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Open Access

Peer-reviewed

Research Article

They reduce, we reduce: Perception of other countries’ climate effort predicts support for climate policies

Abstract

As public support influences policy choices, it is crucial to understand how people view climate policies. Based on the premise that individuals tend to be conditional cooperators, we derived the “They Reduce, We Reduce” hypothesis, according to which citizens’ support for climate policies in their own country is higher if they perceive a stronger climate effort by other countries. We tested this hypothesis with a survey study (N = 4,000) in China, India, Japan, and the United States. Findings show that participants who perceived that other countries were likely and willing to take action to reduce climate change, or that the major emitters in the world were currently making substantial efforts, were more supportive of implementing climate policies in their own country. We also observed interindividual variations in this effect, though the patterns differed between countries: The policy attitudes of individuals who felt personally obligated to combat climate change and those who supported their country’s unconditional efforts were less tied to such perceptions. These findings suggest that people respond to other countries’ actions, and policy attitudes should be understood in the context of global climate governance, with reciprocity playing an important role in mobilizing public support.

Citation: Tam K-P, Ohnuma S, Fairbrother M, Chan H-W (2025) They reduce, we reduce: Perception of other countries’ climate effort predicts support for climate policies. PLOS Clim 4(12): e0000755. https://doi.org/10.1371/journal.pclm.0000755

Editor: Francesco Lamperti, Institute of Economics (Scuola Superiore Sant'Anna / RFF-CMCC European Institute on Economics and the Environment, ITALY

Received: June 12, 2025; Accepted: October 29, 2025; Published: December 10, 2025

Copyright: © 2025 Tam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: The data file can be found in the supplementary materials.

Funding: The work described in this study was supported by grants awarded to Kim-Pong Tam from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. 16601122 to KPT); HKUST Institute for Emerging Market Studies with support from EY, Hong Kong, China (Project No. IEMS19HS02 to KPT); and the Fiscal 2019 Grant for Japan-Related Research Projects, The Sumitomo Foundation, Japan (Project No. SFJP20HS01 to KPT); and a grant awarded to Malcolm Fairbrother by the Swedish Research Council (Grant No. 2020-04725 to MF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

1. Introduction

The impacts of climate change are being felt in almost every corner of the world. Unfortunately, global emissions, the largest contributor behind climate change, are not declining. Total global emissions were higher in 2024 than they were in 2023 [1]. Also, global emissions have been increasing over the last half-century and have not yet reached the peak [2].

Emissions reduction is achievable when governments introduce ambitious and effective policies. For example, it is estimated that within the period from 2008 to 2016, the European Union Emissions Trading System alone saved 1.2 billion tons of carbon emissions, which amounted to 3.8% of total emissions in Europe during these years [3]. However, collectively speaking, the current efforts by all humanity are far from sufficient [4]. State and local governments all over the world must now deliver a quantum leap in implementation of ambitious emissions reduction policies.

Policy changes reflect public support—people’s approval of a policy and their willingness to bear the costs it implies [5]. For instance, public opposition is a key reason why carbon pricing schemes, though advocated by many economists and politicians, are usually not forceful enough, implemented but subsequently suspended, or even unimplemented at all [6]. A vivid illustration is the Yellow Vest Movement in France, which is thought to be partly fueled by the public’s concerns about the injustice and inequality implied in the carbon tax proposal [7,8]. Scientists and policymakers now face the challenge of understanding what drives public support for climate policies [9].

In this research, we argue that there is a need to situate the study of policy support in the global context by considering the influence of what other countries have done. Some scholars suggest that the core logic of global climate governance is reciprocity. That is, some states voluntarily initiate ambitious emissions reduction policies, with the anticipation that other counties will reciprocate by taking their own action [10,11]. With this in mind, we are interested in how citizens’ attitudes toward climate policies in their own country may respond to the perceived efforts of other countries. In the following, we first review previous findings regarding public support for climate policies in Section 1.1 and then introduce the concept of perceived efforts of other countries and explain the need for new research addressing this concept in Section 1.2. Next, we develop our hypotheses in Section 1.3. Following that, we describe the method of the study we conducted to test our hypotheses in Section 2, report our results in Section 3, and discuss the implications of our results and identify limitations and future directions in Section 4.

1.1. Public support for climate policies

Public attitudes influence public policymaking [12]. In the environmental domain, research has shown that the policy stringency of a country is positively associated with levels of public support [13]. Using longitudinal data spanning from 1983 to 2012 in six European countries, Bakaki et al. [14] observed that public opinion change predicted a country’s environmental policy output. Studies have also identified lack of broad public support as a major barrier to decarbonization [15,5].

