Supplementary Online Material
Table S1 Climate Change Threat Index Input Data (2002-2010)
Variable / Date Administered / Marginal Score / Sample Size / Variable / Date Administered / Marginal Score / Sample SizeQ12 / 3/1/2002 / 29 / 1006 / Q47A / 3/1/2006 / 13 / 1250
Q12 / 3/1/2003 / 28 / 1003 / Q47A / 6/1/2007 / 12 / 1250
Q12 / 3/1/2004 / 26 / 1005 / Q47A / 9/1/2007 / 9 / 1250
Q12 / 3/1/2006 / 36 / 1000 / Q53 / 6/1/2006 / 41 / 1501
Q12 / 3/1/2007 / 41 / 1009 / Q53 / 7/1/2006 / 43 / 2003
Q12 / 3/1/2008 / 37 / 1012 / Q53 / 1/1/2007 / 45 / 1708
Q12 / 3/1/2009 / 35 / 1012 / Q53 / 4/1/2007 / 47 / 2026
Q12 / 3/1/2010 / 28 / 1014 / Q53 / 4/1/2008 / 42 / 1000
Q13 / 9/1/2006 / 33 / 1001 / Q53 / 4/1/2009 / 47 / 2001
Q13 / 2/1/2007 / 41 / 1013 / Q53 / 5/1/2009 / 44 / 1000
Q13 / 9/1/2007 / 41 / 1011 / Q53 / 9/1/2009 / 35 / 1500
Q13 / 3/1/2008 / 39 / 1006 / Q53 / 4/1/2010 / 37 / 1002
Q2 / 6/1/2005 / 64 / 1000 / Q53 / 10/1/2010 / 32 / 2251
Q2 / 6/1/2007 / 70 / 1000 / Q58 / 4/1/2007 / 40 / 1002
Q2 / 6/1/2008 / 67 / 1000 / Q58 / 7/1/2008 / 38 / 1000
Q34 / 9/1/2003 / 59 / 675 / Q64 / 3/1/2002 / 64 / 1006
Q34 / 5/1/2006 / 66 / 1241 / Q64 / 3/1/2003 / 62 / 1003
Q34 / 8/1/2006 / 67 / 1206 / Q64 / 3/1/2004 / 58 / 1005
Q34 / 1/1/2007 / 70 / 1168 / Q64 / 3/1/2005 / 64 / 1004
Q35 / 4/1/2007 / 49 / 1052 / Q64 / 3/1/2006 / 66 / 1000
Q35 / 10/1/2007 / 52 / 1282 / Q64 / 3/1/2007 / 64 / 1009
Q35 / 12/1/2007 / 55 / 1133 / Q64 / 3/1/2008 / 62 / 1012
Q35 / 2/1/2009 / 43 / 864 / Q64 / 3/1/2009 / 57 / 1012
Q35 / 4/1/2010 / 38 / 881 / Q64 / 3/1/2010 / 49 / 1014
Q35 / 8/1/2010 / 38 / 847 / Q71 / 3/1/2002 / 53 / 1006
Q35 / 10/1/2010 / 43 / 1253 / Q71 / 3/1/2003 / 51 / 1003
Q38 / 3/1/2002 / 33 / 1006 / Q71 / 3/1/2004 / 51 / 1005
Q38 / 3/1/2006 / 35 / 1000 / Q71 / 3/1/2005 / 54 / 1004
Q38 / 3/1/2008 / 40 / 1012 / Q71 / 3/1/2006 / 58 / 1000
Q38 / 3/1/2009 / 38 / 1012 / Q71 / 3/1/2007 / 59 / 1009
Q38 / 3/1/2010 / 32 / 1014 / Q71 / 3/1/2007 / 60 / 1007
Q46 / 3/1/2006 / 50 / 1002 / Q71 / 3/1/2008 / 61 / 1012
Q46 / 4/1/2007 / 52 / 1002 / Q71 / 3/1/2009 / 53 / 1012
Q46 / 7/1/2008 / 46 / 1000 / Q71 / 3/1/2010 / 50 / 1014
Q46 / 6/1/2010 / 46 / 1000 / Q9 / 6/1/2002 / 43 / 3262
Q47 / 5/1/2006 / 53 / 1001 / Q9 / 6/1/2005 / 41 / 1000
Q47 / 8/1/2007 / 51 / 1200 / Q9 / 6/1/2006 / 48 / 1000
Table S-2 CCTI Iteration History
Iteration / Convergence / Criterion / Items / Reliability / AlphaF / AlphaB1 / 0.2451 / 0.001 / 14 / 0.700 / 0.624 / 0.518
2 / 0.0225 / 0.001 / 14 / 0.830 / 0.934 / 0.559
3 / 0.0065 / 0.001 / 14 / 0.839 / 0.944 / 0.569
4 / 0.0014 / 0.001 / 14 / 0.841 / 0.957 / 0.570
5 / 0.0004 / 0.001 / 14 / 0.842 / 0.958 / 0.571
Table S-3 Threat Index loadings and descriptive variable information
Variable Loading Order / Variable / Cases / Dimension 1 Loading / Mean / Std Deviation1 / Q12 / 8 / 0.94 / 32.50 / 5.07
2 / Q13 / 4 / 0.74 / 38.50 / 3.28
3 / Q2 / 3 / 0.96 / 67.00 / 2.45
4 / Q34 / 4 / 1.00 / 65.50 / 4.03
5 / Q35 / 6 / 0.95 / 44.07 / 5.59
6 / Q38 / 5 / 0.86 / 35.60 / 3.01
7 / Q46 / 4 / 0.97 / 48.50 / 2.60
8 / Q47 / 2 / -1.00 / 52.00 / 1.00
9 / Q47A / 3 / -0.96 / 11.33 / 1.70
10 / Q53 / 9 / 0.96 / 40.89 / 4.89
11 / Q58 / 2 / 1.00 / 39.00 / 1.00
12 / Q64 / 9 / 0.51 / 60.67 / 4.97
13 / Q71 / 9 / 0.98 / 54.50 / 3.79
14 / Q9 / 3 / 0.99 / 44.00 / 2.94
Dimension 1 Information
Eigen Estimate 1.6 of possible 1.97
