias.
I argued last week that the way to combat confirmation bias-the
tendency to behave like a defense attorney rather than a judge when
assessing a theory in science-is to avoid monopoly. So long as
there are competing scientific centers, some will prick the bubbles
of theory reinforcement in which other scientists live.
For constructive critics, this is the problem with modern
climate science. They don't think it's a conspiracy theory, but a
monopoly that clings to one hypothesis (that carbon dioxide will
cause dangerous global warming) and brooks less and less dissent.
Again and again, climate skeptics are told they should respect the
consensus, an admonition wholly against the tradition of
Last month saw two media announcements of preliminary new papers
on climate. One, by a team led by physicist Richard Muller of the
University of California, Berkeley, concluded "the carbon dioxide curve gives a
better match than anything else we've tried" for the (modest) 0.8
Celsius-degree rise in global average temperatures over land during
the past half-century-less, if ocean is included. He may be right,
but such curve-fitting reasoning is an example of confirmation
bias. The other, by a team led by the meteorologist Anthony Watts,
a skeptical gadfly, confirmed its view that the Muller team's
numbers are too high-because "reported 1979-2008 U.S. temperature
trends are spuriously doubled" by bad thermometer siting and
Much published research on the impact of climate change consists
of confirmation bias by if-then modeling, but critics also see an
increasing confusion between model outputs and observations. For
example, in estimating how much warming is expected, the most
recent report of the Intergovernmental Panel on Climate Change uses
three methods, two based entirely on model simulations.
[Here is the actual wording: "Basing our
assessment on a combination of several independent lines of
evidence, as summarised in Box 10.2 Figures 1 and 2, including
observed climate change and the strength of known
feedbackssimulated in GCMs, we conclude that the global mean
equilibrium warming for doubling CO2, or 'equilibrium climate
sensitivity', is likely to lie in the range 2°C to 4.5°C, with a
most likely value of about 3°C."]
The late novelist Michael Crichton, in his prescient 2003
lecture criticizing climate research, said: "To an outsider, the most significant
innovation in the global-warming controversy is the overt reliance
that is being placed on models.... No longer are models judged by
how well they reproduce data from the real world-increasingly,
models provide the data. As if they were themselves a reality."
It isn't just models, but the interpretation of real data, too.
The rise and fall in both temperature and carbon dioxide, evident
in Antarctic ice cores, was at first thought to be evidence of
carbon dioxide driving climate change. Then it emerged that the
temperature had begun rising centuries earlier than carbon dioxide.
Rather than abandon the theory, scientists fell back on the notion
that the data jibed with the possibility that rising carbon dioxide
levels were reinforcing the warming trend in what's called a
positive feedback loop. Maybe-but there's still no empirical
evidence that this was a significant effect compared with a
continuation of whatever first caused the warming.
The reporting of climate in the media is full of confirmation
bias. Hot summers (in the U.S.) or wet ones (in the U.K.) are
invoked as support for climate alarmism, whereas cold winters are
dismissed as weather. Yale University's Dan Kahan and colleagues
polled 1,500 Americans and found that, as they learned more about
science, both believers and nonbelievers in dangerous climate
change "become more skillful in seeking out and making sense of-or
if necessary explaining away-empirical evidence relating to their
groups' positions on climate change and other issues."
As one practicing scientist wrote anonymously to a blog in 2009:
"honestly, if you know anything about my generation, we will do or
say whatever it is we think we're supposed to do or say. There is
no conspiracy, just a slightly cozy, unthinking myopia. Don't rock
Bring on the gadflies.