According to recent reviews and meta-analyses (e.g., [16,17,9,18,6], support for climate policies follows from three types of factors. The first is policy attributes, which refers to the design features of a specific policy and the public’s perception of them. For example, individuals tend to prefer pull measures over push measures, policies perceived to be effective, and policies implying lower personal costs [17,18,19]. People also show strong concern over the procedural and distributional fairness of a policy [16,6]. The second group of factors is psychological orientations, which refers to such stable and dispositional orientations as ideology, values, worldviews and trust (e.g., [15,20]. Also relevant are climate change perceptions, including risk perception, attribution, and emotions (e.g., [21]). The third group is societal contexts, which refers to a host of factors characterizing society, economy, and institutions [9]. For example, people tend to show weaker support for climate policies when they perceive only minority support by others (e.g., [22]) and when the local economy is dependent on fossil fuels (e.g., [23]).

1.2. Research gap: Perceived climate efforts by other countries

Reciprocity between countries plays a role in global climate governance [10,11]. The Paris Agreement serves as a prime example. The agreement is not legally binding and lacks any top-down enforcement. Its effectiveness is grounded in the reciprocal efforts of all countries. It is anticipated that some leading states will voluntarily initiate ambitious emissions reduction policies, prompting other countries to ramp up their own actions in response. Indeed, policy research aimed at explaining international policy diffusion has demonstrated that the reciprocity mechanism may be at work. Findings suggest that the diffusion of climate policies across countries can be characterized as a relational or social influence process, wherein the policy choices of one government can encourage another government to adopt a policy innovation [24,25].

The reciprocity argument predominantly refers to the behavior of government leaders. It remains largely underexplored as to whether reciprocity also influences citizens’ support for climate policies. For this reason, we attempt to answer the following questions: (i) How do people perceive other countries’ efforts in mitigating climate change? (ii) To what extent is this perception associated with support for climate policies in their own country? (iii) Is the association moderated by personal moral obligation and support for unconditional national climate efforts?

We emphasize the need to examine perception of other countries’ climate efforts as studies have shown that perceptions about the problem of climate change—such as whether it is happening or not—and related issues—such as its impacts and other people’s beliefs about it—are significant for understanding individuals’ response to climate change. For instance, research has examined how perceptions of the impacts of climate change influence their support for policies and mitigation actions (e.g., [26,27]. Beliefs about other people’s awareness and beliefs regarding climate change, often referred to as second-order beliefs, also significantly shape climate action ([28]; [29]). However, to the best of our knowledge, no study has directly assessed how citizens perceive the climate efforts displayed by other countries, nor whether this perception is associated with support for policies in one’s own country.

We have identified some relevant studies that examined how the general public responds to hypothetical information regarding other countries’ climate action (e.g., [30]), but as we explain below, they cannot address our research questions.

Some studies suggest that many people are prepared to support domestic climate efforts even in the absence of similar efforts by other countries [31]. When asked explicitly whether their country “should do as much as it can to fight climate change, even if others do less” or “should do only as much as other countries do,” the majority of respondents from 26 countries preferred the former option [32]. In another study in the U.S., close to 80% of the respondents supported their country taking action regardless of what other countries do [33].

However, these findings do not necessarily mean that people are insensitive to the climate efforts of other countries. Even in the aforementioned studies, some respondents did think that their country should do only as much as other countries. More importantly, some experiments have found that, despite widespread support for emissions reductions, individuals’ support tend to decline if they are led to believe that other countries will not contribute [34,35]. A recent survey study found similar results [36]: respondents were more supportive of carbon taxation in their country under the hypothetical condition that the policy spread globally.

Another line of experiments examined people’s views toward their country’s participation in international climate agreements. They commonly examined the extent to which participants’ support depends on the various features of an agreement, such as the cost involved, stringency of enforcement, and, relevant to the present research, the number of other participating countries. Findings suggest that participants reported stronger support for their country’s commitment when agreement encompassed more countries (e.g., [37]). Bechtel et al. [38] estimated that when the number of participating countries increased from 20 to 160, support for commitment by one’s own country to the agreement increased by 15 percentage points (see also [39,40]).

Altogether, prior studies suggest that, to a certain degree, people are sensitive to what other countries are doing, or what they believe other countries are doing, when considering what effort they want their own country to make. However, this existing body of evidence still cannot adequately address our research questions for the following three reasons. First, these studies did not directly ask respondents to report their perception of the levels of efforts by other countries. They similarly provided participants with some hypothetical information embedded either in the options of a survey question (e.g., [32]; Uyduranoglu & Ozturk, 2021) or in an experimental manipulation (e.g., [37,34]). It was impossible to ascertain whether participants personally believed in the hypothetical information, and it was impossible to understand how participants actually perceived other countries’ efforts. As mentioned, individuals’ perceptions of matters related to climate change are crucial for understanding their responses to it (e.g., [27,41]). We consider it important to directly assess how individuals perceive the efforts displayed by other countries and examine its consequences.

Second, most of these previous studies did not actually measure participants’ attitudes toward climate policies. The outcome variable in these studies was either support for climate action as a general principle or support for the country’s commitment to an international agreement. These outcomes are important, but they cannot be conflated with attitudes toward domestic legal measures and policy devices that are aimed to address climate change [42].

