Current surveys may underestimate climate change skepticism evidence from list experiments in Germany and the USA

Strong public support is a prerequisite for ambitious and thus costly climate change mitigation policy, and strong public concern over climate change is a prerequisite for policy support. Why, then, do most public opinion surveys indicate rather high levels of concern and rather strong policy support, while de facto mitigation efforts in most countries remain far from ambitious? One possibility is that survey measures for public concern fail to fully reveal the true attitudes of citizens due to social desirability bias. In this paper, we implemented list-experiments in representative surveys in Germany and the United States (N = 3620 and 3640 respectively) to assess such potential bias. We find evidence that people systematically misreport, that is, understate their disbelief in human caused climate change. This misreporting is particularly strong amongst politically relevant subgroups. Individuals in the top 20% of the income distribution in the United States and supporters of conservative parties in Germany exhibit significantly higher climate change skepticism according to the list experiment, relative to conventional measures. While this does not definitively mean that climate skepticism is a widespread phenomenon in these countries, it does suggest that future research should reconsider how climate change concern is measured, and what subgroups of the population are more susceptible to misreporting and why. Our findings imply that public support for ambitious climate policy may be weaker than existing survey research suggests.

Reviewer #1: The concept of the manuscript is nice and very pertinent in the current scenario. Overall, the conceptualization of the idea is good, however, the write-up looks unstructured in places. The readability of the manuscript can be improved with a bit more work around the organization of the text and ideas.
Thank you.
Some of the specific remarks are as follows: 1. Introduction section: a. Please check the introduction section to identify sentences that appears incomplete. For example, the sentence on page 1, line 15 seems incomplete.
Thank you for noting this. We have gone through the entire manuscript to revise all such instances. Thank you for noting this. We have gone through the entire manuscript to revise all such instances.

Methods section:
a. Different approaches to measure skepticism are described well in detail which adds to the readability of the manuscript. I suggest including relevant sub-sections to add more structure to the text.
We have now divided this section in to five subsections to add more structure and clarity to the text.
b. In the methods section, while the approaches used to measure skepticism are described in detail, the section lacks any mention of the statistical analyses conducted, and covariates used. Highly recommend adding a paragraph describing analytical approaches. Though some of this is covered in the last paragraph of the methods section, it will be good to elaborate and cover these in little more detail.
We have revised this section by moving the more detailed methods discussion, previously located in the appendix, to the main text.
c. Three different approaches to estimate skepticism have been discussed which appear too heavy at times. Authors can consider taking out the approaches that have not been used to report the findings.
We agree that this can presentation can be dense at times. However, we believe it is important to include the three approaches presented in the main text as this allows interested readers to fully understand patterns of climate skepticism and is the norm in research using this method (e.g. Coppock 2017).
We have rewritten, and broken in to two sentences, to make clearer.

e. Page 8, line no. 170-174 -This looks like a limitation of the study. Suggest placing it under the discussion section.
We have moved this text to the discussion section. We have now added that we include these covariates in the Methods section.

b. It would be great if authors can provide a table describing the characteristics of respondents (such as age, sex, income, etc.) surveyed in both countries.
We have added full summaries of the characteristics of respondents across these dimensions in section 7 of the appendix.
c. The authors should try to organize the results section and discussion section carefully. Currently, the results section also has text which fits more under the discussion section. For example, Page 10 lines 205-206 seem more apt for the discussion section. Same for the paragraph on page 10, line 219 onwards. The deviations in findings and their explanation should be explored and discussed in-depth in the discussion section.
We have revised this section accordingly to more cleanly delineate between results and discussion. We have revised to include the full party titles here in text, to avoid confusion.

Conclusion : a. This section is well written and articulated. Overall recommendation is to identify the texts from the article that fits in the conclusion section.
We have revised accordingly, and added further discussion as to the generality of these findings.
Reviewer #2: General comments: I thank the author for this wonderful research, which is indeed informative and policy relevant. In the study, authors aim to assess the prevalence of climate skepticism while accounting for social desirability bias by using two methods. Further the study also identifies which particular sub-population are likely to hide climate skepticism. I foresee that the paper also has much to offer to the growing climate policy literature and offers insight on improving measurements of climate change concerns.

Thank you.
Overall the manuscript is well written and arguments flows logically. I have following minor comments: 1. In Line 15, I suppose the word against and rely need to be swapped.
We have revised this sentence, as it was previously unclear in its meaning.

In Line 18-23, author categorize sceptical beliefs into different components. This information is indeed interesting. However, are there any definitions of the term "climate skepticism". It would be also informative to define the term.
We have now added an explicit definition of skepticism to the introduction on lines 18 -20.

The 'Introduction' section seems to be heavily influenced by the results of the study. For instance, Line 52-57 mention the results of the study. Why is reporting of results required in the introduction section? I would suggest authors delete or rephrase these lines to refrain from duplication and over stating the hypothesis of the study.
We have removed this part of the text, and reincorporated such summaries in to the Results section.
4. Line 181-187 are difficult to understand because of the language. Kindly re-work on these lines so that the meaning is clearly communicated.
We have streamlined these sentences to more clearly communicate the implications for our study. Figure 2, author have discussed differences in climate skepticism for all the individual categories apart form gender (sex) in USA. From the Figure, I can notice that males in USA tend to be more skeptical than the females. This is an interesting finding and I would motivate the author to discuss the potential reasons for the same.

For
We have noted this effect identified on page 13. However, we do not engage in further discussion of this effect as it fails to pass the first placebo test, reducing our confidence in its validity.
Reviewer #3: This study attempts to assess the prevalence of climate skepticism while accounting for social desirability bias. The study has included both a list experiment and a direct question (the current approach) about trend and attribution belief in climate change in surveys administered in Germany and the USA. The study is interesting and has high potential to contribute to the existing literature not only climate skepticism but also on the method of list experiment.

Thank you!
Overall, introduction part is well organized and methodology is robust. Results are also nicely presented. However, they are not adequately discussed and compared to similar studies from other countries.
As there are no other studies measuring climate skepticism in this way, to our knowledge, we are unable to compare to studies in other countries. We have, however, added explicit calls for future research to engage in more cross-country comparison to gauge the generalisability of our findings.
In Conclusions, implications of findings are confined to Germany and USA context. In my opinion, findings also have implications beyond these two selected countries. It is important to present implications (in the end of current text of conclusions) in regional or global context.
We have added text to note how future research should examine the extent to which these results can also be identified in other countries and contexts.