Pct Variance Explained: 81.34
Weighted Average Metric: Mean: 44.99 St. Dev: 3.19
Data Measurement
1. Extreme Weather Events – Four measures of weather variability were compiled from the NOAA Climate Extremes Index (Gleason et. al. 2008) This data set is available online at: The four measures utilized were:
- Overall Climate Extremes Index – arithmetic average of six indicators of climatic extremes across the U.S. (CEI bdk-cei.01-12.results).
- Extremes in Maximum Temperature % of U.S. with maximum temperatures much above normal. (Step 1 dk-step1-hi.01-12.results).
- Extremes in 1 Day Precipitation Twice the value of the percentage of the U.S. experiencing extreme (more than 2 inches) one day precipitation events (dk-step4.01-12.results).
- Drought Levels - % of U.S. in severe drought based on the Palmer Drought Severity Index (dk-step3-lo.01-12.results).
2. Scientific Information: Measures were collected in three areas:
- Counts of articles on Climate Change in refereed journal Science - gathered from the Readers Guide to Periodicals (Readers Guide Full Text and Readers Guide Archive Search 4/30/2011 & 5/1/2011 on the following terms: "climate change" or "global warming" or greenhouse or "atmospheric carbon dioxide" in Smart Search)
- Counts of articles on Climate Change in fifteen popular scientific magazines (listed below)- gathered from the Readers Guide to Periodicals (Readers Guide Full Text and Readers Guide Archive Search 4/30/2011 & 5/1/2011 using the following terms: "climate change" or "global warming" or greenhouse or "atmospheric carbon dioxide" in Smart Search)
Aviation Week and Space TechnologyPopular Science
Current ScienceScience & Technology Review
DiscoveryScience News
Issues in Science and TechnologyScientific American
National GeographicSky and Telescope
Natural HistorySmithsonian
OmniTechnology Review
Physics Today
- Release of major climate change assessment reports -The release of major climate change assessment reports scored as a dummy variable (yes = 1) for the quarters in which a report was released. Information on the release of major climate reports was taken from Ekwurzell, Frumhoff, & McCarthy (2011). The following reports were included: 1) Arctic Climate Impact Assessment (2005), 2) IPCC Reports (varies years), 3) USGCRP 2009 Assessment and USGCRP 21 (2009), 4) the America’s Climate Choices report released by the NRC (2010).
3. Mass Media Coverage. We constructed a mass media index based on an additive index (alpha = .853) of three measures:
- Number of stories on climate change on the nightly news shows of the major broadcast TV networks (NBC, CBS, ABC) based on a Boolean keyword search of the Vanderbilt Television Archives using "global warming," "climate change," “greenhouse” and "sea level";
- Number of stories on climate change in the New York Times - The count of stories on climate change in the NY Times was collected by a Lexis-Nexis Academic Search 5/26/2010 using the following terms to search the NY Times complete text online using the following search string: (BODY(global warming) OR BODY(climate change) OR BODY(greenhouse effect) OR BODY(greenhouse gases) OR BODY(carbon dioxide w/4 issue) OR BODY(carbon dioxide w/4 problem) OR BODY(co2 w/4 problem) OR BODY(co2 w/4 issue) OR SUBJECT(global warming) OR SUBJECT(climate change)).