Third, while these previous studies suggest that an average person, to some degree, is sensitive to the climate efforts by other countries are doing, most of them did not speak directly to the possibility of interindividual variations of such sensitivity.

In summary, we see the need for an original study that answers the three research questions we named. In a study we conducted, we directly measured participants’ perception of climate efforts by other countries and examined to what extent this perception predicted their support for climate change policies in their country. Additionally, we considered whether this association varies across individuals. In the following, we introduce our theoretical reasoning and hypotheses in detail.

1.3. Hypotheses

1.3.1. Effect of perception of climate effort by other countries.

Previous studies have not directly assessed people’s perceptions of other countries’ climate efforts. We thus set out to measure such perceptions. This measurement allows us to examine to what extent people’s views towards climate policies in their own country are associated with their perception of other countries’ efforts. Based on the notion of conditional cooperation in the study of social dilemma, we expect that this perception would be a potent determinant of support for climate policies.

Climate change presents a collective action problem [43,44,45]—a situation wherein individuals fail to work together to achieve some common good. As global warming reflects all countries’ emissions, they all have a role to play in addressing the problem. Reducing emissions will require that some prices be borne by individuals (e.g., cost and inconvenience incurred in lifestyle changes) and countries (e.g., reduced economic growth), but the benefits of their emissions reductions will be enjoyed by all individuals and countries. Consequently, they have an incentive to free ride. Failure to reduce emissions will eventually result in substantial damage to the global climate, entailing losses to humanity as a whole [46].

Collective action problems are challenging if participants focus only on their own interests. Nevertheless, studies have shown that cooperative behavior is not uncommon in social dilemmas [44]. One observation refers to the phenomenon of conditional cooperation [47,48]. Most individuals actually care about collective interests, but they are reluctant to cooperate simply because they fear that other people would defect and free ride. When they learn that others cooperate, they are willing to reciprocate and also cooperate [49]. Experimental studies have typically found that participants’ contribution to a public goods pool is a linear function of the contributions by other players (e.g., [50,51,52]). In other words, expectation of others’ cooperation tends to increase cooperative behavior. In the environmental domain, studies have shown that individuals are more ready to contribute to collective action (e.g., environmental activism, environmental policies) when they think that others also contribute [53,54] or when they generally trust other people’s benevolence and cooperativeness [55]. Extrapolating from these findings, it is reasonable to expect that when individuals perceive other countries to be effortful in the global climate agenda, they have less fear of free riders and therefore are more ready to act in the interest of the collective and support similar policy efforts in their country.

With the above reasoning, we propose the “They Reduce, We Reduce” hypothesis. We expect that perception of climate efforts by other countries is positively associated with support for climate policies. That is, individuals who perceive more climate efforts made by other countries report stronger support for the implementation of various climate policies in their own country (Hypothesis 1).

This hypothesis is also consistent with a key observation in social psychology: People tend to conform to behaviors that align with what others commonly do or approve of. According to the the Focus Theory of Normative Conduct [56], perceptions of what others prevalently think or do facing a similar situation (i.e., descriptive social norms) shape behavior by indicating which action is deemed to be adaptive and effective in a situation and suggesting the approval by others. In the environmental domain, individuals who perceive pro-environmental behavior to be normative are more likely to engage in such behavior (e.g., [57]). Perceiving a weak norm is also considered to be a barrier to environmental action [58]. Notably, interventions that highlight the prevalence of pro-environmental behavior are generally effective in bringing behavioral change [59]. These findings regarding the behavioral effects of social norms also hint that perceiving more climate efforts by other countries can potentially motivate people to support similar climate efforts in their country.

1.3.2. Interindividual variations.

Perception of climate efforts by other countries is unlikely to have a uniform effect on all individuals. Research suggests that there are substantial individual differences in cooperative behavior (e.g., [50]). Some individuals cooperate only when they expect similar efforts by others (i.e., conditional cooperators). Some individuals display general concern for the commons; they are ready to pay personal costs to benefit the common good, regardless of other people’s cooperativeness. These individuals are unconditional cooperators [60]. Based on this perspective, we hypothesize that individuals who perceive more climate efforts made by other countries report stronger support for various climate policies in their own country, but this association would be less pronounced among those who are unconditional cooperators (Hypothesis 2).

We operationalized the notion of unconditional cooperators in two ways. First, we considered moral obligation. Not everyone feels obligated to take action to address climate change. Some feel so, and they are intrinsically motivated to engage in mitigation actions [61]. Some do not, and they might locate the responsibility for mitigating climate change with others (e.g., other people, other countries) and are less interested in personally engaging in the issue of climate change [58]. We hypothesize that this individual difference in moral obligation would moderate the positive association between perception of other countries’ climate efforts and support for domestic efforts. Individuals who already feel morally obligated are expected to be unconditional cooperators. Their attitudes toward domestic climate policies are expected to be less contingent on the actions by other countries. That is, we expect that individuals who perceive more climate efforts made by other countries report stronger support for various climate policies in their own country, but this association would be less pronounced among those who already feel obligated for climate change mitigation (Hypothesis 2a).

