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SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCLIMATE2507

NATURE CLIMATE CHANGE | www.nature.com/natureclimatechange 11

Public division about climate change rooted in conflicting socio-political identities Key Measures: a) Demographic questions:

Is your country of residence the USA? o Yes o No

Are you:

o Male o Female

What year were you born? What is your postcode? Who lives with you in your current household? [Instruction: Tick all relevant categories]

o No one, I live by myself o I live with my partner o With one or more children o With one or both of my parents o With one or more adults who are neither my partner nor my parent

Please indicate whether any of the following full-time occupational categories applies to you at the present time. Are you engaged in____? [Instruction: Tick all the relevant full-time categories]

o Full-time paid employment o Full-time home or family care o Full-time retirement o Full-time volunteer o Full-time study o None of these

Please indicate whether any of the following part-time occupational categories applies to you. Are you in____? [Instruction: Tick the relevant part-time categories]

o Semi-retirement o Part-time paid employment o Casual employment o Part-time volunteer o Part-time study o Unemployed

Public division about climate change rooted in conflicting socio-political identities

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o None of these What level of education have you completed (or are currently completing):

o Tertiary (Postgraduate) o Tertiary (Bachelor Degree) o Tertiary (Diploma or Certificate) o Secondary (in full) o Secondary (partially completed) o Primary o No formal education

In terms of your annual personal or household income (whichever is most relevant to you), would you say it was:

o Well above the average American's income o Above average American's income o Around the same as the average American's income o Below the average American's income o Well below the average American's income

Introduction to the issue of climate change and self-categorization The opinion-based group membership was established in the following way. A brief introduction to the issue was provided followed by a self-categorization task. The self-categorization item was used as a filter question so that particular questions were answered separately by skeptics and believers. The paragraph used in the questionnaire was:

People’s views on climate change vary quite widely. For instance, some people are convinced that climate change is happening and is caused by human action (‘climate change believers’), while others have doubts about whether possible changes in the climate are caused by humans (‘climate change skeptics’). While your views might not fall exactly into one of these two categories, please indicate which category best represents your own views on climate change:

o Climate change believer o Climate change skeptic

Social identification measures Social identification with believers or with skeptics, and national social identification (social identification with Americans) were measured. Social identification as a believer or as a skeptic was measured for each group separately. The items were adapted from existing measures of social identification1 for each of the categories included. The full set of items was measured but we have only used the ten items measuring self-investment in each case. 1a. Believer social identification (filter used so only believers responded to these questions, answers scored on a scale from 1 strongly disagree to 7 strongly agree):


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(Group-level) Self-Investment: I feel a bond with other climate change believers. I feel solidarity with other climate change believers. I feel committed to other climate change believers. I am glad to be someone who is a climate change believer. I think that climate change believers have a lot to be proud of. It is good to be a climate change believer. Being a climate change believer gives me a good feeling. I often think about the fact that I am a climate change believer. The fact that I am a climate change believer is an important part of my identity. Being a climate change believer is an important part of how I see myself.

(Group-Level) Self-Definition: I have a lot in common with the average climate change believer. I am similar to the average climate change believer. Climate change believers have a lot in common with each other. Climate change believers are very similar to each other.

1b. Skeptic social identification (filter used so only skeptics responded to these questions, answers scored on a scale from 1 strongly disagree to 7 strongly agree): (Group-level) Self-Investment:

I feel a bond with other climate change skeptics. I feel solidarity with other climate change skeptics. I feel committed to other climate change skeptics. I am glad to be someone who is a climate change skeptic. I think that climate change skeptics have a lot to be proud of. It is good to be a climate change skeptic. Being a climate change skeptic gives me a good feeling. I often think about the fact that I am a climate change skeptic. The fact that I am a climate change skeptic is an important part of my identity. Being a climate change skeptic is an important part of how I see myself.

(Group-Level) Self-Definition: I have a lot in common with the average climate change skeptic. I am similar to the average climate change skeptic. Climate change skeptics have a lot in common with each other. Climate change skeptics are very similar to each other.

2. National social identification (questions given to the all sample, answers scored on a scale from 1 strongly disagree to 7 strongly agree): (Group-Level) Self-Investment:

I feel a bond with other Americans. I feel solidarity with Americans. I feel committed to America. I am glad to be American.


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I think that Americans have a lot to be proud of. It is pleasant to be American. Being American gives me a good feeling. I often think about the fact that I am American. The fact that I am American is an important part of my identity. Being American is an important part of how I see myself.