- Number of stories on climate change in the three major weekly magazine stories (Newsweek,Time, and U.S. News and World Report) - gathered from the Readers Guide to Periodicals (Readers Guide Full Text and Readers Guide Archive Search 4/30/2011 & 5/1/2011 on the following terms: "climate change" or "global warming" or greenhouse or "atmospheric carbon dioxide" in Smart Search.
4. Media Advocacy To capture media advocacy efforts, we utilized three measures:
- Number of stories on climate change in 12 major environmental magazines (listed below) - gathered from the Readers Guide to Periodicals (Readers Guide Full Text and Readers Guide Archive Search 4/30/2011 & 5/1/2011 on the following terms: "climate change" or "global warming" or greenhouse or "atmospheric carbon dioxide" in Smart Search.
American ForestsNational Wildlife
AudubonOceanus
E: The Environmental MagazineOrion
EnvironmentSierra
International WildlifeThe Bulletin of the Atomic Scientists
National ParksThe Mother Earth News
- Number of stories on climate change in 6 major conservative (listed below) - gathered from the Readers Guide to Periodicals (Readers Guide Full Text and Readers Guide Archive Search 4/30/2011 & 5/1/2011 on the following terms: "climate change" or "global warming" or greenhouse or "atmospheric carbon dioxide" in Smart Search.
Human EventsThe American Conservative
National ReviewThe American Spectator
ReasonWeekly Standard
- Number of New York Times mentions of “An Inconvenient Truth,” based on a Lexis-Nexis Academic Key Word search 6/7/2011
5. Elite Cues. To capture elite cues, we include three measures
- Congressional action statements on climate change issued by Republicans and Democrats identified by a keyword search of Lexis-Nexis Congressional (Sellers 2010: 79-80). Each statement was coded as either supporting, opposing, or neutral regarding Congressional legislative action to address climate change. One of the authors coded all of the statements, and a second coded 20% of the statements. The two codings were in 95% agreement regarding the nature of the Congressional statements.
- Number of Congressional hearings on climate change reported in the Proquest Congressional Data Base (5/6/2011) under "Global Climate Change," "Greenhouse Effect," “CO2” and "Carbon Dioxide."
- Senate and House roll call votes on climate change bills identified in the League of Conservation Voters National Environmental Scorecard (see Lindaman and Haider-Markel 2002: 97)
6. Control Variables - We added three control variables that have been hypothesized to influence public concern about the environment:
- Unemployment Rate - Bureau of Labor Statistics – series ID# - LNS1400000
- Gross Domestic Product – Bureau of Economic Analysis -
- War Deaths in Iraq and Afghanistan – Icasualty online archive of war casualties (
- Price of Oil – Energy Information Administration (
Table S4 – Descriptive Statistics of Data used in Analysis
Variables / Measures / Mean / Standard Deviation / Minimum / MaximumClimate Change Threat Index (CCTI) / 45 / 3.23 / 41.61 / 53.2
Extreme Weather Events / Overall Climate Extremes Index / 19.42 / 3.72 / 12.17 / 28.69
Extremes in Maximum Temperature / 0.13 / 0.07 / 0.03 / 0.35
Extremes in 1 Day Precipitation / 0.07 / 0.02 / 0.05 / 0.11
Drought Levels / 0.13 / 0.09 / 0.01 / 0.32
Scientific Information / Science Journal Articles on Climate Change / 25.42 / 8.76 / 11 / 47
Popular Scientific Magazine Articles on Climate Change / 19.81 / 7.88 / 8 / 36
Release of Major Scientific Report on Climate Change / 0.14 / 0.35 / 0 / 1
Mass Media Coverage / Media Index / 74.94 / 52.38 / 17 / 207
Media Advocacy / Environmental Magazine Articles on Climate Change / 21.86 / 11.54 / 6 / 47
Conservative Magazine Articles on Climate Change / 8.89 / 7.83 / 1 / 33
NY Times Mentions "An Inconvenient Truth" / 7.75 / 10.96 / 0 / 47
Elite Cues / Democrat Statements Favoring CC Action / 12.44 / 11.76 / 0 / 43
Republican Statements Opposing CC Action / 5.83 / 9.08 / 0 / 35
House Hearings on Climate Change / 5.39 / 6.84 / 0 / 21
Senate Hearings on Climate Change / 3.25 / 4.02 / 0 / 12
LCV Dem Pro-Env. Score / 83.56 / 5.69 / 75.5 / 94.05
LCV Rep Anti-Env. Score / 85.21 / 4.04 / 78.8 / 91
Control Variables / Unemployment Rate / 6.26 / 1.84 / 4.4 / 10
GDP (Constant 2005 $) / 12650.96 / 613.12 / 11477.9 / 13380.7
War Deaths in Iraq and Afghanistan / 161.53 / 90.57 / 0 / 362
Price of Oil / 54.31 / 24.49 / 17.7 / 117.55
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Table S5 Data Utilized in Analysis
Table S6 Survey Questions Utilized in Climate Change Perceived Threat Index (2002 - 2010)
