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Thinking Scientifically About Climate
Science Communication
Dan M. Kahan
Yale University
& many others
Research Supported by:
National Science Foundation, SES-0922714, SES-06021840 & SES 02-42106
Evidence-based Climate Science Communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one
3. The solution
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
1.00
1.00
0.75
Greater 1.00
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.50
-0.75
-0.75
perceived risk (z-score)
0.50
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
Lesser -1.00
-1.00
low
high
high
high
U.S. general population
survey, N = 1,500.low
Scale 0 (“no risk at all”) to 10 (“extreme
risk”), M = 5.7,
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, 2, 732-35 (2012).
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
1.00
PIT prediction: Science Illiteracy & Bounded Rationality
1.00
0.75
Greater 1.00
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.50
-0.75
-0.75
perceived risk (z-score)
0.50
0.75
High Sci. litearcy/System 2 (“slow”)
0.50
0.25
0.00
-0.25
-0.50
-0.75
Low Sci. litearcy/System 1 (“fast”)
Lesser -1.00
-1.00
low
high
high
high
U.S. general population
survey, N = 1,500.low
Scale 0 (“no risk at all”) to 10 (“extreme
risk”), M = 5.7,
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, 2, 732-35 (2012).
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
1.00
1.00
Greater Risk
1.00
1.00
0.75
1.00
0.75
0.75
0.50
0.75
perceived risk (z-score)
0.75
0.50
0.50
0.50
PIT prediction
0.25
0.25
0.25
0.25
0.00
0.00
0.00
0.00
0.25
actual variance
-0.25
-0.25
-0.25
-0.25
-0.50
-0.50
PIT prediction
0.50
-0.50
actual variance
0.00
low vs. high sci
-0.25
low vs. high sc
-0.50
-0.50
-0.75
-0.75
-0.75
-0.75
-1.00
Lesser Risk-1.00
-1.00
30t
-0.75
low
30b
30t
high
point 1
point 2
Science literacy
30b
-1.00
30t
low
30b
point 1
-1.00
point 1
30b
high
30t
Numeracy
point 2
point 2
1
U.S. general population survey, N = 1,500. Scale 0 (“no risk at all”)point
to 10 (“extreme
risk”), M = 5.7,
SD = 3.4. CIs reflect 0.95 level of confidence.
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, 2, 732-35 (2012).
point 2
Evidence-based Climate Science Communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one
3. The solution
Evidence-based Climate Science Communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one: motivated reasoning
3. The solution
Cultural Cognition Worldviews
Hierarchy
hierarchical individualists
hierarchical communitarians
Individualism
Communitarianism
egalitarian individualists
egalitarian communitarians
Egalitarianism
Source: Kahan, D.M., Jenkins-Smith, H. & Braman, D. Cultural Cognition of Scientific Consensus.
J. Risk Res. 14, 147-74 (2011).
Cultural Cognition Worldviews
Risk Perception Key
Low Risk
High Risk
Hierarchy
Environment: climate, nuclear
hierarchical individualists
Guns/Gun Control
hierarchical communitarians
Individualism
Communitarianism
Environment: climate, nuclear
egalitarian individualists
Guns/Gun Control
egalitarian communitarians
Egalitarianism
Source: Kahan, D.M., Jenkins-Smith, H. & Braman, D. Cultural Cognition of Scientific Consensus.
J. Risk Res. 14, 147-74 (2011).
Climate Change
randomly assign 1
High Risk
(science conclusive)
Low Risk
(science inconclusive)
“It is now beyond reasonable scientific
dispute that human activity is causing
‘global warming’ and other dangerous
forms of climate change. Over the past
century, atmospheric concentration of carbon
dioxide (CO2)—called a “greenhouse gas”
because of its contribution to trapping heat—
has increased to historically unprecedented
levels. Scientific authorities at all major
universities agree that the source of this
increase is human industrial activity. They
agree too that higher C02 levels are
responsible for steady rises in air and ocean
temperatures over that period, particularly in
the last decade. This change is resulting in a
host of negative consequences: the melting of
polar ice caps and resulting increases in sea
levels and risks of catastrophic flooding;
intense and long-term droughts in many parts
of the world; and a rising incidence of
destructive cyclones and hurricanes in
others.”