(Group-Level) Self-Definition: I have a lot in common with the average American. I am similar to the average American. Americans have a lot in common with each other. Americans are very similar to each other. In order to assess the validity of the measure we created an interaction term using the

product of the opinion-based group membership (coded 1 = skeptic and -1 = believer) and the self-investment aspect of social identification and correlated it with the segments of the 6 Americas tool (where alarmed was coded 1 and dismissive was coded 5 - the disengaged segment was empty). As expected there was a strong correlation, r = .774, between these measures so that high identifying skeptics were more likely to be dismissive or doubtful and high identifying believers were alarmed or concerned. This finding supports the validity of the measures. Note, however, that because the factors of group consciousness and measures of action need to be measured separately for the two causes (e.g., it does not make sense to ask believers whether they will support a skeptic protest rally) the subsequent analyses treat the groups separately. Collective action intentions (no filter used, answers scored on a scale from 1 strongly disagree to 7 strongly agree). Collective action intentions were measured using items previously employed in research on political engagement2. The items were adapted to reflect plausible behaviors to support their cause. The following items were used in the questionnaire:

Over the course of the next year, supporters of your position on climate change might call for people to take a number of actions on behalf of the cause. Please indicate how much you agree or disagree with the following statements about the actions you will take in support of your position on climate change. I will attend fund-raising events. I will donate money. I will go to a political rally. I will volunteer to help at a political event. I will assist political parties that support my position on climate change by contacting local voters. I will email a political leader I will participate in an on-line forum or social media discussion. I will call my local political representative's office.


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I will sign an on-line petition. I will help with delivering pamphlets to letterboxes. I will sign-up to receive information by email. I will talk to my friends about climate change issues. In the next election I will vote for a party with views on climate change that are aligned with mine.

Environmental behavior (no filter used, answers scored on a scale from 1 strongly disagree to 7 strongly agree). The items used to measure environmental behavior are based on items previously used in climate change research3:

I support measures to reward companies that reduce emissions. I support measures to punish companies that are not reducing emissions. I try to use less energy for heating in winter. I use public transport or car pool. I walk/bike instead of driving.

Group efficacy beliefs Group efficacy beliefs were measured for each group separately using items from collective action research4. The items were adapted to the context of climate change and a filter question was used (the self-categorization question placed at the beginning of the survey). 1. Group efficacy beliefs – Climate Change believers (answers scored on a scale from 1 strongly disagree to 7 strongly agree):

I feel that together climate change believers will be able to improve the situation in our country. I feel that climate change believers will be successful in our aims. I think that together climate change believers will be able to create positive change in the USA.

2. Group efficacy beliefs – Climate change skeptics (answers scored on a scale from 1 strongly disagree to 7 strongly agree):

I feel that together skeptics will be able to improve the situation in our country. I feel that skeptics will be successful in our aims. I think that together skeptics will be able to create positive change in USA.

Emotions about the future of the Earth’s climate (no filter used, answers scored on a scale from 1 not at all to 7 very much) This measure is based on items previously used in research on collective action in the context of the climate change crisis5.


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Thinking about the future of the Earth's climate I feel: o Hopeful o Optimistic o Despair o Fearful o Worried o Anxious o Afraid o Remorseful o Guilty

Emotions towards the opposing group Emotions towards the opposing group were measured separately for believers and skeptics using a filter question. The items are based on measures previously used in collective action research6. The measure of anger at the outgroup is a composite measure based on the average of scores for only three of the five items, that is, ‘outraged’, ‘angry’ and ‘fired-up’ because ‘amused’ (reversed scored) and ‘annoyed’ compromised the reliability of the scale. 1. Believers’ emotions towards skeptics (answers scored on a scale from 1 not at all to 7 very much)

Thinking about climate change skeptics I feel: o Outraged o Angry o Annoyed o Fired-up o Amused

2. Skeptics’ emotions towards believers (answers scored on a scale from 1 not at all to 7 very much)

Thinking about climate change believers I feel: o Outraged o Angry o Annoyed o Fired-up o Amused

Political party identification (answers scored on a scale from 1 not very strong Democrat to 6 strong Republican) The measures used to measure political party identification were the same as the ones used in the American National Election Study (ANES) survey (see http://www.electionstudies.org/):


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Generally speaking, do you think of yourself as a: o Republican o Democrat o Independent or Other

If Republican Is Selected

Would you call yourself: o a strong Republican o not very strong Republican

If Democrat Is Selected

Would you call yourself: o a strong Democrat o not very strong Democrat

If Independent or Other Is Selected

Do you think of yourself as: o closer to the Republican party o closer to the Democratic party