The second operationalization of the notion of unconditional cooperators is based on a finding from previous studies. As reviewed, although most respondents, when asked explicitly, support the view that their own country’s efforts should be unconditional, regardless of other countries’ actions, some individuals held a contrary view, reporting that their country should only take action as long as other countries do so (e.g., [33]). Assuming that the direct question used in these studies is valid and not susceptible to response biases, we can conclude that some individuals explicitly identify with unconditional domestic efforts, while some others identify with conditional efforts. Accordingly, we hypothesize that this individual difference would moderate the positive association between perception of other countries’ climate efforts and support for domestic policies. For individuals who explicitly identify with conditional efforts by their own country, their attitudes toward domestic climate policies are expected to be contingent on their perception of other countries’ efforts. In contrast, this contingency would be weaker, or even absent, among individuals who identify with unconditional efforts by their own country (Hypothesis 2b).

2. Methods

2.1. Ethics statement

All procedures of the study were approved by the Human Research Ethics Committee of the Hong Kong University of Science and Technology (approval numbers: HPR #372 and HPR #413).

2.2. Study design

The data came from a survey study on human responses to climate change [62], with samples, representative in terms of the distribution of key demographics, from four countries: China, India, Japan, and the United States (see Table A in S1 Text for a comparison of these countries). These countries are among the world’s largest overall polluters (setting aside Russia, and the European Union taken as a whole), so establishing our hypothesized effects in these countries can generate relevant practical insights. Also, previous research has shown that psychological pathways to climate change attitudes and behaviors exhibit variations across societies (e.g., [63]). The literature on climate policy attitudes has focused heavily on the United States [15], so our inclusion of multiple countries allows us to test our hypotheses in both the Global North and Global South, which has been relatively underrepresented in the literature [64,65]. In our main analyses, we treated a range of demographic variables (age, gender, education, income) and climate change opinions (belief, worry, risk perception) as covariates. Recent reviews have suggested the relevance of these variables for understanding climate policy support (e.g., [16,18]). As our focus was to examine individuals’ perception of other countries efforts and its potential association with policy support, we deem a cross-sectional study with the use of survey data suitable. However, it is necessary to be cautious that this study design does not allow any inference of causality.

2.3. Participants

In total, 4,000 participants (1,000 from each country) were recruited. The participants were sampled with the service by Ipsos. The samples were nationally representative in terms of distributions of gender and age. Participants from diverse income levels and education levels were included (see Table B in S1 Text for the distributions of demographic factors).

All participants were presented with a consent form on the very first page of the online survey. They could proceed to complete the study only after clicking “Yes” on that page to indicate that they fully understood the content of the form and agreed to participate in the study. All participants in the sample passed two instructional manipulation checks embedded in the survey (wherein they were instructed to choose a specific answer to the question); Ipsos removed participants who failed the checks and replaced them until the target sample size was attained.

The survey was launched on 16 July 2021, and data collection was completed on 3 August 2021.

2.4. Measures

2.4.1. Policy support.

Participants reported their levels of support regarding 14 emissions reduction and climate policies using a 7-point scale (1 = completely against to 7 = completely in favour). There was an option of “Don’t know,” which was treated as a missing value. This measure displayed configural invariance (but not metric or scalar invariance) across the four countries (see Box A in S1 Text for details). For each participant, we computed the mean score across all items. This measure showed strong internal reliability (α = .93, .89, .87, and .91 in the U.S., India, China, and Japan, respectively) (see Table 1 for descriptive statistics; readers interested in descriptive statistics regarding each specific policy may refer to Table C in S1 Text). (SUPPORT)

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Table 1. Descriptive statistics of policy support and perceived climate efforts by other countries.

https://doi.org/10.1371/journal.pclm.0000755.t001

2.4.2. Perception of climate efforts by other countries.

We included three measures. We used multiple measures as this was a pioneering study on this concept and there was no established measure. The items, with different wordings, referred to a general outlook of the efforts and commitments by countries in the world (see Table 1 for descriptive statistics). All items were phrased in a general manner, referring to climate actions broadly, without specifying the actions or policies taken by other countries. The reason was that we were unsure how informed our prospective participants would be about specific climate actions, as studies have shown that most individuals do not fully understand even basic climate-related terms frequently used by experts—such as carbon neutrality, mitigation, or adaptation [66].