“Judged by conventional scientific
standards, it is premature to conclude that
human
C02
emissions—so-called
‘greenhouse
gasses’—cause
global
warming. For example, global temperatures
have not risen since 1998, despite significant
increases in C02 during that period. In
addition, rather than shrinking everywhere,
glaciers are actually growing in some parts of
the world, and the amount of ice surrounding
Antarctica is at the highest level since
measurements began 30 years ago. . . .
Scientists who predict global warming
despite these facts are relying entirely on
computer models. Those models extrapolate
from observed atmospheric conditions
existing in the past. The idea that those same
models will accurately predict temperature in
a world with a very different conditions—
including one with substantially increased
CO2 in the atmosphere—is based on
unproven assumptions, not scientific
evidence. . . .”
Robert Linden
Position: Professor of Meteorology,
Massachusetts Institute of Technology
Education: Ph.D., Harvard University
Memberships:
 American Meteorological Society
 National Academy of Sciences
Robert Linden
Position: Professor of Meteorology,
Massachusetts Institute of Technology
Education: Ph.D., Harvard University
Memberships:
 American Meteorological Society
 National Academy of Sciences


American Association of Physics
National Academy of Sciences
Geologic Isolation of Nuclear Wastes
High Risk
(not safe)
“Using deep geologic isolation to dispose of
radioactive wastes from nuclear power
plants would put human health and the
environment at risk. The concept seems
simple: contain the wastes in underground
bedrock isolated from humans and the
biosphere. The problem in practice is that
there is no way to assure that the geologic
conditions relied upon to contain the wastes
won’t change over time. Nor is there any way
to assure the human materials used to
transport wastes to the site, or to contain
them inside of the isolation facilities, won’t
break down, releasing radioactivity into the
environment. . . . These are the sorts of
lessons one learns from the complex
problems that have plagued safety
engineering for the space shuttle, but here the
costs of failure are simply too high.
randomly assign 1
Low Risk
(safe)
“Radioactive wastes from nuclear power
plants can be disposed of without danger
to the public or the environment through
deep geologic isolation. In this method,
radioactive wastes are stored deep
underground in bedrock, and isolated from
the biosphere for many thousands of years.
Natural bedrock isolation has safely
contained the radioactive products generated
by spontaneous nuclear fission reactions in
Oklo, Africa, for some 2 billion years. Manmade geologic isolation facilities reinforce
this level of protection through the use of
sealed containers made of materials known to
resist corrosion and decay. This design
philosophy, known as ‘defense in depth,’
makes long-term disposal safe, effective, and
economically feasible.”
Oliver Roberts
Position: Professor of Nuclear Engineering,
University of California, Berkeley
Education: Ph.D., Princeton University
Memberships:
 American Association of Physics
 National Academy of Sciences
Oliver Roberts
Position: Professor of Nuclear Engineering,
University of California, Berkeley
Education: Ph.D., Princeton University
Memberships:
 American Association of Physics
 National Academy of Sciences
Concealed Carry Laws
High Risk
(Increase crime)
Low Risk
(Decrease Crime)
“So-called ‘concealed carry’ laws increase
violent crime. The claim that allowing
people to carry concealed handguns reduces
crime is not only contrary to common-sense,
but also unsupported by the evidence. . . .
Looking at data from 1977 to 2005, the 22
states that prohibited carrying handguns in
public went from having the highest rates of
rape and property offenses to having the
lowest rates of those crimes. . . .To put an
economic price tag on the issue, I estimate
that the cost of “concealed carry laws” is
around $500 million a year in the U.S.”