Moral foundations questionnaire Moral foundations were measured using the Moral Foundations Questionnaire using the 15 item scale7. The scores were calculated following the procedure detailed in the item key at http://www.moralfoundations.org/questionnaires. When you decide whether something is right or wrong, to what extent are the following considerations relevant to your thinking? (answers scored on a scale from 0 not at all relevant 5 extremely relevant) Part 1 – Moral Relevance

Harm: 1. Whether or not someone suffered emotionally 2. Whether or not someone cared for someone weak or vulnerable 3. Whether or not someone was cruel Fairness: 4. Whether or not some people were treated differently from others 5. Whether or not someone acted unfairly 6. Whether or not someone was denied his or her rights


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Ingroup: 7. Whether or not someone’s action showed love for his or her country 8. Whether or not someone did something to betray his or her group 9. Whether or not someone showed a lack of loyalty Authority: 10. Whether or not someone showed a lack of respect for authority 11. Whether or not someone conformed to the traditions of society 12. Whether or not an action caused chaos or disorder Purity: 13. Whether or not someone violated standards of purity and decency 14. Whether or not someone did something disgusting 15. Whether or not someone acted in a way that God would approve of

Part 2 – Moral Judgments Please read the following sentences and indicate your agreement or disagreement: (answers scored on a scale from 0 strongly disagree to 5 strongly agree)

Harm: 1. Compassion for those who are suffering is the most crucial virtue. 2. One of the worst things a person could do is hurt a defenseless animal. 3. It can never be right to kill a human being. Fairness: 4. When the government makes laws, the number one principle should be ensuring that everyone is treated fairly. 5. Justice is the most important requirement for a society. 6. I think it’s morally wrong that rich children inherit a lot of money while poor children inherit nothing. Ingroup: 7. I am proud of my country’s history. 8. People should be loyal to their family members, even when they have done something wrong. 9. It is more important to be a team player than to express oneself. Authority: 10. Respect for authority is something all children need to learn. 11. Men and women each have different roles to play in society. 12. If I were a soldier and disagreed with my commanding officer’s orders, I would obey anyway because that is my duty. Purity: 13. People should not do things that are disgusting, even if no one is harmed. 14. I would call some acts wrong on the grounds that they are unnatural. 15. Chastity is an important and valuable virtue.


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Actual behavior Actual behavior was measured for each group by giving participants the option to direct small donations to different organizations (the filter self-categorization question was used). This measure was developed from an existing measure of behavioral intentions8. 1. Climate Change believers

In addition to the payment you will receive for completing this survey we will donate $1 to another group for every participant in the study. You have the opportunity to decide how much of that $1 amount should be paid to groups campaigning on the climate issue or to a charity that is not involved in the climate debate (the American Society for the Prevention of Cruelty to Animals or ASPCA). You have the opportunity to recommend that the donated amount be paid entirely to one group in the climate debate, entirely to the ASPCA or to be split between the climate group and the ASPCA. Given the large number of participants in the study this has the potential to be a large donation. The group that will receive our donation is the Climate Reality Project a group headed by former Vice President Al Gore that looks to "put the heat on denial". Please select how much (in cents) of the $1 we should donate to the Climate Reality Project. Any remainder will be donated to the ASPCA.

o 0c o 10c o 20c o 30c o 40c o 50c o 60c o 70c o 80c o 90c o $1

2. Actual behavior – Climate Change skeptics

In addition to the payment you will receive for completing this survey we will donate $1 to another group for every participant in the study. You have the opportunity to decide how much of that $1 amount should be paid to groups campaigning on the climate issue or to a charity that is not involved in the climate debate (the American Society for the Prevention of Cruelty to Animals or ASPCA). You have the opportunity to recommend that the donated amount be paid entirely to one group in the climate debate, entirely to the ASPCA or to be split between the climate group and the ASPCA. Given the large number of participants in the study this has the potential to be a large donation. The group that will receive our donation is the Heartland Institute, a group that has been described as "the world’s most prominent think tank promoting skepticism about man-made climate change.” Please select how much (in


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cents) of the $1 we should donate to the Heartland Institute. Any remainder will be donated to the ASPCA.