  • Participants responded to “How likely do you think it is that governments in enough countries will take action to significantly reduce climate change?” on a 5-point scale (1 = not at all likely to 5 = extremely likely). There was an option of “Don’t know,” which was treated as a missing value. (LIKELY)
  • Participants indicated their agreement with this statement “I believe that governments of most countries in the world are willing to take action to reduce climate change” with a 5-point scale (1 = strongly disagree to 5 = strongly agree). (WILLING)
  • Participated rated how much effort each of the following countries or regions was currently making to reduce climate change on a 5-point scale (1 = no effort at all to 5 = a great deal of effort): China, the U.S., India, Russia, Japan, and the European Union. We only included this subset of countries/regions to avoid overburdening our participants; also, these countries represent the top emitters in the world and are arguably most responsible for reducing climate change. For each participant, we took the average of their ratings with respect to the five countries/regions excluding their own. This measure was reliable (α = .85, .80, .80, and .75 in the U.S., India, China, and Japan, respectively). There was an option of “Don’t know”; choosing this option was treated as a missing value. (EFFORT)

2.4.3. Moral obligation.

We measured this construct with three items: “I am responsible for the happening of climate change,” “I feel a personal responsibility to try to reduce climate change,” and “Thinking about my contribution to climate change, I feel guilty.” Participants responded on a 5-point scale (1 = strongly disagree to 5 = strongly agree). This measure was reliable (α = .83, .65, .75, and .90 in the U.S., India, China, and Japan, respectively). (OBLIGATION; see Table 1 for descriptive statistics)

2.4.4. Support for unconditional efforts.

Participants answered this question “How much effort do you think [participant’s country] should make to reduce climate change, if other countries do not make similar efforts?” on a 5-point scale (1 = no effort at all to 5 = a great deal of effort). There was an option of “Don’t know”; choosing this option was treated as a missing value. (UNCONDITIONAL; see Table 1 for descriptive statistics)

2.4.5. Covariates.

We treated the following four demographic variables as covariates: age (from 1 = 18–24–6 = 65 and over), gender (0 = female, 1 = male), income (different scales were used in different countries; see S2 for details), and education (1 = less than high school to 5 = Master’s degree or higher). Regarding climate change opinions (see Table 1 for the descriptive statistics), the questions included: “With respect to climate change, which of the following do you personally believe?” (0 = Climate change is NOT happening now/Climate change is happening now, but caused mainly by natural forces, 1 = Climate change is happening now, caused mainly by human activities); “In general, how worried are you about climate change?” (1 = not at all worried to 5 extremely worried); “How much do you think climate change will harm you personally?” (1 = not at all to 5 = a great deal); and “How much do you think climate change will harm people in [participant’s country]?” (1 = not at all to 5 = a great deal). Participants also reported their perceived scientific consensus of climate change by responding to this question: “As far as you know, what percentage of climate scientists think human activities are causing the world’s climate to change?” Participants indicated a percentage using a slider bar, with a “Don’t know” option. We observed that in the U.S. and Japan, 14.5% and 14.1% of the participants chose the “Don’t know” option. Including this variable in our subsequent analyses would substantially reduce our effective sample sizes, compromising our samples’ representativeness and analyses’ statistical power. We therefore decided to exclude this covariate from the analyses. Interested readers may refer to Table D in S1 Text for the results of another set of analysis wherein this covariate was included. The key results were consistent across the two sets of analysis.

Intercorrelations among the key variables (LIKELY, WILLING, EFFORT, OBLIGATION, UNCONDITIONAL) and climate change opinions are displayed in Table E in S1 Text.

As mentioned, our data came from a survey study on human responses to climate change [62]. At the very beginning, participants reported their demographic information, including gender, age, and income. After that, the questions were organized into 10 pages. All participants completed Page 1 first, which included questions about climate change opinions. Next, participants completed Page 2 to Page 7, which included other questions related to climate change. The order of these pages was randomized across participants, and the order of questions within each of these pages was randomized across participants. Questions related to the present study were on Page 3 (SUPPORT), Page 4 (LIKELY, WILLING and EFFORT), Page 5 (UNCONDITIONAL), and Page 6 (OBLIGATION). After completing these pages, participants proceeded to complete Pages 8–10, which contained questions unrelated to the present study and other questions regarding participants’ backgrounds, including education.

3. Results

3.1. Perception of climate efforts by other countries

We first explored how participants perceived other countries’ climate efforts. Fig 1 shows the response distributions.

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Fig 1. Distribution of responses of LIKELY, WILLING, and EFFORT in each country.

https://doi.org/10.1371/journal.pclm.0000755.g001

Regarding LIKELY, the full sample mean was slightly above the scale mid-point. 38.54% of the participants reported “very likely” or “extremely likely,” as opposed to 22.43% for “not at all likely” or “not very likely.” Similarly, for WILLING, the full sample mean was above the scale mid-point. 54.58% of the participants reported “somewhat agree” or “strongly agree,” as opposed to 21.10% for “somewhat disagree” or “strongly disagree.” In sum, the average perception based on all participants, regardless of country, can be said to be on the positive or optimistic side. Because the actual items for EFFORT varied between the four countries, we did not examine the full-sample results.