James Williams
Position: Professor of Criminology, Stanford
University
Education: Ph.D., Yale University
Memberships:
 American Society of Criminologists
 National Academy of Sciences
“Overall, ‘concealed carry’ laws decrease
violent crime. The reason is simple: potential
criminals are less likely to engage in violent
assaults or robberies if they think their
victims, or others in a position to give aid to
those persons, might be carrying
weapons. . . . Based on data from 1977 to
2005, I estimate that states without such laws,
as a group, would have avoided 1,570
murders; 4,177 rapes; and 60,000 aggravated
assaults per year if they had they made it
legal for law-abiding citizens to carry
concealed handguns. Economically speaking,
James Williams
the annual gain to the U.S. from allowing
Position: Professor of Criminology, Stanford
concealed handguns is at least $6.214
University
billion.”
Education: Ph.D., Yale University
Memberships:
 American Society of Criminologists
 National Academy of Sciences
Source: Kahan, D.M., Jenkins-Smith, H. & Braman, D. Cultural Cognition of Scientific Consensus.
J. Risk Res. 14, 147-74 (2011).
Featured scientist is a knowledgeable and credible expert on ...
Egalitarian Communitarian
More Likely to Agree
Hierarchical Individualist
More Likely to Agree
Pct. Point Difference in Likelihood of Selecting Response
-80%
60% 40%
-60%
-40%
20%
0
-20%
0%
20%
20%
40% 60%
40%
60%
80%
54%
Climate
Climate Change
Change
72%
Low Risk
High Risk
22%
Nuclear
Power
Nuclear Waste
31%
58%
Gun Control
n Control
61%
Low Risk
High Risk
ar Waste
Concealed
Carry
N = 1,500. Derived from ordered-logit regression analysis, controlling for demographic and political affiliation/ideology
variables. Culture variables set 1 SD from mean on culture scales. CIs reflect 0.95 level of confidence
Cultural Cognition Worldviews
Risk Perception Key
Low Risk
High Risk
Hierarchy
Environment: climate, nuclear
Guns/Gun Control
Gays military/gay parenting
hierarchical communitarians
Abortion procedure
compulsory psychiatric treatment
HPV Vaccination
Individualism
Communitarianism
Gays military/gay parenting
Environment: climate, nuclear
Abortion procedure
egalitarian individualists
compulsory psychiatric treatment
Egalitarianism
Guns/Gun Control
HPV Vaccination
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
1.00
Cultural variance conditional
Cultural Variance
on sci. literacy/numeracy?
1.00
0.75
1.00
1.00
1.00
Greater
Egalitarian Communitarian
0.75
0.50
0.50
0.50
0.25
0.25
0.25
0.25
perceived risk (z-score)
0.50
0.75
0.75 1.00 0.75
0.75
0.50
0.50
0.25
0.25
0.00
Low Sci lit/numeracy
0.00
0.00
0.00
0.00
0.00
High Sci lit/numeracy
-0.25
-0.25-0.25-0.25
-0.25
-0.25
-0.50
-0.50
-0.50
-0.50
-0.50
-0.75
-0.50
-0.75
-0.75
-0.75
-0.75
-0.75
-1.00
-1.00
-1.00
Lesser -1.00
Hierarchical Individualist
-1.00
low
low
low
low
high
high
high
high
high
high low
U.S.
general
population
survey,
N
=
1,500.
Scale
0
(“no
risk
at
all”)
to
10
(“extreme
risk”), M = 5.7,
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, advance online publication (2012),
doi:10.1038/nclimate1547.
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
PIT prediction: Culture as heuristic substitute
1.00
1.00
1.00
1.00
Greater
Egalitarian Communitarian
0.75
0.50
0.50
0.50
0.25
0.25
0.25
perceived risk (z-score)
0.75
0.75 1.00 0.75
0.75
0.50
0.50
0.25
0.25
Low Sci lit/numeracy
0.00
0.00
0.00
0.00
0.00
High Sci lit/numeracy
-0.25
-0.25-0.25-0.25
-0.25
-0.50
-0.50
-0.50
-0.50
-0.75
-0.75
-0.75
-0.75
-0.50
-0.75
-1.00
-1.00
-1.00
Lesser -1.00
-1.00
Hierarchical Individualist
low
low
low
low
high
high
high
high
low
high
U.S. general population survey, N = 1,500. Scale 0 (“no risk at all”) to 10 (“extreme risk”), M = 5.7,
SD = 3.4. CIs reflect 0.95 level of confidence.
