We conducted a three-wave online panel survey, two weeks before, during and four weeks after the UN climate conference 2015 (COP 21). The respondents were recruited via an online access panel of the external panel provider respondi, which is certified according to Global ISO 26362, a member of the European Society for Opinion and Market Research and of the German Society for Online Research (DGOF). The online access panel comprises 100,000 respondents in Germany, from which participants were randomly invited to participate in the survey. In a second step, the first-wave sample was quoted for age and sex, federal state and formal education to represent the distribution of these variables within the German population aged 18–69. The final sample comprised n = 1,121 participants who participated in all three surveys. Detailed descriptions of the time frame, number of respondents and sociodemographic data of each wave are presented in Supplementary Table 1.
Testing for educational bias.
Online access panels tend to suffer from educational bias31. To test for this, we compared our data to the micro-census data of the German Federal Bureau of Statistics for 2015 (see Supplementary Table 2). Small differences can be explained by the fact that our survey included people aged 18 and older while the micro-census data include adolescents from 15 years. Consequently, our data included fewer respondents without a school diploma and a slightly higher share in all other educational groups. Yet, particularly in the two most educated groups, we find almost no deviations from the official micro-census data. In the following, we will provide an overview of the measures used in the survey. The concrete wording of the survey questions is provided in the Supplementary Tables 2–12.
Taking note of news from COP 21.
In the second wave of the panel survey, which took place during the climate summit, we asked the respondents how frequently they had noticed news about COP 21 in five media sources (television news and informational programs, radio, printed newspapers and magazines, online newspapers and social networks) on a seven-point scale ranging from 0 (‘never’) to 6 (‘several times daily’).
Engagement with information about COP 21.
In addition to the passive reception of news about the climate conference, we were also interested in whether the respondents engaged actively with information about the COP 21—either in personal discussions with family, friends and colleagues, or online in the form of searching for further information or writing online comments. These four items were also measured using a seven-point scale from 0 (‘never’) to 6 (‘several times daily’).
The following measures were included in all three waves to map changes on six dimensions: climate change awareness, general knowledge about climate politics, event-related knowledge, efficacy of actions, attribution of responsibility, and behavioural intentions.
Climate change awareness.
The concept of climate change awareness is an established idea in social science that summarizes two kinds of attitudes towards climate change. It comprises a cognitive element (knowing and accepting that anthropogenic climate change exists), and an affective element (feeling that it constitutes a relevant problem)17, 24, 25, 32. Thus, our study contains two different measures for awareness: adhering to the scientific consensus; and personal relevance of climate change. Adherence to scientific consensus was measured using items that covered the main points of the Intergovernmental Panel on Climate Change consensus: the existence of a global warming trend, its anthropogenity, its potentially serious consequences—and the claim that scientific statements are true. The first three items were adapted from a study on climate scepticism among journalists33. Agreement with the scientific consensus was measured from 1 (‘strongly disagree’) to 5 (‘strongly agree). It was possible to decline to answer a question. For each wave, all four items were combined into a mean index (Cronbach’s α = 0.78). Personal relevance of climate change was assessed with one item in which respondents were asked to evaluate the personal importance of the issue on a five-point scale from 1 (‘not important at all’) to 5 (‘very important’).
We measure knowledge with regards to two dimensions that are both relevant for understanding the discussions around COP 21. One dimension concerns basic background knowledge, the other dimension concerns knowledge that is more closely related to the specific summit. Since current studies of climate-related knowledge do not cover knowledge regarding climate politics34, 35, 36, 37, the items were only partly based on extant literature. Two items (concerning the Kyoto Protocol and emissions trading) were modified from a study on political knowledge38, the other items were developed for the current study. We consider our knowledge test an explorative measure since we cover aspects of climate policy that have not yet been analysed in previous surveys. The questions were designed to vary in their level of difficulty and include event-specific information (such as the aim of the conference) as well as important background knowledge that is necessary to understand climate politics. The questions do not aspire to cover all relevant aspects of the field. The knowledge test was qualitatively pre-tested by a group of graduate students of journalism and validated by an independent expert from the Climate Service Center Germany of the Helmholtz-Zentrum Geesthacht. Each item provided four alternative answers plus the option to respond with ‘don’t know’. The items and answer options were rotated randomly. For the analysis presented in this paper, correct answers were coded as 1, while incorrect and ‘don’t know’ answers were coded as 0.
General knowledge about climate politics.
We measured people’s general factual knowledge using five multiple-choice items concerning the Kyoto Protocol, the development of CO2 emissions over the past two decades, emissions trading, mitigation, and different countries’ per capita CO2 emissions. These items are important, as citizens arguably should have a rough knowledge of different levels and trends of emitting CO2 in different countries to assess the respective roles assigned to, for example, emerging economies and Western industrialized countries. Also, people need to understand terms like mitigation or the Kyoto protocol to make sense of the debate around COP 21.
We measured the respondents’ factual knowledge closely related to the political event COP 21 with two multiple-choice items asking for the main goal of the summit and for the correct explication of the two-degree limit. The latter was one of the main issues during the Paris conference, and thus a recurring topic in media reporting on COP 21. The questions were posed in the same way as the general knowledge items.
Belief in efficacy of actions.
Confidence in personal and collective efficacy as well as belief in the efficacy of a global climate agreement were each measured with one item39, 40. Agreement was measured on a five-point scale ranging from 1 (‘strongly disagree’) to 5 (‘strongly agree’), including the option not to specify an answer.
Attribution of responsibility.
We assessed who the respondents saw as responsible for combating climate change using three items. Two items were newly developed; the item referring to Germany’s national responsibility was taken from a previous survey41. The items measured agreement with the responsibility of emerging countries, industrial nations and Germany to serve as a leading actor, again on a five-point scale with the option to refuse an answer.
People’s intentions to take personal responsibility in the form of future actions against climate change were measured for political actions and consumer choices: one item covered climate-friendly food choices, another item asked about climate-friendly transportation (similar items are used, for example, in the Eurobarometer42) and two items related to engaging politically in climate matters (through online petitions or engaging in environmental grassroots initiatives; both items have been tested in a previous study43). The five-point scale ranged from 1 (‘I would not like to do this in the future’) to 5 (‘I would like to do more of this in the future’). Both items regarding the willingness to participate in future political engagement were combined into a mean index (Cronbach’s α = 0.74). The other behavioural intentions were treated as single items.
The study was conducted in compliance with the Guidelines for Safeguarding Good Scientific Practice at Universität Hamburg. Informed consent was obtained from all respondents in the survey.
The full survey questionnaire and further information about the study is available at URL: www.climatematters.hamburg. The datasets generated during the current study are available to the scientific community from the corresponding author upon reasonable request.