There were some noticeable differences between the four country samples. Specifically, there seemed to be more positive or optimistic perceptions among Chinese and Indian participants. Counting the Japanese and American samples alone, the average view was either around the mid-point or significantly below the mid-point. On the contrary, in the Chinese and Indian samples, the average view was almost always significantly above the mid-point. This pattern was consistently observed in LIKELY, WILLING, and EFFORT. These cross-national differences are potentially interesting and require future attention.

It is notable that LIKELY, WILLING, and EFFORT were moderately to strongly correlated with each other (see Table 2). That is, participants who perceived higher likelihoods of climate action by other countries also tended to report the perceptions that other countries were willing to contribute and that top emitters in the world were trying to reduce climate change. This observation suggests that the three measures converge to the same construct.

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Table 2. Correlational observations.

https://doi.org/10.1371/journal.pclm.0000755.t002

3.2. Effect of perception of climate efforts by other countries

Next, we tested Hypothesis 1. We first examined the zero-order correlations between the measures of perceived other countries’ climate efforts and support for climate policies (see Table 2). A significant (small to moderate) correlation was observed, regardless of the specific measure. It is noteworthy that the correlations were noticeably weaker in the Indian sample than the other three samples. Fig 2 visualizes the relationship between LIKELY and SUPPORT in each country as an illustration.

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Fig 2. Visualization of the relationship between LIKELY and SUPPORT.

https://doi.org/10.1371/journal.pclm.0000755.g002

We proceeded to test the hypothesis with a series of linear regression models with SUPPORT as the outcome variable. In each model, all covariates were included. In addition, either LIKELY, WILLING, or EFFORT was included as the key predictor. Tables 3–5 show the results. There was no consistent pattern regarding the demographic covariates. Some of the climate change opinion variables were significant predictors in some of the models; climate change worry and perceived harm of climate change to the country appeared to be the most robust ones. Most important, LIKELY, WILLING, or EFFORT was always a significant predictor in China, Japan, and the U.S. In India, WILLING was a significant predictor, whereas LIKELY and EFFORT were not.

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Table 3. Results regarding Hypothesis 1 (with LIKELY as predictor).

https://doi.org/10.1371/journal.pclm.0000755.t003

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Table 4. Results regarding Hypothesis 1 (with WILLING as predictor).

https://doi.org/10.1371/journal.pclm.0000755.t004

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Table 5. Results regarding Hypothesis 1 (with EFFORT as predictor).

https://doi.org/10.1371/journal.pclm.0000755.t005

There is some supportive evidence for Hypothesis 1. Participants who perceived stronger climate efforts by other consistently reported stronger support for climate policies. This held true even when a range of demographic variables and climate change opinions were controlled for. Notably, this association appeared to be less robust in our Indian sample. Examinations of the standardized coefficients provide a hint of the magnitude of this association. Generally speaking, the size of the significant associations between perceived efforts by other countries and policy support was at least comparable to that regarding other climate change opinions. In China, the standardized coefficients ranged from .135 to .187; the magnitude of these coefficients was comparable to that of climate change worry and always higher than that of the other climate change opinions. In India, the standardized coefficient for WILLING was .074, higher than that of climate change belief, but lower than that of the other climate change opinions. In Japan, the standardized coefficients ranged from .140 to .194; this magnitude was comparable to that of climate change belief, higher than that of climate change risk perception, but lower than that of climate change worry. In the U.S., the standardized coefficients ranged from .087 to .114; this magnitude was higher than that of risk perception regarding oneself, but lower than that of the other climate change opinions. In summary, these findings suggest that when it comes to predicting climate policy support, the role of perceptions of other countries’ efforts was at least as important as the commonly considered climate change opinions.

3.3. Interindividual variations

Next, we proceeded to test Hypothesis 2a with a series of regression models in which we added OBLIGATION and its interaction with either LIKELY, WILLING, or EFFORT. Table 6 shows the results. The interaction term was negative in 11 out of the 12 models, and it reached statistical significance in five of them (one in India, one in Japan, and all three in the U.S.). Notably, in China, the interaction term was not significant in all models. We performed a series of simple slope analysis to explicate the significant interaction effects. The simple slope of perceived other countries’ climate efforts was always stronger and mostly significant when OBLIGATION was low (1 SD below mean) but weaker and always non-significant when OBLIGATION was high (1 SD above mean). This pattern is consistent with Hypothesis 2a.

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Table 6. Results regarding Hypothesis 2a.

https://doi.org/10.1371/journal.pclm.0000755.t006

We then tested Hypothesis 2b with a series of regression models in which we added UNCONDITIONAL and its interaction with either LIKELY, WILLING, or EFFORT. Table 7 shows the results. The interaction term was negative in 11 out of the 12 models, and it reached statistical significance in six of them (two in China, two in India, and all three in the U.S.). Notably, in Japan, the interaction term was not significant in all models. The follow-up simple slope analyses revealed that the simple slope of perceived other countries’ climate efforts was always stronger and significant when UNCONDITIONAL was low (1 SD below mean) but weaker and mostly non-significant when UNCONDITIONAL was high (1 SD above mean). This pattern is consistent with Hypothesis 2b.