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, advance online publication (2012),
doi:10.1038/nclimate1547.
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
Actual interaction of culture & sci-lit/num...
1.00
1.00
0.50
0.25
0.00
-0.25
-0.50
-0.75
Greater 1.00
1.00
1.00
0.75
1.00 0.75
0.75
0.75
0.50 0.75
0.50 0.50
0.50
0.50
0.25
0.25 0.25
0.25
0.25
0.00 0.00
0.00
0.00
0.00
-0.25
-0.25-0.25
-0.25
-0.25
-0.50
-0.50
-0.50 -0.50
-0.50
-0.75
-0.75
-0.75 -0.75
-0.75 -1.00
-1.00
-1.00
Lesser -1.00
perceived risk (z-score)
0.75
High Sci lit/numeracy
Egal Comm
Low Sci/lit numeracy
Egal Comm
Low Sci lit/numeracy
Low Sci lit/num.
Hierarc Individ
High Sci lit/numeracy
High Sci lit/numeracy
Hierarch Individ
low
high
low
high
low
high
high
low
high
high low
sci_num
U.S.
general
population
survey,
N
=
1,500.
Scale
0
(“no
risk
at
all”)
to
10
(“extreme
risk”), M = 5.7,
sci_num
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
-1.00
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, advance online publication (2012),
doi:10.1038/nclimate1547.
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
Actual interaction of culture & sci-lit/num...
1.00
1.00
0.50
0.25
0.00
-0.25
-0.50
-0.75
Greater 1.00
1.00
1.00
0.75
1.00 0.75
0.75
0.75
0.50 0.75
0.50 0.50
0.50
0.50
0.25
0.25 0.25
0.25
0.25
0.00 0.00
0.00
0.00
0.00
-0.25
-0.25-0.25
-0.25
-0.25
-0.50
-0.50
-0.50 -0.50
-0.50
-0.75
-0.75
-0.75 -0.75
-0.75 -1.00
-1.00
-1.00
Lesser -1.00
perceived risk (z-score)
0.75
High Sci lit/numeracy
Egal Comm
Low Sci/lit numeracy
Egal Comm
Low Sci lit/numeracy
Low Sci lit/num.
Hierarc Individ
High Sci lit/numeracy
High Sci lit/numeracy
Hierarch Individ
low
high
low
high
low
high
high
low
high
high low
sci_num
U.S.
general
population
survey,
N
=
1,500.
Scale
0
(“no
risk
at
all”)
to
10
(“extreme
risk”), M = 5.7,
sci_num
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
-1.00
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, advance online publication (2012),
doi:10.1038/nclimate1547.
“How much risk do you believe climate change poses to human health,
safety, or prosperity?”
1.00
POLARIZATION INCREASES as scil-lit/numeracy increases
1.00
0.50
0.25
0.00
-0.25
-0.50
-0.75
Greater 1.00
1.00
1.00
0.75
1.00 0.75
0.75
0.75
0.50 0.75
0.50 0.50
0.50
0.50
0.25
0.25 0.25
0.25
0.25
0.00 0.00
0.00
0.00
0.00
-0.25
-0.25-0.25
-0.25
-0.25
-0.50
-0.50
-0.50 -0.50
-0.50
-0.75
-0.75
-0.75 -0.75
-0.75 -1.00
-1.00
-1.00
Lesser -1.00
perceived risk (z-score)
0.75
High Sci lit/numeracy
Egal Comm
Low Sci/lit numeracy
Egal Comm
Low Sci lit/numeracy
Low Sci lit/num.