o 0c o 10c o 20c o 30c o 40c o 50c o 60c o 70c o 80c o 90c o $1

Other instruments used in their original form include 6 Americas population segmentation tool9 and Identification with all humanity scale10 (see below). Six Americas tool – the 15-item screening instrument Recently you may have noticed that global warming has been getting some attention in the news. Global warming refers to the idea that the world’s average temperature has been increasing over the past 150 years, may be increasing more in the future, and that the world’s climate may change as a result. 1. What do you think? Do you think that global warming is happening? Yes...

o ...and I'm extremely sure o ...and I'm very sure o ...and I'm somewhat sure o ...but I'm not at all sure

No...

o ...and I'm extremely sure o ...and I'm very sure o ...and I'm somewhat sure o ...but I'm not at all sure

Or...

o I don't know 2. Assuming global warming is happening, do you think it is ...

o Caused mostly by human activities o Caused mostly by natural changes in the environment o Other


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o None of the above because global warming isn't happening 3. How worried are you about global warming?

o Very worried o Somewhat worried o Not very worried o Not at all worried

4. How much do you think global warming will harm you personally?

o Not at all o Only a little o A moderate amount o A great deal o Don't know

5. When do you think global warming will start to harm people in the United States?

o They are being harmed now o In 10 years o In 25 years o In 50 years o In 100 years o Never

6. How much do you think global warming will harm future generations of people?

o Not at all o Only a little o A moderate amount o A great deal o Don't know

7. How much had you thought about global warming before today?

o A lot o Some o A little o Not at all

8. How important is the issue of global warming to you personally?

o Not at all important o Not too important o Somewhat important o Very important o Extremely important


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9. How much do you agree or disagree with the following statement: "I could easily change my mind about global warming."

o Strongly agree o Somewhat agree o Somewhat disagree o Strongly disagree

10. How many of your friends share your views on global warming?

o None o A few o Some o Most o All

11. Which of the following statements comes closest to your view?

o Global warming isn't happening. o Humans can't reduce global warming, even if it is happening. o Humans could reduce global warming, but people aren't willing to change their

behavior so we're not going to. o Humans could reduce global warming, but it's unclear at this point whether we will do

what's needed. o Humans can reduce global warming, and we are going to do so successfully.

12. Do you think citizens themselves should be doing more or less to address global warming?

o Much less o Less o Currently doing the right amount o More o Much more

13. Over the past 12 months, how many times have you punished companies that are opposing steps to reduce global warming by NOT buying their products?

o Never o Once o A few times (2-3) o Several times (4-5) o Many times (6+) o Don't know

14. Do you think global warming should be a low, medium, high, or very high priority for the President and Congress?

o Low o Medium o High


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o Very high 15. People disagree whether the United States should reduce greenhouse gas emissions on its own, or make reductions only if other countries do too. Which of the following statements comes closest to your own point of view?

The United States should reduce its greenhouse gas emissions ... o Regardless of what other countries do o Only if other industrialized countries (such as England, Germany and Japan) reduce

their emissions o Only if other industrialized countries and developing countries (such as China, India

and Brazil) reduce their emissions o The US should not reduce its emissions o Don't know

Identification with all humanity scale As in the original form of the questionnaire the answers to this scale were scored from 1 to 5 for each of the three categories. How close do you feel to each of the following groups? (scored from 1 not at all close to 5 very close) a. People in my community b. Americans c. People all over the world How often do you use the word “we” to refer to the following groups of people? (scored from 1 almost never to 5 very often) a. People in my community b. Americans c. People all over the world How much would you say you have in common with the following groups? (scored from 1 almost nothing in common to 5 very much in common) a. People in my community b. Americans c. People all over the world Sometimes people think of those who are not a part of their immediate family as “family.” To what degree do you think of the following groups of people as “family?” (scored from 1 not at all to 5 very much) a. People in my community b. Americans c. All humans everywhere