Question / Dates Administered / Variable Name / SourceI'm going to read you a list of environmental problems. As I read each one, please tell me if you personally worry about this problem a great deal, a fair amount, only a little, or not at all. First, how much do you personally worry about...the 'greenhouse effect' or global warming? / March 2002, March 2003, March 2004, March 2006, March 2007, March 2008, March 2009, March 2010 / Q12 / Gallup Poll (AIPO)
Is the following something that you worry about a lot, is this something you worry about somewhat or is this something you do not worry about?...Global warming / September 2006, February 2007, September 2007, March 2008 / Q13 / Public Agenda Confidence in US Foreign Policy Index Poll
And in the next 10 years, how likely are you to be personally affected by the following threat?...Very likely, somewhat likely, not too likely, not at all likely...How likely are you to be personally affected by the effects of global warming? / June 2005, June 2007, June 2008 / Q2 / Transatlantic Trends Survey
Do you think global warming is an environmental problem that is causing a serious impact now, or do you think global warming isn't having a serious impact? / September 2003, May 2006, August 2006, January 2007 / Q34 / CBS News Poll
Do you think global warming is an environmental problem that is causing a serious impact now, or do you think the impact of global warming won't happen until sometime in the future, or do you think global warming won't have a serious impact at all? / April 2007, October 2007, December 2007, February 2009, April 2010, August 2010, October 2010 / Q35 / CBS News/New York Times Poll
Do you think that global warming will pose a threat to you or your way of life in your lifetime? / March 2002, March 2006, March 2008, March 2009, March 2010 / Q38 / Gallup/CNN/USA Today Poll
How important is the issue of global warming to you personally--extremely important, very important, somewhat important, not too important, or not at all important? / March 2006, April 2007, July 2008, June 2010 / Q46 / ABC News/Time/Stanford University Poll
How much do you personally worry about global warming--a great deal, a fair amount, only a little, or not at all? / May 2006, August 2007 / Q47 / Pew Global Attitudes Project Poll
If nothing is done to reduce global warming in the future, how serious of a problem do you think it will be for the United States--very serious, somewhat serious, not so serious or not serious at all? / March 2006, June 2007, September 2007 / Q47A / ABC News/Time/Stanford University Poll
Table S6 Survey Questions Utilized in Climate Change Perceived Threat Index (2002 - 2010) (cont.)
Question / Dates Administered / Variable Name / SourceIn your view, is global warming a very serious problem, somewhat serious, not too serious, or not a problem? / June 2006, July 2006, January 2007, April 2007, April 2008, April 2009, May 2009, September 2009, April 2010, October 2010 / Q53 / Pew News Interest Index/Believability Poll
Scientists use the term 'global warming' to refer to the idea that the world's average temperature may be about five degrees Fahrenheit higher in 75 years than it is now. Overall, would you say that global warming would be good, bad, or neither good nor bad? If Good, ask: Would you say it would be very good or somewhat good? If Bad, ask: Would you say it would be very bad or somewhat bad? If Neither, ask: Do you lean toward thinking it would be good, lean toward thinking it would be bad, or don't you lean either way? / April 2007, July 2008 / Q58 / ABC News/Washington Post/Stanford University Poll
Thinking about what is said in the news, in your view is the seriousness of global warming--generally exaggerated, generally correct, or is it generally underestimated? / March 2002, March 2003, March 2004, March 2005, March 2006, March 2007, March 2008, March 2009, March 2010 / Q64 / Gallup/CNN/USA Today Poll
Which of the following statements reflects your view of when the effects of global warming will begin to happen? They have already begun to happen. They will start happening within a few years. They will start happening within your lifetime. They will not happen within your lifetime, but they will affect future generations. They will never happen. / March 2002, March 2003, March 2004, March 2005, March 2006, March 2007, March 2007, March 2008, March 2009, March 2010 / Q71 / Gallup/CNN/USA Today Poll
I am going to read you a list of possible threats to the vital interests of the United States in the next 10 years. For each one, please tell me if you see this as a critical threat, an important but not critical threat, or not an important threat at all.... Global warming / June 2002, June 2005, June 2006 / Q9 / Gallup/CCFR Survey of American Public Opinion and U.S. Foreign Policy 1998
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