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Table 7. Results regarding Hypothesis 2b.

https://doi.org/10.1371/journal.pclm.0000755.t007

These analyses together suggest that there were some individual differences in terms of the association between perception of other countries’ efforts and support for climate policies. For participants who felt responsible for the happening of climate change and obligated to reduce it, and for participants who identified with unconditional efforts by their own country, they showed stronger support for climate policies and did not base such support as much on their perception of other countries’ efforts. However, it should also be noted that robust evidence regarding these interindividual variations was observed mainly in the U.S. In China, significant variations were found regarding WILLING or EFFORT and UNCONDITIONAL only. In India, significant variations were observed for LIKELY and OBLIGATION, and for WILLING and UNCONDITIONAL only. In Japan, significant variations were observed for WILLING and OBLIGATION only.

4. General discussion

4.1. Theoretical contributions

Is public support for climate policies contingent on what other countries do? Based on our findings, support appears to be conditional. Some previous studies have shown that most individuals, when explicitly asked, support unconditional efforts by their countries [33,32]. However, other studies have suggested that people in fact respond to other countries’ actions and efforts (e.g., [37, 34]). Our results speak to this debate. On average, we found that participants’ support for climate policies was associated with their perception of contributions by other countries, a pattern supporting our “They Reduce, We Reduce” hypothesis. However, interindividual variations of this contingency were observed. It appears that for some individuals (those who feel obligated to reduce climate change, or who explicitly support unconditional efforts by their country), climate policies are considered to be imperative, regardless of whether other countries are ambitious or lacklustre. Other individuals (those who do not feel obligated to reduce climate change, who support conditional efforts by their country) do not necessarily reject climate policies; some of them express support for these policies, provided that other countries are likely or willing to reciprocate their efforts or are already making such efforts.

We have contributed a novel perspective on what might constitute people’s positive evaluation of climate policies. Previous research has identified three main factors behind policy support: policy attributes, psychological orientations, and social contexts [16,9]. Our study suggests that perceptions of other countries’ actions and cooperativeness may also play a significant role.

One major line of research in the literature on climate opinions has focused on the assessment of people’s beliefs regarding the reality of climate change, and its causes, risk, scientific understanding, and impacts [67]. How citizens perceive other countries’ levels of commitment has, however, been rarely explored. We directly measured this perception and demonstrated its significance. Specifically, we employed three different but interrelated measures and found substantial individual differences. Notably, there were remarkable cross-national differences too. The perception by the Chinese and Indian participants appeared to be more positive in general. Counting the Japanese and American samples alone, the average view was either around the scale mid-point or significantly below the mid-point. On the contrary, in the Chinese and Indian samples, the average view was almost always significantly on the positive side against the scale mid-point.

In line with Hypothesis 2b, it was observed that for participants who explicitly identified with unconditional efforts by their own country, their attitudes toward domestic efforts were less contingent support on their perception of other countries’ efforts. While this observation may initially seem tautological, we believe it is important to note. Although it has been documented in previous studies (e.g., [33]) that some individuals explicitly support the view that their country’s climate action should be unconditional, it still remains unexplored as to how these individuals perceive the levels of efforts exerted by other countries and, most important, whether their attitudes toward domestic policies are really not influenced by such perceptions at all. On this note, the results of our simple slope analyses (Table 7) reveal some nuances that are worth considering. For instance, the association between perceived efforts by other countries and policy support was still significant in some cases for individuals reporting a moderate level of UNCONDITIONAL (that is, at sample mean level, which was above the scale mid-point in all four countries; see Table 1). In addition, the interaction between UNCONDITIONAL and LIKELY, WILLING, or EFFORT was not always significant. These results suggest that even individuals who express moderate to high support for unconditional climate efforts in their own country may still be influenced by their perceptions of other countries’ climate actions. In other words, while many people openly endorse unconditional climate efforts from their own nation (e.g., [33]), it is still possible that they consider the climate efforts of other countries when forming their opinions about domestic policies.

4.2. Practical implications

To slow down climate change, state and local governments all over the world must now aggressively ramp up their implementation of climate policies. It is difficult to imagine how these policies can be implemented without strong support from the public. Extrapolating from our “They Reduce, We Reduce” hypothesis, we put forward that the role of reciprocity in mobilizing public support should be considered. Specifically, highlighting the high levels of current or committed efforts by other countries in reducing emissions could be an effective tool in policy communication messages. This suggested tool has its theoretical underpinnings in evidence of the importance of reciprocity in solving collective action problems [38] and the power of social norms in behavioral and social change [68,69]. That said, this suggestion remains speculative and requires more large-scale and causal evidence. Also, as hinted by our findings, the effectiveness of this suggested tool is unlikely to be uniform and may apply to certain segments of the public or certain countries only.

4.3. Limitations and future research directions

To enhance the rigor of our study, we collected data from multiple countries and employed multiple measures of our key variable for robustness check of our results. However, the research still has the following limitations that need to be addressed in the future.