Hierarc Individ
High Sci lit/numeracy
High Sci lit/numeracy
Hierarch Individ
low
high
low
high
low
high
high
low
high
high low
sci_num
U.S.
general
population
survey,
N
=
1,500.
Scale
0
(“no
risk
at
all”)
to
10
(“extreme
risk”), M = 5.7,
sci_num
-1.00
SD = 3.4. CIs reflect 0.95 level of confidence.
-1.00
point 1
point 2
source: Kahan, D.M., Peters, E., Wittlin, M., Slovic, P., Ouellette, L.L., Braman, D. & Mandel, G. The polarizing impact of science
literacy and numeracy on perceived climate change risks. Nature Clim. Change, advance online publication (2012),
doi:10.1038/nclimate1547.
Evidence-based climate science communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one: motivated reasoning
3. The solution: evidence-based science communication
•
Methods: from lab models to field experiments
•
Location: locally (adaptation)
Lab models …
Cultural-credibility heuristic (HPV vaccine)
Risk Perception by Condition, Worldview
“The HPV vaccine is safe for use among young girls...”
3.5
Individualist
HierarchHierarchical
Individualist
80%
Egalitarian Communitarian
Egalitarian Communitarian
3.3
71%
70%
70%
2.8
2.5
2.3
Pct. Agree
3.0
66%
65%
61%
61%
60%
58%
56%
54%
50%
Kernel density estimate
Kernel density
estimate
Argument
without
Expected
Advocate
Kernel
density
estimate
No Argument
40%
10
Advocate
No Argument
8
Expected Advocate/Argument
Alignment
Expected
Argument/Advocate
Alignment
Balanced
Argument
8
No Argument
Unexpected
Intramural Advocate
Advocate Alignment
Alignment
Alignment
Argument
Unexpected Advocate/Argument
Alignment
Unexpected
Pluralistic Advocate/Argument
Alignment
Pluralistic
Argument
Argument/Advocate
Kernel density
estimate
Environment
Alignment
6
10
Density
8
10
8
10
47%
2.0
4
2
Density
0
4
2
Impact of narratives on high political sophistication hierarch individualists
(Monte Carlo simulation, m = 1,000)
.4
hhhihi
8
.6.7
hhhihi
.7
kernel = epanechnikov, bandwidth = 0.0099
kernel = epanechnikov, bandwidth = 0.0099
.7
Hperry/merck
guns
6
4
.8
.8
.9
big oil
lawyers
.8
.9
big oil
lawyers
kernel = epanechnikov, bandwidth = 0.0099
0
2
Density
.6
hhhihi
.9
Hperry/merck
guns
Hperry/merck
Hperry/merck big oil
big oil
.4
.5
.6
.7
kernel
= epanechnikov, bandwidth = 0.0099
guns
lawyers
guns
lawyers hhhihi
.5.6
0
10
.4.5
.5
Kernel density
estimate
.8
.9
2
0
0
.4
6
4
6
Density
4
6
2
Density
Narrative framing (campaign finance)
.4
.5
.6
.7
.8
.9
hhhihi
Likelihood of supporting campaign finance reform
Hperry/merck
guns
big oil
lawyers
kernel = epanechnikov, bandwidth = 0.0099
Identity-affirmation (climate change)
more
3.0
polarization
Diff. in study_validity
2.5
U.S.
2.0
US
1.5
UK
1.0
0.5
control
anti-pollution
geoengineering
less
0.0
polarization
England
control
control
anti-pollution
anti-pollution
geoengineering
geoengineering
Field experiments: Observe & measure
Evidence-based climate science communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one: motivated reasoning
3. The solution: evidence-based science communication
•
Methods: from lab models to field experiments
•
Location: locally (adaptation)
Local adaptation science communication
Evidence-based climate science communication
1. A plausible but incorrect explanation: the public irrationality thesis (PIT)
2. Another, better one: motivated reasoning
3. The solution: evidence-based science communication
•
Methods: from lab models to field experiments
•
Location: locally (adaptation)
Cultural Cognition Cat Scan Experiment
Go to www.culturalcognition.net!