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How much do you identify with (that is‚ feel a part of‚ feel love toward‚ have concern for) each of the following? (scored from 1 not at all to 5 very much) a. People in my community b. Americans c. All humans everywhere How much would you say you care (feel upset‚ want to help) when bad things happens to: (scored from 1 not at all to 5 very much) a. People in my community b. Americans c. People everywhere in the world How much do you want to be: (scored from 1 not at all to 5 very much) a. a responsible citizen of your community. b. a responsible American citizen. c. a responsible citizen of the world How much do you believe in (scored from 1not at all to 5 very much) a. being loyal to my community. b. being loyal to America. c. being loyal to all mankind. When they are in need‚ how much do you want to help (scored from 1 not at all to 5 very much) a. People in my community b. Americans c. People all over the world Fit indices for alternative models tested Given the varied and relatively weak relationships involving party identification we tested whether the variable had a direct effect on action independently of group consciousness (see Alternative model 1 in Supplementary Tables 1 and 2, Supplementary Figure 1, a). For both skeptics and believers the paths from party identification to action intentions and actual behavior were non-significant (-.02, -.03, and respectively .08, .01). We found no evidence to suggest improved fit when those paths were included. We also tested two additional models, that is, one model where both party identification and moral values were directly predicting socio-political action (with group consciousness not included in the model, see Alternative model 2 in Supplementary Tables 1 and 2, Supplementary Figure 1, b), and one model that only included group consciousness as a predictor (see Alternative model 3 in Supplementary Tables 1 and 2, Supplementary Figure 1, c). We found that for both skeptics and believers the paths from party identification to action were significant only for believers and only for action intentions (-.13, p <.05), with all the other paths non-significant (-.01, -.00, and -.07). For the skeptics group none of the three moral foundations included in the model predicted action (.21, .08, .08 for action intentions, and .08, .04, -.06 for actual behavior), while for


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believers, moral foundations did not significantly predict action (.11, .05 for action intentions, and .08, -.06 for actual behavior). Finally, in the Alternative model 3, for both skeptics and believers, the group consciousness factor significantly predicted action intentions (.69, .80), and actual behavior (.28, .30). In terms of the strength of relationships this model is almost identical to the model shown in Figures 1 and 2 of the paper (but less comprehensive). Fit statistics of these alternative models are presented in Supplementary Tables 1 and 2. a) Alternative model 1 b) Alternative model 2 c) Alternative model 3 Supplementary Figure 1. The alternative models predicting socio-political action. Supplementary Table 1. Comparative fit coefficients for alternative models for skeptics Figure 1

model Alternative model 1

Alternative model 2

Alternative model 3

AIC

64.955 86.155 56.164 33.581

CFI

1.00 1.00 .976 1.00

RMSEA .000

.000 .163 .000

λ2, p 16.955 (.859)

16.155 (.647)

4.164 (.041)

3.581 (.611)

Supplementary Table 2. Comparative fit coefficients for alternative models for believers Figure 2

model Alternative model 1

Alternative model 2

Alternative model 3

AIC

87.109 88.618 54.111 36.609

CFI

.973 .974 .931 .995

RMSEA

.054 .056 .215 .031

λ2, p

33.109 (.011)

30.618 (.010)

16.111 (.00)

6.609 (.251)

Political party identification

Actual behaviour

Action intentions

Moral foundations

identification

Group Consciousness

Political party identification

Action intentions

Action intentions

Actual behaviour

Actual behaviour


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Supplementary References: 1. Leach, C. W., et al. Group-level self-definition and self-investment: a hierarchical (multicomponent) model of in-group identification. Journ. Personal. Soc. Psychol. 95, 144 (2008). 2. Bliuc, A. M., et al. Opinion-based group membership as a predictor of commitment to political action. Eur. Journ.Soc. Psychol. 37, 19-32 (2007). 3. (Maibach et al (2011) 4. van Zomeren, M., Postmes, T., & Spears, R. Toward an integrative social identity model of collective action: a quantitative research synthesis of three socio-psychological perspectives. Psychol. Bull. 134, 504-535 (2008). 5. van Zomeren, M., Spears, R., & Leach, C. W. Experimental evidence for a dual pathway model analysis of coping with the climate crisis. J. Environ. Psych 30, 339-346 (2010). 6. van Zomeren, M., Leach, C. W., & Spears, R. Protesters as “Passionate Economists” A Dynamic Dual Pathway Model of Approach Coping With Collective Disadvantage. Personal. Soc. Psychol. Rev.16, 180-199 (2012). 7. Graham, J. et al. Mapping the moral domain. J. Personal. Soc. Psychol. 101, 366 -385 (2011). 8. Rabinovich, A., Morton, T. A., Postmes, T., & Verplanken, B. Collective self and individual choice: The effects of inter-group comparative context on environmental values and behaviour. British Journ. Soc. Psychol. 51, 551-569 (2012). 9. Leiserowitz, A. et al. Global Warming's Six Americas. Yale Project on Climate Change Communication (2011). 10. McFarland, S., Webb, M. & Brown, D. All humanity is my ingroup: A measure and studies of identification with all humanity. J. Personal. Soc. Psychol. 103, 830 (2012).


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SUPPLEMENTARY INFORMATION - images.nature.com€¦ · NATURE CLIMATE CHANGE ... o I live with my partner o With one or more children o With one or both of my parents o With one or