The study design was purely cross-sectional, limiting our ability to draw causal inference with confidence. Also, the possibility that policy support and perceived efforts by other countries reciprocally influence each other should not be overlooked. Specifically, it is plausible that individuals may possess a more optimistic view of other countries’ climate actions because they themselves support such actions. As studies on second-order beliefs have suggested, individuals may commit an egocentric bias, believing that other people share similar beliefs or actions as their own [28]. To address these issues, future studies with more rigorous designs, such as experiments or longitudinal studies, are needed. As an illustration, a recent experiment [70] demonstrated that presenting factual information about other countries’ implementation of a climate policy can increase people’s perception of other countries’ efforts, which, in turn, enhance their support for a similar policy in their country.

Our findings reveal some cross-national differences. The present research fails to test any formal explanation for these differences at the moment. We offer some speculations for testing in future studies. First, we found that Chinese and Indian participants on average displayed more optimistic perception regarding other countries’ climate efforts. This observation may reflect cross-cultural differences in optimism and life orientation [71,72]. It may also reflect substantively how different populations in this world understand the dynamics of global climate governance and how they evaluate other actors in the climate agenda. Second, there was a weaker association between perception of climate efforts by other countries and policy support in our Indian sample. It is attributable to that our Indian participants had generally high levels of moral obligation to reduce climate change and support for unconditional efforts by their country (see Table 1 for the statistics). When we explicitly took individual differences into account, even among Indian participants, we found that perception of other countries’ climate effort had a significant effect when moral obligation or support for unconditional climate efforts was low. Third, our evidence regarding interindividual variations was not robust in China and Japan. The effect of support for unconditional efforts but not moral obligation was observed in China, whereas the reverse was true Japan. This pattern is difficult to explicate, but we speculate that it might be due to the fact that there were less variations among our Asian samples than the U.S. sample for moral obligation or support for unconditional climate efforts to begin with (see Table 1 for the statistics).

It is unclear whether the public reacts differently to the climate efforts of different countries. Is it possible that their opinions on domestic climate policies are more influenced by the efforts of certain countries than those of others? Research on policy diffusion has demonstrated that countries are more likely to adopt climate policies when they share a similar structural position with countries that are actively engaged in the climate agenda (e.g., [25]), suggesting that the relational process driving policy diffusion may be selective. Additionally, given the existing geopolitical tension between certain countries, it is reasonable to expect that people may selectively respond to the climate efforts of other nations. These nuances can only be addressed in future studies that take the relationships between countries into account. As an exploration on this matter, we conducted an additional set of analysis. For each country, we conducted a regression model with perceived efforts by each country or region (excluding the participant’s own) individually included as predictors (see Table F in S1 Text for the results). In the U.S. sample, perceived efforts by China were the only positive significant predictor. In the Japan sample, perceived efforts by China and by the EU were both significant. For Indian participants, perceived efforts by Japan and the EU were both significant. In the Chinese sample, only perceived efforts by India were significant. These results are preliminary, and we reckon that more rigorous tests are needed in future research. Such research may need to consider the roles of individuals’ identification with their own country and their approval of the other specific countries/regions.

In the present study, we aimed to investigate whether the perception of other countries’ climate efforts—which was not conceptualized in a policy-specific manner—would affect individuals’ support for climate policy actions in general in their own countries. In developing the three measures for the perception of climate efforts by other countries, we referred to these efforts in a generic sense, without specifying any policies. Correspondingly, we created an aggregated index of support for climate policy actions in one’s own country based on multiple policies, which was justified based on an elaborate psychometric evaluation (see S3). This study design does not permit us to test a related hypothesis suggested by an anonymous reviewer: individuals’ perceptions of the prevalence of a specific policy (such as carbon taxation) in other countries may influence their support for the implementation of that same policy within their own country. To explore this intriguing possibility, a new future study incorporating policy-specific measures—namely, the perception of the prevalence or diffusion of a specific climate policy and support for that specific policy—is warranted. In such a study, other known policy-specific factors, such as perceived effectiveness and perceived fairness, should also be included as covariates.

5. Conclusion

Considering how citizens may respond to other countries’ actions, the present research situates the study of climate policy attitudes in the context of global climate governance. Using direct measures of respondents’ perceptions of other countries’ efforts, we were able to assess how optimistic or pessimistic individuals are when thinking about other countries’ commitment to slowing down climate change. Furthermore, by asking participants their attitudes towards a wide array of policies, we were able to establish the association between perceptions of other countries’ efforts and support for domestic efforts. Our findings support the “They Reduce, We Reduce” hypothesis. That is, on average, people’s climate policy support is related to their perceptions of other countries’ actions. There is also some evidence, albeit not universal, of variations across individuals. For individuals who do not feel obligated to contribute to climate change action, and who reject unconditional efforts by their country, there is a stronger association between their perceptions of other countries’ climate efforts and support for domestic policies.

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